Fiche individuelle
Frédéric COLAS  
Titre  Ingénieur de recherche  
Equipe  Réseaux  
Téléphone  +33 (0)320622949  
Fax  +33 (0)320622750  
frederic.colas@ensam.eu  
Observation / Thématique de recherche  Simulation temps réel et contrôle des réseaux électriques  
Publications 
ACLI Revue internationale avec comité de lecture 

[1] Current Limiting Algorithms and Transient Stability Analysis of GridForming VSCs Electric Power Systems Research (EPSR), 08/2020 QORIA Taoufik, GRUSON François, COLAS Frédéric, GUILLAUD Xavier, KESTELYN Xavier 
[2] A Novel Event and NonProjectionBased Approximation Technique by State Residualization for the Model Order Reduction of Power Systems with a High Renewable Energies Penetration IEEE Transactions on Power Systems, 07/2020, Abstract COSSART Quentin, COLAS Frédéric, KESTELYN Xavier 
The fast development of renewable energies leads to an increase in the power electronics penetration in transmission systems. This is particularly true if one considers a 100% renewable energies power system, where wind and solar photovoltaic energies, which make most of the renewable energies connections today, are connected to the grid through power electronics converters. Because power electronicsbased generators and synchronous machinesbased generators have very different dynamic behaviours, some approximations usually used to run transient simulations of transmission systems might not be optimal for future grids. The systematic use of the phasor approximation applied to the power lines, implemented in most of the Transient Simulation Programs, is indeed not relevant any more. To avoid the use of Electromagnetic Transient simulations, that are resourcedemanding and timeconsuming, this paper presents a novel Model Order Reduction technique for large grids with a high penetration of power electronic devices. Compared to the classical phasor approximation, this eventbased state residualization approximation allows accurate transient simulations and at the same time an optimal reduction of the number of the system's state variables depending on the observed variables, the considered events and the tolerated approximation error. 
[3] Nonlinear primary control mapping for drooplike behavior of microgrid systems IEEE Transactions on smart grid, 06/2020 LEGRY Martin, DIEULOT JeanYves, COLAS Frédéric, SAUDEMONT Christophe, DUCARME Olivier 
[4] DQ impedance stability analysis for the powercontrolled gridconnected inverter IEEE Transactions on Energy Conversion, 05/2020 LI Chuanyue Li, JUN Liang, CIPCIGAN Liana, WENLONG Ming, COLAS Frédéric, GUILLAUD Xavier 
[5] A Novel DC Fault Ride Through Control Methodology for Hybrid Modular Multilevel Converters in HVDC Systems IEEE Transactions on Power Delivery, 05/2020, Abstract SHAHRIARI Ejlal, GRUSON François, VERMEERSCH Pierre, DELARUE Philippe, COLAS Frédéric, GUILLAUD Xavier 
Modular Multilevel Converter (MMC) is an established technology for HVDC or MultiTerminal DC (MTDC) systems, due to its advantages over classical Voltage Source Converters (VSCs) such as two or three level VSCs. To achieve a full control of all state variables, it is essential to implement energybased method in which a cascade control loop is employed to regulate all state variables including ac and differential currents, and stored energy within MMC arms. In addition to normal operation control, dc Fault Ride Through (DCFRT) capability of the MMC is a crucial and challenging control issue especially for overhead line HVDC system where nonpermanent dc fault occurrence is statistically more probable. Furthermore, the main problematic technical obstacle to develop HVDC/MTDC grids is the lack of mature dc fault protection. Since conventional control in normal operation cannot be employed in case of dc fault, an efficient control strategy is indispensable. The principal objectives of the novel control methodology are to (i) obtain DCFRT capability, (ii) decay short circuit current to zero, (iii) secure the MMC through leg and arm energy balancing, (iv) support ac grid as a Static Synchronous Compensator (STATCOM) and (v) resume normal operation after dc fault clearance. The simulation results verify the validity of proposed control strategy to fulfill the abovementioned objectives in dc fault operation of the hybrid MMC. 
[6] On Comprehensive Description and Analysis of MMC Control Design: Simulation and Experimental Study IEEE Transactions on Power Delivery, 03/2020, URL, Abstract ZHANG Haibo, BELHAOUANE Moez, COLAS Frédéric, KADRI Riad, GRUSON François, GUILLAUD Xavier 
This paper presents an evolution of control systems of Modular Multilevel Converters (MMCs) focusing on the internal voltages and currents dynamics. MMCs have passive components that create extra dynamics compared to conventional VSCs. Some control schemes that do not consider these internal dynamics may still stabilize the system asymptotically thanks to the linearisation in the modulation step. However these control schemes are less robust because they are prone to poor damped oscillations on the dc side of the converter. The MMC circuit and energy relationships are presented in this paper. Along with a gradual development of the energy based control, the important roles of each internal dynamics are clearly demonstrated. Experimental results are presented to show the impacts of the linearisation in the modulation step on the system behaviour. 
[7] Convex formulation of confidence level optimization of DG affine reactive power controllers in distribution grids Electric Power Systems Research, Vol. 180, pages. 106132, 03/2020, URL, Abstract BUIRE Jérôme, DIEULOT JeanYves, COLAS Frédéric, GUILLAUD Xavier, DE ALVARO GARCIA Léticia 
Volatile productions and consumptions generate a stochastic behavior of distribution grids and make its supervision difficult to achieve. Usually, the Distributed Generators reactive powers are adjusted to perform decentralized voltage control. Industrial controllers are generally equipped with a local affine feedback law, which settings are tuned at early stage using local data. A centralized and more efficient tuning method should aim to maximize the probability that all the node voltages of distribution grids remain within prescribed bounds. When the characteristics of the stochastic power forecasts are known, the centralized algorithm allows to update the settings on a regular time basis. However, the method requires to solve stochastic optimization problem. Assuming that stochastic variables have Gaussian distributions, a procedure is given which guarantees the convergence of the stochastic optimization. Convex problems drastically reduce the difficulty and the computational time required to reach the global minimum, compared to nonconvex optimal power flow problems. The linear controllers with optimized parameters are compared to traditional control laws using simulations of a real distribution grid model. The results show that the algorithm is reliable and moreover fast enough. Hence, the proposed method can be used to update periodically the control parameters. 
[8] Direct AC Voltage Control for Gridforming Inverters Journal of Power Electronics, 12/2019, URL, Abstract QORIA Taoufik, LI Chuanyue Li, OUE Ko, GRUSON François, COLAS Frédéric, GUILLAUD Xavier 
Gridforming inverters usually use inner cascaded controllers in order to regulate the output AC voltage and the converter
output current. Yet, at the power transmission system level where the power inverter bandwidth is limited (i.e.; low switching
frequency), it is difficult to tune its controller parameters to achieve the desired performances because of the control loops
interactions. In this paper, a direct AC voltage control based statefeedback control is applied. Its control gains are tuned using
the linear quadratic regulator. In this paper, a sensitivity analysis is proposed in order to choose the right cost factors that allow
the system to achieve the imposed specifications. Conventionally, the system based on direct AC voltage control has no restriction on the inverter current. Hence, in this paper, threshold virtual impedance has been added to the statefeedback control in order to protect the inverter against overcurrent. The robustness of the proposed control is assessed for different short circuit ratio using small signal stability analysis, then, checked in different grid topologies using time domain simulations. An experimental test bench is developed in order to validate the proposed control. 
[9] Critical clearing time determination and enhancement of gridforming converters embedding virtual impedance as current limitation algorithm IEEE Journal of Emerging and Selected Topics in Power Electronics, 12/2019, URL, Abstract QORIA Taoufik, GRUSON François, COLAS Frédéric, DENIS Guillaume, PREVOST Thibault, GUILLAUD Xavier 
The present paper deals with the postfault synchronization of a voltage source converter based on the droop control. In case of large disturbances on the grid, the current is limited via current limitation algorithms such as the virtual impedance. During the fault, the power converter internal frequency deviates resulting in a converter angle divergence. Thereby, the system may lose the synchronism after fault clearing and which may lead to instability. Hence, this paper proposes a theoretical approach to explain the dynamic behavior of the grid forming converter subject to a three phase bolted fault. A literal expression of the critical clearing time is defined. Due to the precise analysis of the phenomenon, a simple algorithm can be derived to enhance the transient stability. It is based on adaptive gain included in the droop control. These objectives have been achieved with no external information and without switching from one control to the other. To prove the effectiveness of the developed control, experimental test cases have been performed in different faulted conditions. 
[10] Stochastic Optimization of PQ Powers at the Interface between Distribution and Transmission Grids Energies, Vol. 12, N°. 21, 10/2019, URL, Abstract BUIRE Jérôme, COLAS Frédéric, DIEULOT JeanYves, GUILLAUD Xavier 
This paper addresses the voltvar control of distribution grids embedding many distributed generators (DGs). Specifically, it focuses on the compliance of powers to specified PQ diagrams at the high voltage/medium voltage (HV/MV) interface while the voltages remain well controlled. This is achieved using a twostage optimization corresponding to two different classes of actuators. The tap position of capacitor banks is selected on a daily basis, given a stochastic model of the input powers prediction, which allows infrequent actuation and increases the device lifespan. In a second stage, a confidence level optimization problem allows to tune on an hourly basis the parameters of the DGs reactive power affine control laws. Results on a realsize grid show that the combined tuning of these actuators allows the ability to comply with European grid codes while the control effort remains reasonable. 
[11] Coupling influence on the dq impedance stability analysis for the threephase gridconnected inverter MDPI Energies, 09/2019, URL, Abstract LI Chuanyue Li, QORIA Taoufik, COLAS Frédéric, JUN Liang, WENLONG Ming, GRUSON François, GUILLAUD Xavier 
The dq impedance stability analysis for a gridconnected currentcontrol inverter is based
on the impedance ratio matrix. However, the coupled matrix brings the difficulties to derive its
eigenvalues for the analysis based on the General Nyquist Criterion. If the couplings are ignored for
simplification, the unacceptable errors will present in the analysis. In this paper, the influence of the
couplings on the dq impedance stability analysis is studied. For taking the couplings into account
simply, the determinantbased impedance stability analysis is used. The mechanism between the
determinant of the impedanceratio matrix and the inverter stability is unveiled. Compared to the
eigenvaluesbased analysis, only one determinant rather than two eigenvalue sfunction is required
for the stability analysis. One Nyquist plot or polemap can be applied to the determinant for checking
the righthalfplane poles. The accuracy of the determinantbased stability analysis is also checked
by comparing with the statespace stability analysis method. For the stability analysis, the coupling
influence on the current control, phaselocked loop and the grid impedance are studied. The errors
can be 10% in the stability analysis if the couplings are ignored. 
[12] Full State Regulation of the Modular Multilevel DC converter (M2DC) achieving minimization of circulating currents IEEE Transactions on Power Delivery, Vol. 35, pages. 301309, 09/2019, URL, Abstract GRUSON François, LI Yafang, DELARUE Philippe, LE MOIGNE Philippe, COLAS Frédéric, GUILLAUD Xavier 
The M2DC exploits the interleaving between the three legs of an MMC to realize a promising uninsulated DC/DC converter to interconnect HVDC grids. This paper details a current and energies decoupled model of the M2DC. The major idea proposed in this paper is focused on the full energy control generating optimal current references to minimize the internal currents magnitude. The energy sum and difference models are fully detailled. Both current and energy control loops are based on the model inversion principle in order to control all the state variables. The proposed control is based a dynamic control developed with the model inversion principle associated on an optimization of the current magnitude deduced from a quasi static analysis. All dynamics of the system are then explicitly controlled, which guarantee a good dynamic behavior during the transient. Therefore, current and energy controls are presented in details. Simulation results show the dynamic behavior of the converter for various operating points. 
[13] Confidence level optimization of DG piecewise affine controllers in distribution grids IEEE Transactions on Smart Grid, 02/2019, URL, Abstract BUIRE Jérôme, COLAS Frédéric, DIEULOT JeanYves, DE ALVARO GARCIA Léticia, GUILLAUD Xavier 
Distributed generators (DG) reactive powers are controlled to mitigate voltage overshoots in distribution grids with stochastic power production and consumption. Classical DGs controllers may embed piecewise affine laws with deadband terms. Their settings are usually tuned using a decentralized method which uses local data and optimizes only the DG node behavior. It is shown that when shortterm forecasts of stochastic powers are Gaussian and the grid model is assumed to be linear, nodes voltages can either be approximated by Gaussian or sums of truncated Gaussian variables. In the latter case, the voltages probability density functions (pdf) that are needed to compute the overvoltage risks or DG control effort are less straightforward than for normal distributions. These pdf are used into a centralized optimization problem which tunes all DGs control parameters. The objectives consist in maximizing the confidence levels for which voltages and powers remain in prescribed domains and minimizing voltage variances and DG efforts. Simulations on a real distribution grid model show that the truncated Gaussian representation is relevant and that control parameters can easily be updated even when extra DGs are added to the grid. The DG reactive power can be reduced down to 50 % or node voltages variances can be reduced down to 30 %. 
[14] Dynamic Analysis of MMCBased MTDC Grids: Use of MMC Energy to Improve Voltage Behavior IEEE Transactions on Power Delivery, 09/2018, URL, Abstract FREYTES Julian, AKKARI Samy, RAULT Pierre, BELHAOUANE Moez, GRUSON François, COLAS Frédéric, GUILLAUD Xavier 
This article deals with DC voltage dynamics of MultiTerminal HVDC grids with energybased controlled Mo\dular Multilevel Converters (MMC) adopting the commonly used powervoltage droop control technique for power flow dispatch. Special focus is given on the energy management strategies of the MMCs and their ability to influence on the DC voltage dynamics. First, it is shown that decoupling the MMC energy from the DC side by controlling the energy to a fixed value, regardless of the DC voltage level, causes large and undesired DC voltage transient after a sudden power flow change. Second, the Virtual Capacitor Control technique is implemented in order to improve the results, however, its limitations on droopbased MTDC grids are highlighted. Finally, a novel energy management approach is proposed to improve the performance of the later method. These studies are performed with detailed MMC models suitable for the use of linear analysis techniques. The derived MTDC models are validated against timedomain simulations using detailed EMT MMC models with 400 submodules per arm. 
[15] Coordinated control of active distribution networks to help a transmission system in emergency situation Energy Systems, 04/2018, URL, Abstract MORIN Juliette, COLAS Frédéric, DIEULOT JeanYves, GRENARD Sébastien, GUILLAUD Xavier 
This paper addresses the relevance of using reactive power from Medium Voltage (MV) networks to support the voltages of a High Voltage (HV) rural network in realtime. The selection and analysis of different optimal coordination strategies between the HV and several MV grids is investigated. The algorithms will control the reactive powers that can flow between HV/MV networks after a request from the Transmission Network Operator in case of an emergency situation such as a line outage. From a case study, the relevance of the coordination is enlightened and recommendations are given on how to tune and to combine the optimal algorithms with the advanced Volt Var Controllers of the distribution grids. 
[16] Design, implementation and testing of a Modular Multilevel Converter EPE Journal, Vol. 27, N°. 4, 12/2017, Abstract GRUSON François, KADRI Riad, COLAS Frédéric, GUILLAUD Xavier, DELARUE Philippe, BERGÉ Marta, DENNETIERE Sébastien, OULD BACHIR Tarek 
The Modular Multilevel Converter (MMC) is a power electronic structure used for high voltage adjustable speed drives applications as well as power transmission applications and highvoltage direct current (HVDC). MMC structure presents many advantages such as modularity, the absence of a high voltage DC bus and very low switching frequency. It presents also some disadvantages such as modeling complexity and control due to the large number of semiconductors to control. The objectives of this paper are to present the methodology to design a laboratory MMC converter and its control system. This methodology is based on an intensive used of realtime simulation, to develop and test the control algorithm is proposed. This MMC prototype must be as realistic as possible to a full scale MMC, with a large number of SM (i.e. 640kV on the DC side, a rated power of 1GW and 400 submodules). A control hardware integrating distributed processors (one for each arm) and a master control is presented. The protocols to validate submodules, arms and the converter are explained. 
[17] Improving SmallSignal Stability of an MMC with CCSC by Control of the Internally Stored Energy IEEE Transactions on Power Delivery, 11/2017 FREYTES Julian, GILBERT Bergna, JON ARE Suul, SALVATORE D'Arco, GRUSON François, COLAS Frédéric, SAAD Hani, GUILLAUD Xavier 
[18] Laboratory Demonstration of a MultiTerminal VSCHVDC Power Grid IEEE Transactions on Power Delivery, Vol. PP, N°. 99, 11/2016, Abstract AMAMRA SidAli, COLAS Frédéric, GUILLAUD Xavier, RAULT Pierre, NGUEFEU Samuel 
This paper presents the design, development, control and supervision of a hardwarebased laboratory Multi TerminalDirectCurrent (MTDC) testbed. This work is a part of the TWENTIES (Transmission system operation with large penetration of Wind and other renewable Electricity sources in Networks by means of innovative Tools and Integrated Energy Solutions) DEMO 3 European project which aims to demonstrate the feasibility of a DC grid through experimental tests. This is a hardwareintheloop DC system testbed with simulated AC systems in real time simulation; the DC cables and some converters are actual, at laboratory scale. The laboratory scale testbed is homothetic to a full scale high voltage direct current (HVDC) system: electrical elements are the same in per unit. The testbed is supervised by a Supervisory Control And Data Acquisition (SCADA) system based on PcVue. Primary control based droop control method to provide DC grid power balance and coordinated control methods to dispatch power as scheduled by transmission system operator (TSO) are implemented. Since primary control acts as converter level by using local measurements, a coordinated control is proposed to manage the DC grid power flow. The implemented system is innovative and achievable for realtime, realworld MTDCHVDC grid applications. 
[19] Embedding OLTC nonlinearities in predictive Volt Var Control for active distribution networks Electric Power System Research, 10/2016 MORIN Juliette, COLAS Frédéric, DIEULOT JeanYves, GRENARD Sébastien, GUILLAUD Xavier 
[20] MMC Stored Energy Participation to the DC Bus Voltage Control in an HVDC Link IEEE Transactions on Power Delivery, Vol. 31, N°. 4, pages. 17101718, 08/2016, Abstract SAMIMI Shabab, GRUSON François, DELARUE Philippe, COLAS Frédéric, BELHAOUANE Moez, GUILLAUD Xavier 
The modular multilevel converter (MMC) is be coming a promising converter technology for HVDC transmission systems. Contrary to the conventional two or threelevel VSCHVDC links, no capacitors are connected directly on the dc bus in an MMCHVDC link. Therefore, in such an HVDC link, the dc bus voltage may be much more volatile than in a conventional VSCHVDC link. In this paper, a connection between the dc bus voltage level and the stored energy inside the MMC is proposed in order to greatly improve the dynamic behavior in case of transients. EMT simulation results illustrate this interesting property on an HVDC link study case. 
[21] Distributed Economic Dispatch of Embedded Generation in Smart Grids Engineering Applications of Artificial Intelligence, Vol. 44, pages. 6478, 10/2015 DIBANGOYE Jilles, DONIEC Arnaud, FAKHAM Hicham, COLAS Frédéric, GUILLAUD Xavier 
[22] Economic supervisory predictive control of a hybrid power generation plant Electric Power Systems Research, Vol. 127, pages. 221229, 10/2015, URL, Abstract DIEULOT JeanYves, COLAS Frédéric, CHALAL Lamine, DAUPHINTANGUY Geneviève 
This work deals with the development of an economic supervisory predictive control method for the management of a hybrid renewable energy system. The hybrid cell integrates solar panels, a gas microturbine and a storage unit. Tuning the predictive controller is easy: the optimal criterion encompasses the environmental, fuel, energy delivery and storage costs. Short time predictions of the solar power are embedded in the supervisor which yields smoother battery control and better power management. Realtime experiments are driven in a HardwareintheLoop framework illustrating the relevance of the proposed supervisory predictive control design. 
[23] Eventtriggered variable horizon Supervisory Predictive control of hybrid power plants Control Engineering Practice, Vol. 34, pages. 6167, 01/2015, URL, Abstract DIEULOT JeanYves, COLAS Frédéric, CHALAL Lamine, DAUPHINTANGUY Geneviève 
The supervision of a hybrid power plant, including solar panels, a gas microturbine and a storage unit operating under varying solar power profiles is considered. The Economic Supervisory Predictive controller assigns the power references to the controlled subsystems of the hybrid cell using a financial criterion. A prediction of the renewable sources power is embedded into the supervisor. Results deteriorate when the solar power is unsteady, owing to the inaccuracy of the predictions for a longrange horizon of 10 s. The receding horizon is switched between an upper and a lower value according to the amplitude of the solar power trend. Theoretical results show the relevance of horizon switching, according to a tradeoff between performance and prediction accuracy. Experimental results, obtained in a Hardware In the Loop (HIL) framework, show the relevance of the variable horizon approach. Power amplifiers allow us to simulate virtual components, such as a gas microturbine, and to blend their powers with that of real devices (storage unit, real solar panels). In this case, fuel savings, reaching 15%, obtained under unsteady operating conditions lead to a better overall performance of the hybrid cell. The overall savings obtained in the experiments amount to 12%. 
[24] Emission Reduction and Economical Optimization of an Microgrid Operation Including Dispatched PVBased Active Generators IEEE Transactions On Sustainable Energy, Vol. 5, N°. 4, pages. 1755  1796, 10/2014 KANCHEV Hristiyan, COLAS Frédéric, LAZAROV Vladimir, FRANCOIS Bruno 
[25] Fuzzy Logic based Energy Management Strategy for Commercial Buildings Integrating Photovoltaic and Storage Systems Energy and Buildings, Elsevier, Vol. 54, pages. 196206, 12/2012, Abstract ZHANG He, DAVIGNY Arnaud, COLAS Frédéric, POSTE Y, ROBYNS Benoît 
This paper presents an energy management strategy for a commercial building in supermarket application. Some
objectives are established as load shedding, to reduce the electricity bill and the CO2 emissions of commercial building,
using photovoltaic (PV) and storage systems. An energy management supervision strategy based on the rules of the
electricity bill will be presented. This paper focuses on the supervision strategy with the help of fuzzy logic and a
graphical methodology to build it. It is shown, with the help of simulations and some economic and ecological indicators
that the energy bill cost and the CO2 emissions can be reduced by using the proposed solution 
[26] Energy Management and Operational Planning of a Microgrid With a PVBased Active Generator for Smart Grid Applications IEEE Transactions on Industrial Electronics, Vol. 58, N°. 10, pages. 4583  4592, 10/2011, Abstract KANCHEV Hristiyan, LU Di, COLAS Frédéric, LAZAROV Vladimir, FRANCOIS Bruno 
The development of energy management tools for nextgeneration PhotoVoltaic (PV) installations, including storage units, provides flexibility to distribution system operators. In this paper, the aggregation and implementation of these determinist energy management methods for business customers in a microgrid power system are presented. This paper proposes a determinist energy management system for a microgrid, including advanced PV generators with embedded storage units and a gas microturbine. The system is organized according to different functions and is implemented in two parts: a central energy management of the microgrid and a local power management at the customer side. The power planning is designed according to the prediction for PV power production and the load forecasting. The central and local management systems exchange data and order through a communication network. According to received grid power references, additional functions are also designed to manage locally the power flows between the various sources. Application to the case of a hybrid supercapacitor batterybased PV active generator is presented.

[27] Bond Graph Based Control of a Three Phase Inverter with LC Filter – Connection to Passive and Active Loads Simulation Modeling Practices and Theory, Vol. 18, N°. 9, pages. 11851198, 10/2010 SANCHEZ Roberto, DAUPHINTANGUY Geneviève, GUILLAUD Xavier, COLAS Frédéric 
[28] Robust PID control of a linear mechanical axis: A case study Mechatronics, Elsevier, Vol. 19, N°. 2, pages. 269273, 03/2009 DIEULOT JeanYves, COLAS Frédéric 
[29] Composite Predictive Functional Control Strategies, Application to
Positioning Axes International Journal of Computers, Communications & Control, Vol. 1, pages. 4150, 01/2008 DIEULOT JeanYves, BENHAMMI Tarik, COLAS Frédéric, BARRE PierreJean 
[30] Numerical aspects and performances of trajectory planning methods of flexible axes IJCSNS International Journal of Computer Science and Network Security, Vol. I, N°. 4, pages. 3544, 11/2006, Abstract DIEULOT JeanYves, THIMOUMI Issam, COLAS Frédéric, BEAREE Richard 
Adequate Path Planning design is an important stage for controlling flexible axes because it may allow to cancel vibrations induced by oscillating modes. Among bangbang profiles which are linked to optimal control, jerk assignment (acceleration derivative) and input shapers have been investigated. Theoretical results show the performance and robustness with respect to natural frequency mismatch. Practical validations on a real robot arm show the relevance of the jerk algorithm which is more robust with the same productivity performances as input shaping techniques. 
[31] Control of an industrial robot using acceleration feedback Journal of Intelligent & Robotic Systems, Vol. 46, pages. 111128, 05/2006, URL, Abstract DUMETZ Eric, DIEULOT JeanYves, BARRE PierreJean, COLAS Frédéric, DELPLACE Thomas 
Abstract. A controller using acceleration feedback has been applied to a flexible cartesian robot for which the position and velocity of the load are not measured. It is shown that acceleration feedback allows an exact tracking of the motor position, irrespective of the nonlinear flexibilities of the axes and of the measurement disturbances. This easytotune algorithm which main control parameters are the modal masses of the motor and load part, and only consists of a positive acceleration feedback plus a PD controller, has been validated on an industrial pickandplace robot. 
[32] Dynamics modeling and Causal Ordering Graph representation of a non minimum phase flexible arm fixed on a cart Wseas Transactions on systems, Vol. 5, N°. 1, pages. 916, 01/2006, URL COLAS Frédéric, DIEULOT JeanYves, BARRE PierreJean, BORNE Pierre 
ACLN Revue nationale avec comité de lecture 
[1] Méthodologie de conception de la commande des axes linéaires flexibles – 2ème partie synthèse et commande Technologies et Formations, Vol. 136, pages. 2638, 04/2008, Abstract COLAS Frédéric, REMY Ghislain, BARRE PierreJean 
Cette deuxième partie généralise le concept d’inversion de modèle.Nous proposons une méthode systématique d’élaboration de la commande des processus électromécaniques à partir d’un modèle utilisant le concept d’énergies localisées et décrit par le formalisme du Graphe Informationnel Causal.Les limites d’utilisation de ces techniques sont évoquées en fonction de critères tels que :les performances en poursuite et en régulation,l’influence des bruits de mesure,les limites énergétiques, les performances en suivi de trajectoire, la réalité technologique. On montre que certaines solutions, classiques ou particulières, sont retrouvées formellement. L’intérêt est de montrer l’aspect déductif systématique de la démarche,visant à une recopie fidèle des trajectoires souhaitées.Ces principes d’inversion sont ensuite appliqués à la synthèse de commande d’un axe de robot cartésien pour en déduire une commande par retour accélérométrique qui permet de compenser directement l’effet d’un mode souple. 
[2] Influence de différentes structures de commande sur le
compromis temps/vibration – Application à une machine UGV AFM, EDP Sciences  Mécanique & Industries, Vol. 8, N°. 5, pages. 429436, 10/2007 COLAS Frédéric, DIEULOT JeanYves, BARRE PierreJean 
[3] Méthodologie de conception de la commande des axes linéaires flexibles 1ère partie : modélisation générique Technologies et Formations, Vol. 131, pages. 2235, 03/2007, Abstract COLAS Frédéric, DIEULOT JeanYves, BARRE PierreJean 
Le but de cet article est de proposer une méthodologie de conception générique de la commande des axes linéaires flexibles. Cette première partie s’intéresse plus précisément à la modélisation mécanique d’un robot cartésien utilisé principalement dans la décharge de presse à injection plastique. Dans un premier temps, le comportement de ce robot est analysé à partir de son modèle élémentsfinis pour obtenir ses principaux modes de déformation. Les résultats obtenus sont ensuite validés par analyse modale expérimentale. Un modèle mathématique entièrement continu du comportement d’un axe de ce robot est déduit de ces analyses. La discrétisation de ce modèle permet d’obtenir des modèles à paramètres localisés utilisés, dans la deuxième partie, pour la conception de stratégies de commande en appliquant les principes d’inversion sur leurs représentations par Graphe Informationnel Causal. 
ACT Conférence internationale avec acte 
[1] Analysis of the coupling between the outer and inner control loops of a Gridforming Voltage Source Converter EPE2020, 09/2020, Abstract QORIA Taoufik, GRUSON François, COLAS Frédéric, KESTELYN Xavier, GUILLAUD Xavier 
The question of grid forming control is very different depending on the connection to a low voltage or high voltage grid. In case of higher power application, the low switching frequency may induce some stability issues. This question has been studied and some solutions have been proposed through new inner current and voltage control tuning methods. However, the possible interactions between the inner and the outer controls have not been discussed yet. Actually, in large power system, the phasor modeling approximation is used in order to ease the analysis and reduce the time computations. It assumes a good decoupling between the control loops, which allows neglecting the inner loop dynamics. This paper investigates the effectiveness of this assumption by taking some examples of tuning methods proposed in the literature and showing the ability of each method to guarantee the decoupling between controllers. In this paper, smallsignal analysis tool, participation factors and parametric sensitivities are used. 
[2] Impact on the electrical characteristics, waveforms and losses of the zerosequence injection on the Modular Multilevel Converter EPE2020, 09/2020, Abstract GRUSON François, VERMEERSCH Pierre, DELARUE Philippe, LE MOIGNE Philippe, COLAS Frédéric, ZHANG Haibo, BELHAOUANE Moez, GUILLAUD Xavier 
The MMC is the solution today to connect HVDC grids to the current HVAC grid. This paper proposes to evaluate the impact of Zero Sequence Voltage Injection variants, which until now, have not been extensively studied. Such techniques can involve, for example, a reduction of the SM capacitor value, the number of SM requirement and converter losses. The paper presents MMC current model, control and highlights the implication of the zerosequence voltage. Grid current control structure with the introduction of the zerosequence voltage is presented in different techniques. These modulation schemes are compared through two main quantities in MMC, the energy requirement defining the SM capacitance value and the power losses. 
[3] Current Limiting Algorithms and Transient Stability Analysis of GridForming VSCs PSCC 2020, 06/2020 QORIA Taoufik, GRUSON François, COLAS Frédéric, GUILLAUD Xavier, KESTELYN Xavier 
[4] Development of a power hardware in the loop simulation of an islanded microgrid IECON'19, 10/2019, Abstract FAKHAM Hicham, QORIA Taoufik, LEGRY Martin, DUCARME Olivier, COLAS Frédéric 
In this paper a Power Hardware in the loop
simulation has been realized to test in a safely way the
performances and reliability of a device called “PowerCorner”
used to supply an islanded microgrid. A realtime model has
been developed in order to simulate the microgrid, batteries and
photovoltaic panels. Some modeling criterions have been
proposed to reduce timestep simulation and enhancing the
Power Hardware in the loop simulation stability. Power
Hardware in the loop simulation is used to emulate the AC and
DC environments around the power inverters. On the DC side,
DC power amplifier is used to emulate photovoltaic power
plants and storage devices made on Lithium batteries. On the
AC side, AC power amplifier is used to emulate the behavior of
the microgrid. These two power amplifiers are controlled by a
digital real time simulator which embeds the dynamic behavior
of both DC and AC sides. 
[5] Stochastic estimation of PQ powers at the interface between distribution and transport grids 2019 IEEE PES Innovative Smart Grid Technologies Europe (ISGTEurope), pages. 15, 10/2019, URL, Abstract BUIRE Jérôme, COLAS Frédéric, DIEULOT JeanYves, DE ALVARO GARCIA Léticia, GUILLAUD Xavier 
The insertion of stochastic renewable energies in distribution grids generates important voltage fluctuations and reactive power exchange between distribution grids and transmission grids. These variations need to comply with European grid codes. The control strategy involves the actuation of the On Load Tap Changer and Capacitor Banks tap position, and the reactive powers of the DGs. This paper focuses on the stochastic estimation of the powers at the interface and the influence of the Capacitor Bank tap position. The main results are that, using a simplified stochastic model of the grid, one can obtain the distribution of the powers, and select, on a daily basis, the tap position which minimizes the level of the prescribed PQ diagram violation risk. This study paves the way for a voltvar stochastic optimization of the distribution grid. 
[6] Power Converters Classification and Characterization in Power Transmission Systems EPE'19, 09/2019, Abstract QORIA Taoufik, PREVOST Thibault, DENIS Guillaume, GRUSON François, COLAS Frédéric, GUILLAUD Xavier 
Because of the throng of control strategies based Voltage Source Converters (VSC) recently proposed
in the literature; their classification and characterization are becoming a trending topic. The high
similarities of the proposed control strategies may lead to confusions and a misunderstanding of
vocabulary. Therefore, this paper seeks first to highlight the possible features fulfilled by power
converters in a large power system. The combination of these features is used to classify power
converters. Furthermore, power converters can be seen by a power transmission system operators as
black boxes, and they may have the same inputs and outputs, which makes their characterizations
more difficult. This paper looks to show that only the fundamental nature of the source has an
influence on the system dynamic behavior, thus, power converter can be characterized from their
transient behavior in response to grid disturbances. 
[7] Modeling and Analysis of Modular Multilevel Converters connected to Weak AC Grids EPE 2019 ECCE Europe, 09/2019, URL, Abstract BELHAOUANE Moez, FREYTES Julian, RAULT Pierre, COLAS Frédéric, GUILLAUD Xavier 
The Modular Multilevel Converter (MMC) represents the recent development among the diverse available topologies of VSC and is allegedly the most suitable solution for converters in HVDC transmission systems. This paper investigates the stability of modular multilevel converters based HVDC system connected to a weak ac grid. Small signal stability based on eigenvalues analysis is used to study the interaction between the weak ac grid and the converter. The impact of control parameters, mainly the synchronization system (i.e., Phase Locked Loop) on the stability of the MMC is also considered in frequency domain. Finally, timedomain simulations and frequency domain analysis are carried out using MATLAB/Simulink and symbolic toolbox to validate the effectiveness of the proposed study. 
[8] A RealTime HIL Test Bench for Modular Multilevel Converter with Energy Based Control The 13th IEEE PowerTech2019 Conference, 06/2019, URL, Abstract ZHANG Haibo, BELHAOUANE Moez, COLAS Frédéric, KADRI Riad, GRUSON François, GUILLAUD Xavier 
The modular multilevel converter (MMC) is recognized for many advantages over conventional 2level or 3level voltage source converters (VSC). One of the features is that it is possible to control the stored energy in the distributed
submodule (SM) capacitors. The aim of this paper is to propose a methodology to develop the control system implemented on a 21level MMC mockup. This control must be ﬁrst validated in a realtime (RT) simulation environment with an accurate MMC model representing the behaviour of the physical MMC mockup. Then it is performed in the hardwareintheloop (HIL) simulation before the implementation. The power system is emulated in a real time simulator from OpalRT Technologies, which is connected to an external control system programmed in a dualcore microcontroller. The developed HIL platform facilitates the tests of the control and protection system in all possible scenarios. 
[9] Electromagnetic Transients (EMT) Model Design based on Modular Multilevel Converter Mockup The International Conference on Power Systems Transients (IPST2019), 06/2019, URL, Abstract BELHAOUANE Moez, ZHANG Haibo, COLAS Frédéric, KADRI Riad, QORIA Taoufik, GRUSON François, RAULT Pierre, DENNETIERE Sébastien, GUILLAUD Xavier 
This paper deals with the conception and the development of a detailed EMT Model for MMC based on
experimental results obtained from a mockup. The main purpose is to illustrate how to exploit the performances of EMT simulation tools to develop a detailed model that represents accurately the behaviour of a physical MMC. According to stepbystep identification of the MMC element parameters, the idea is to perform a systematic method, which allows expanding an accurate EMT model considering the behaviour of the prototype and its environment. The first part depicts the MMC topology and the modelling approach of the Halfbridge SubModule (SM) using a detailed IGBTbased model. The second part of the simulation model conception concerns both control levels such as highlevel and lowlevel controllers. The last part of the EMT model conception involves the modelling of measurement process, ADC (Analogue Digital Converter), sensors dynamics, the communication delays and especially the quantization effect. Finally, the obtained results from the final detailed EMT model is compared to the experimental behaviour for different active and reactive powers operating points in order to prove the effectiveness and the capability of the EMT modelling to reach a detailed and accurate model. 
[10] Tuning of AC voltagecontrolled VSC based Linear Quadratic Regulation IEEE PowerTech19, 06/2019, Abstract QORIA Taoufik, LI Chuanyue Li, OUE Ko, GRUSON François, COLAS Frédéric, GUILLAUD Xavier, PREVOST Thibault 
In the near future, power converters will be
massively introduced in transmission grids due to renewable
energy sources and high voltage direct current (HVDC)
increase. Voltage Source Converter (VSC) control laws assume
that Synchronous Generators (SGs) build a stiff AC voltage
which allows the synchronization of converters. This is one of
the major reasons that limit the high integration of currentsource
converters in transmission grid. This constraint is no
longer relevant when power converters operate as a voltage
source based on the gridforming concept. This concept uses an
inner cascaded PI controllers in order to regulate the output AC
voltage. However, it is difficult to tune its controller parameters
for stable operation in gridconnected mode. This paper
proposes an alternative statefeedback control with integral
compensator based linear quadratic regulation (LQR) in order
to ensure a stable operation and to get a better AC voltage
transient and good decoupling between reactive and active
power. The proposed control will be fully analyzed and
compared to conventional methods. 
[11] Mixed integer quadratic programming receding
horizon microgrid supervisor 2019 IEEE Milan PowerTech, 06/2019, Abstract LEGRY Martin, COLAS Frédéric, DIEULOT JeanYves, SAUDEMONT Christophe 
This paper proposes to optimize the real time operation
of a microgrid controlled with a twolayer Model Predictive
Controller supervisor. Based on the classical decomposition of
control level, the proposed supervisor tracks longterm economic
references from a classical economic optimization routine. The
optimization problem is formulated as a Mixed Integer Quadratic
Problem and uses the different power references as levers to reach
this optimum and maintain the state of the microgrid within
limitations. In addition, it is able to minimize the grid losses. 
[12] A priori error estimation of the structurepreserving modal model reduction by state residualization of a grid forming converter for use in 100% power electronics transmission systems 15th IET International Conference on AC and DC Power Transmission (ACDC 2019), 02/2019, URL COSSART Quentin, COLAS Frédéric, KESTELYN Xavier 
[13] Inertia effect and load sharing capability of grid forming converters connected to a transmission grid 15th ACDC19, 02/2019, Abstract QORIA Taoufik, GRUSON François, COLAS Frédéric, DENIS Guillaume, PREVOST Thibault, GUILLAUD Xavier 
The virtual synchronous machine concept (VSM) has been developed initially to reproduce the synchronous machine stabilizing effect by providing inertia with the emulation of swing equation, whereas droop control is developed initially to ensure load sharing and has no inertia. An introduction of a low pass filter to droop control has been motivated to filter the active power measurement and ensures a time decoupling with the inner control loops, whereas, this lowpass filter can also provide inertia to the system. This functionality is limited due to its negative impact on the active power dynamic. This paper proposes an analysis of the conventional droop control by showing its limitations and proposes an improved inertial droop control that allows providing the inertia to the system and ensures a good dynamic behavior of the active power at once in simple manner, and without modifying the load sharing capability. The results obtained are compared to the conventional method (Droop control and VSM) in various topologies in order to show the relevance of the proposed method. 
[14] Experimental Validation of a Model Predictive Control Strategy on a Threeterminal VSCHVDC Mockup 15th International Conference on AC and DC Power Transmission, 02/2019, URL, Abstract BELHAOUANE Moez, ALMAKSOUR Khaled, PAPANGELIS Lampros, COLAS Frédéric, PREVOST Thibault, GUILLAUD Xavier, VAN CUTSEM Thierry 
The subject of this paper is the experimental validation of a recently proposed advanced control scheme for Voltage Source
Converters (VSC) based on Model Predictive Control (MPC). The main purpose of the investigated advanced controller is the
frequency support from an AC grid to another after significant disturbance through HVDC Grid. The paper reports on the
implementation methodology on a smallscale 3terminal DC mockup grid consisting of several physical lowscale VSCs,
actual DC cables. These components are coupled with realtime simulation tools simulating the adjacent AC grids. The
different steps for the validation process of the MPC strategy are illustrated, starting from offline simulation based on a
model of the DC grid, up to the actual implementation of the controller in the mockup of the DC grid. 
[15] Control Design of MMC prototype based on OP 5600 Real Time Simulation and eMEGASIM opalrt’s 10th International conference on realtime Simulation, 11/2018, Abstract VERMEERSCH Pierre, BELHAOUANE Moez, STANKOVIC Nikola, COLAS Frédéric, GUILLAUD Xavier 
Over the last 15 years, VSCbased HVDC (High Voltage Direct Current) has become a mature technology for HVDC transmission schemes. The Modular Multilevel Converter (MMC) represents the recent development among the diverse available topologies of VSC and is allegedly the most promising solution today. In fact, the MMC topology offers significant benefits compared to the traditional twolevel VSC (Voltage Source Converter), such as lower losses, distributed storage of capacitive energy, improved scalability to higher voltage ratings, a modular design, low total harmonic distortion and, hence, the potential lack of passive fillers on the ACside of the converter. For the control design, some simplifying assumptions are made to derive an energy based Average Arm Model (AAM) that takes into account the internal dynamics (i.e. the total energy stored in the converter) which do not exist in the 2level VSC, as well as the AC and DC side dynamics. This additional internal dynamics implies that the control system of the converter must possess additional control loops that govern the DC current and the total amount of stored energy in the SM capacitors of the MMC. The total stored energy in the MMC is then decoupled from the DC bus, but can also be potentially shared depending on the reference signal of the energy control loop. So, the Energybased controller strategy is introduced, where extra control loops in cascade are added to regulate the dynamics of interest.
In this work, an energy based control method is developed for the OPALRT’s 10 levels MMC prototype model (5 kW – 400 V). Only the highlevel control is proposed and implemented thanks to real time simulation model on the CPU and ARTEMiS solver based on StateSpace Nodal Solver.
As mentioned above, the energybased control is based on the possibility to control the AC and DC power separately. Thus, if the power that flowing through the converter is controlled by the AC (resp. DC) power reference, it will be possible to drive the energy level thanks to the other power reference DC (resp. AC). Therefore, to control globally the MMC inner dynamics and state space variables, additional controllers should be added. Thereby, energy based controls have been developed where all the state variables are controlled. In this configuration, the highlevel control is composed of outer and inner closed loop controls, which allow controlling the power and the internal MMC energy.
Then, based on the designed energybased controller, the OPALRT’s MMC prototype model has been simulated under different operation conditions arising a good performance in steady state as well as during transients.
Moreover, the advantages of the Perunit approach such as the control design as well as the power converter sizing have been carried out across this work. Thus, the perunit approach is performed on one hand for high voltage characteristic of MMC where the perunit parameters are derived from EMTP library (based on INELFE project) and on the other hand for the low scale OPALRT mockup. As conclusion, the perunit approach can be used for designing the control as previously said but it can be also very useful for the sizing process of the converter. While the perunit approach has been used for many years for the classical power system elements (transformer, synchronous machines), it can be extended also to the sizing of power converter. So, in this work, the perunit quantities of the main elements (capacitor, inductances) will be highlighted. Then, the high voltage characteristic will be considered as a reference and the low voltage characteristics will be compared and some conclusions will be underlined. 
[16] Stochastic power flow of distribution networks including dispersed generation system 2018 IEEE PES Innovative Smart Grid Technologies Conference Europe (ISGTEurope), pages. 16, 10/2018, URL, Abstract BUIRE Jérôme, COLAS Frédéric, DIEULOT JeanYves, DE ALVARO GARCIA Léticia, GUILLAUD Xavier 
The insertion of stochastic renewable energies in distribution grids generates important voltage fluctuations. However, the influence of the On Load Tap Changer and Distributed Generators (DGs) controllers, and specifically the existence of deadbands in the control laws, has been seldom evaluated. Under the assumptions of Gaussian inputs and a linear model of the grid, it is shown that node voltages can be approximated either by Gaussian variables or sums of truncated Gaussian variables. A procedure is necessary to select the Probability Density Function (PDF) which fits best each node voltage. A signal based method and another algorithm relying on the grid topology are presented and compared when the modeling is applied to a real distribution grid. The model is accurate and can be used for confidence level or chanceconstrained optimization of control parameters. 
[17] A Twolayer Model Predictive Control based secondary control with economic performance tracking for islanded microgrids Conférence IECON 2018, 10/2018 LEGRY Martin, COLAS Frédéric, DIEULOT JeanYves, SAUDEMONT Christophe 
[18] Modeling and Control of the Modular Multilevel Converter connected to an inductive DC source using Energetic Macroscopic Representation EPE'18, 09/2018, Abstract QORIA Taoufik, GRUSON François, DELARUE Philippe, LE MOIGNE Philippe, COLAS Frédéric, GUILLAUD Xavier 
The use of DC transmission is particularly advantageous for longdistance transmission and interconnection of asynchronous AC networks. Several converter topologies can be used for HVDC. Multilevel Modular Converters (MMCs) are the most favored given their technological advantages over other converters topologies. Due to their industrial maturity, they have become essential for all AC / DC conversion. So far, they have always been studied with a voltage source on DC side. However, when the converter is equipped with DC breaker, a series inductor is associated to limit current variations. This has consequences in terms of modeling and control determination. This article aims to propose a modification of the control law in order to take into account this inductor. To facilitate the control organization, the Energetic Macroscopic Representation (EMR) is used. 
[19] Simplified converters models for the analysis and simulation of large transmission systems using 100% power electronics 20th European Conference on Power Electronics and Applications, EPE 2018 ECCE Europe, 09/2018, URL COSSART Quentin, COLAS Frédéric, KESTELYN Xavier 
[20] Confidencelevel optimization in distribution grids for voltage droop controllers tuning 2018 Power Systems Computation Conference (PSCC), pages. 17, 06/2018, URL, Abstract BUIRE Jérôme, COLAS Frédéric, DIEULOT JeanYves, DE ALVARO GARCIA Léticia, GRENARD Sébastien, GUILLAUD Xavier 
This paper deals with a centralized tuning of the local controllers parameters in a distribution grid with many Distributed Generators. The optimal controllers settings are obtained by minimizing the confidence level of voltage specification violations. The confidence level optimization problem uses Gaussian uncertainties of shortterm forecasting and OLTC errors along with an accurate linear power flow approximation. Considering these assumptions, the optimization problem is shown to be convex and the characteristics of uncertainties are reduced to their means and standard deviations. The proposed method optimizes the full network while keeping the drooplike industrial structure of the controllers and allows to consider feeders which can have low and high voltages. The merits of the method are illustrated via a modified real distribution network showing a decrease of voltage variances and violations. 
[21] Tuning of cascaded controllers for robust gridforming Voltage Source Converter Power Systems Computation Conference, 06/2018, Abstract QORIA Taoufik, GRUSON François, COLAS Frédéric, GUILLAUD Xavier 
From the origin of the grid, energy has been delivered to electrical loads mainly by synchronous machines. All the main rules to manage the grid have been based on the electromechanical behavior of these machines which have been extensively studied for many years. Due to the increase of HVDC link and renewable energy sources as wind turbine and PV, power converters are massively introduced in the grid with a fundamentally different dynamic behavior. Some years ago, they were connected as simple power injector. Then, they were asked to provide some ancillary services to the grid, in the future, grid forming capability will be required. Even if gridforming converters had been extensively studied for microgrids and offshore grids, it has to be adapted to transmission grid where the topology may be largely modified. This paper presents an algorithm for calculating the controller parameters of a gridforming converter which guarantee a stable behavior for many different configurations of the grid. 
[22] Simplified model of droopcontrolled MTDC grid — Influence of MMC energy management on DC system dynamics PSCC 2018, 06/2018, Abstract FREYTES Julian, GRUSON François, COLAS Frédéric, RAULT Pierre, SAAD Hani, GUILLAUD Xavier 
The interconnections of offshore wind farms have
raised the interest of MultiTerminal DC (MTDC) grids with voltage source converters, specifically with the Modular Multilevel
Converter (MMC) topology. For controlling the DC bus voltage,
the droop control strategy proves to be one of the most effective
since it allows a shared effort between the different converters
connected to the DC grid. Furthermore, these MTDC grids may
likely result in multivendor schemes, where each converter could
have different control strategies among them. Specially on the
way that the internal energy of the MMC is managed, which
may have an important impact on the DC voltage dynamics.
This paper proposes a simplified model to represent the dynamic
behavior of the DC grid including converters which highlights
the droop gain and the energy management of the converter as
main influential parameters. The performance of this model was
assessed by comparisons with EMT simulations on a representative case study with different parameters. 
[23] PowerHardwareIntheLoop simulation of VSCHVDC based threeterminal DC mockup Power Systems Computation Conference 2018, 06/2018, Abstract ALMAKSOUR Khaled, AKKARI Samy, BELHAOUANE Moez, COLAS Frédéric, GUILLAUD Xavier 
The frequency support provided by a DC grid to an interconnected AC grid and integrated in VSCHVDC controller is studied in this paper. The advantages of a combined control of voltage droop and frequency droop are investigated on a hybrid AC/DC system for the case of a sudden loss of large generation unit in the AC grid. The coupling between both droops control and the correction factor of the frequency droop coefficient are discussed. An experimental validation on VSC converter prototypes and under realistic operation conditions is conducted using PowerHardwareIntheLoop simulation. The practical results showed a good match with the theoretical calculation and confirmed the offline simulation results presented in previous work. 
[24] Improved real time operation of microgrids with integrated economic constraints CIRED Microgrid Workshop 2018, 06/2018 LEGRY Martin, COLAS Frédéric, DIEULOT JeanYves, SAUDEMONT Christophe 
[25] Model Reduction of Converters for the Analysis of 100% Power Electronics Transmission Systems IEEE International Conference on Industrial Technology 2018, 02/2018, URL COSSART Quentin, COLAS Frédéric, KESTELYN Xavier 
[26] Combination of linear power flow tools for voltages and power estimation on MV networks CIRED 2017, 06/2017, URL, Abstract BUIRE Jérôme, GUILLAUD Xavier, COLAS Frédéric, DIEULOT JeanYves, DE ALVARO GARCIA Léticia 
European Grid codes define new network management rules. In order to answer these decrees, it is important to estimate accurately the voltages and powers inside distribution networks. The intermittent nature of renewable sources leads to consider stochastic variables in power flow algorithms. A review of power flow methods and their ability to comply with these requirements is done, which shows that computationally demanding nonlinear methods have to be discarded when dealing with stochastic data and considering limited calculation time. A combination of linear methods is proposed, for which average errors in power and voltage are quite low, when applied to a reallife distribution network. The validity domain of the method is also presented. 
[27] Improving Robustness against Grid Stiffness, with Internal Control of an AC VoltageControlled VSC Conférence, 11/2016, Abstract DENIS Guillaume, KESTELYN Xavier, GUILLAUD Xavier, PREVOST Thibault, PANCIATICI Patrick, COLAS Frédéric 
Voltage Source Converterbased transmission grids
might be the future of power system with the increasing share of
interfaced electricity generation. These systems should be able to
support the utility grid autonomously. The present paper focuses
on the VSC output filter design and internal control of filter
states. Nested AC current and voltage loops are the state of the
art for power converters, controlled as voltage sources, in
Microgrid or UPS applications. These internal controls are
candidates for future industrial implementation at high power
level. However, in a VSC based transmission system, those
controls will face various topologies while requiring robustness
against transient events (load changes, line tripping, etc.). The
following development aims at providing keys for designing a
versatile internal control suitable for VSCbased transmission
system. 
[28] Coordinated predictive control in active distribution networks with HV/MV reactive power constraint 2016 Innovative Smart Grid Technologies  Europe (ISGT Europe 2016), 10/2016 MORIN Juliette, COLAS Frédéric, GRENARD Sébastien, DIEULOT JeanYves, GUILLAUD Xavier 
[29] Internal Control Stability Assessment Method of a VSCbased transmission
grid Conférence, 10/2016, Abstract DENIS Guillaume, KESTELYN Xavier, GUILLAUD Xavier, COLAS Frédéric, PREVOST Thibault, PANCIATICI Patrick 
The multiplication of interfaced generation units connected to the utility grid might form VSCbased
transmission grids in a near future. To support the utility grid autonomously, the converters must
provide gridforming capabilities and be connected in parallel. As the structure of a transmission grid
is changing and unknown, these requirements presume a robust local voltage control for each highpower
VSC, to face various network topologies. Indeed, the stability is challenged when voltagecontrolled
VSCs are close to each other, namely, when the tieimpedance is low. The present
contribution describes an impedancebased criterion method as a convenient and effective tool for
assessing the stability of the voltage control of converters in a VSCbased transmission grid. The
method is successfully applied to a typical twoVSC system to anticipate unstable situations 
[30] Dynamic impact of MMC controllers on DC voltage droop
controlled MTDC grids 2016 18th European Conference on Power Electronics and Applications (EPE'16 ECCE Europe), pages. 110, 09/2016, URL, Abstract FREYTES Julian, RAULT Pierre, GRUSON François, COLAS Frédéric, GUILLAUD Xavier 
The Modular Multilevel Converter (MMC) has enhanced the feasibility of MultiTerminal DC grids
(MTDC). For controlling the DC bus voltage in the MTDC grids, the droop control is the most promised
technique. This paper evaluates the dynamic impact of the way of controlling the MMC on the MTDC
grids. Results are compared with a simplified model that highlights the key elements for the dynamic
behavior of the DC bus voltage, the droop parameter and the equivalent DC bus capacitor. 
[31] Optimal Control Design for Modular Multilevel
Converters Operating on MultiTerminal DC Grid 2016 Power Systems Computation Conference (PSCC), pages. 17, 06/2016, URL, Abstract BELHAOUANE Moez, FREYTES Julian, AYARI Mohamed, COLAS Frédéric, GRUSON François, BENHADJ BRAIEK Naceur, GUILLAUD Xavier 
This paper proposes an advanced control strategy
for Modular Multilevel Converters (MMC) integrated in Multiterminal
DC grid. In this present work, a three terminal
MMCMTDC system connecting onshore AC systems with an
offshore wind farm is setup. Firstly, the voltage droop control
associated to the conventional cascaded controllers for MMC
stations is studied, the dynamic behavior of the DC voltage is
analyzed and some drawbacks are outlined. In order to improve
the dynamic behavior of the controlled DC bus voltage and
the stability of MTDC system, an optimal multivariable control
strategy of each MMC converter is proposed and integrated
in a voltage droop controller strategy. The designed advanced
controller allows to improve the overall DC grid stability and
to reach the droop values designed on static considerations with
acceptable dynamic behavior. By means of numerical simulations
in EMTPRV software, it is shown that the proposed control
strategy performs well the stability of MTDC grid with 400
level model for MMC compared with the classic existing control
methods. 
[32] Coordinated control for multi terminal DC grids
connected to offshore wind farms 2016 IEEE 17th Workshop on Control and Modeling for Power Electronics (COMPEL), pages. 18, 06/2016, URL, Abstract RAULT Pierre, FREYTES Julian, GUILLAUD Xavier, COLAS Frédéric, SAAD Hani, DESPOUYS Olivier, NGUEFEU Samuel 
This article deals with power flow coordination of
a HVDC grid used to connect offshore wind farms to several
mainland grids. The coordination of the DC grid is achieved
thanks to a centralized control which monitors and sends proper
setpoints to manage power flow. This controller is equipped with
a dedicated algorithm which enables to guarantee as much as
possible the desired power transfer and cope with wind power
forecast errors. Moreover, this HVDC grid controller is used as
interface for the AC transmission system operator to redistribute
power flow among grid side converter stations in order to derisk
AC contingencies and avoid wind power spillage. Simulations
results obtained from an EMT model of a fiveterminal MTDC
grid with Modular Multilevel Converters prove the effectiveness
of the proposed methodology in normal operation as well as the
system restoration after a wind farm disconnection. 
[33] Control of MMC converter integrated in HVDC link based on quadratic optimization approach IEEE 17th Workshop on Control and Modeling for Power Electronics (COMPEL'16), 06/2016, URL BELHAOUANE Moez, COLAS Frédéric, GRUSON François, GUILLAUD Xavier 
[34] Geometrical parametric model order reduction of transmission lines EMF 2016, Lyon, France, 04/2016 PIERQUIN Antoine, HENNERON Thomas, LE MENACH Yvonnick, COLAS Frédéric 
[35] Losses estimation method by simulation for the modular multilevel converter Electrical Power and Energy Conference (EPEC), 2015 IEEE, pages. 332338, 10/2015, URL, Abstract FREYTES Julian, GRUSON François, DELARUE Philippe, COLAS Frédéric, GUILLAUD Xavier 
The modular multilevel converter (MMC) is the most promising solution to connect HVDC grids to an HVAC one. The installation of new equipment in the HVDC transmission systems requires an economic study where the power losses play an important role. Since the MMC is composed of a high number of semiconductors elements, the losses estimation becomes complex. This paper proposes a simulationbased method for the losses estimation that combines the MMC averaged and instantaneous model in a modular way. The method brings the possibility to compare performances for different modules technologies as well as different high and low level control techniques. The losses characteristics within the MMC are also discussed. The passive losses are taken into account for the first time. 
[36] Impact of control algorithm solutions on Modular Multilevel Converters electrical waveforms and losses EPE ECCE Europe 2015, 09/2015, URL, Abstract GRUSON François, FREYTES Julian, SAMIMI Shabab, DELARUE Philippe, GUILLAUD Xavier, COLAS Frédéric, BELHAOUANE Moez 
Modular Multilevel Converters (MMC) are becoming increasingly popular with the development of HVDC connection and, in the future, Multi Terminal DC grid. A lot of publications have been published about this topology these last years since it was first proposed. Many of them deal with converter control methods, other address the method of estimating losses. Usually, the proposed losses estimation techniques are associated to simple control methods For VSC (Voltage Sources Converters) topology, the losses minimization is based on the limitation of the RMS currents values. This hypothesis is usually extended to the control of MMC, by limiting the differential currents to their DC component, without really being checked. 
[37] Review on Potential Strategies for Transmission System Based on Power Electronics Interfaced Voltage Sources IEEE PES GENERAL MEETING, 07/2015, URL, Abstract DENIS Guillaume, PREVOST Thibault, PANCIATICI Patrick, KESTELYN Xavier, COLAS Frédéric, GUILLAUD Xavier 
In the near future, transmission grids will include an increasing share of directly connected voltage source converters. These systems should be able to support the utility grid autonomously. The present paper reviews the most popular approaches to address the challenge of proper load sharing amongst multiple parallel inverters applied to the utility grid case. Originally developed for Microgrid or UPS applications, these decentralized controls mimic a conventional synchronous generator based system steadystate behavior and showed suitable effectiveness to reach the desired operating point. However, the operations at the transmission grid level bring additional stress on the converters and require transient capabilities. Physical limitations of semiconductor based converters fundamentally differ from a conventional synchronous generator. Therefore the paper illustrates how the usual real power controls may lead to undesirable behavior during transient events. This raises new issues for reliable operations of interconnected VSCs at transmission level. 
[38] Determination and origins of reactive power flows in HV/MV susbtations 23rd International Conference and exhbition on electricity distribution (CIRED), 06/2015, Abstract MORIN Juliette, COLAS Frédéric, GUILLAUD Xavier, GRENARD Sébastien 
This paper analyses the evolution of reactive power flows at the interface of French transmission and distribution systems. The influence of the insertion of distributed generation (DG), the replacement of medium voltage (MV) overhead lines by underground cables as well as the evolution of the reactive part of the load are investigated. Numerical simulations are performed with a real French HV/MV substation for illustrative purpose. The technical consequences of such evolutions are investigated, e.g. the saturation of On Load Tap Changers (OLTC). The use of DGs connected to the MV network to regulate reactive power exchange between Transmission System Operator (TSO) and Distribution System Operator (DSO) is also discussed. 
[39] Rules based voltage control for distribution network combined with DSOTSO reactive power exchanges limitations Powertech, IEEE 2015 Eindhoven, 06/2015, Abstract MORIN Juliette, COLAS Frédéric, GUILLAUD Xavier, GRENARD Sébastien, DIEULOT JeanYves 
This article deals with the evolution of voltage and reactive power control strategies in distribution networks with distributed generation. First a comprehensive review of voltage control and reactive power management techniques is given. The gap between actual or shortterm industrial possibilities of distribution grids and techniques proposed in literature is highlighted. A realistic control based on local rules using the reactive power capabilities of distributed generators, capacitor banks and on load tap changer (OLTC) voltage setpoint is then presented. Its objective is to control both distribution network voltages and reactive power flows at the Transport System Operator (TSO)  Distribution System Operator (DSO) interface. The proposed control allows limiting OLTC bounds and conflicts between local rules. At last, this paper presents simulations results based on French MV distribution network in order to depict the efficiency of such a control. 
[40] Advanced metering infrastructure for realtime coordination of renewable energy and electric vehicles charging in distribution grid CIRED Workshop, "Challenges of implementing Active Distribution System Management", Rome, 1112 June 2014, 06/2014 BOUALLAGA Anouar, KADRI Riad, ALBINET V, DAVIGNY Arnaud, COLAS Frédéric 
[41] Power Hardware In the Loop Simulation Of Wind Farm Contribution To Grid Frequency Control EPE, September 2013, Lille, France, 09/2013 ANDRIAMALALA R.N, WANG Ye, GUILLAUD Xavier, COLAS Frédéric, FRANCOIS Bruno 
[42] Experimental Assessment Of the Wind Turbine Contribution to the Primary Frequency Control in an Isolated Power system IEEE PES International Conference POWERTECH 2013, Grenoble, 1620 juin 2013, 06/2013 ANDRIAMALALA R.N, YANG Ye, COLAS Frédéric, FRANCOIS Bruno, GUILLAUD Xavier 
[43] Investigation on interactions between AC and DC grids IEEE PES International Conference POWERTECH 2013, Grenoble, 1620 juin 2013, 06/2013 RAULT Pierre, GUILLAUD Xavier, COLAS Frédéric, NGUEFEU Samuel 
[44] Supervisory predictive control of a hybrid solar panels, microturbine and battery power generation plant
Power Plants and Power Systems Control Conférence, Vol. 8, N°. 1, pages. 375380, 07/2012, Abstract CHALAL Lamine, DIEULOT JeanYves, DAUPHINTANGUY Geneviève, COLAS Frédéric 
The main objective of this work is to design a supervisory predictive controller which optimizes the power flow of a renewable hybrid system (solar panels, microturbine and battery. Short time predictions of the solar power and the power reference will be embedded in the supervisor. Unlike expertisebased algorithms, the design of a generic and flexible strategy based on dynamic models is proposed. The performance index integrates the environmental impact, the cost of fuel, battery cycling and the energy delivery. Simulations and a realtime application in a HardwareintheLoop plant are carried out to illustrate the applicability and effectiveness of the proposed supervisory predictive control design. 
[45] Realtime simulation of a medium scale distribution network : decoupling method for multiCPU computation Conference COMPENG, Aachen, 1113 juin 2012, 06/2012 TENINGE A, BESANGER Y, COLAS Frédéric, FAKHAM Hicham, GUILLAUD Xavier 
[46] Distributed Power Management System of Virtual Power Plants IEEE ISGT, Manchester, 57 December 2011, 12/2011 FAKHAM Hicham, COLAS Frédéric, GUILLAUD Xavier 
[47] FPGA Implementation of a General Space Vector Approach on a 6Leg Voltage Source Inverter IECON 2011  IEEE International Conference On Industrial Applications of Electronics, N°. 37, pages. 34823487, 09/2011, Abstract SANDULESCU AlexandruPaul, IDKHAJINE Lahoucine, CENSE Sebastien, COLAS Frédéric, KESTELYN Xavier 
A general algorithm of a Space Vector approach is implemented on a 6leg VSI controlling a PM synchronous machine with three independent phases. In this last case, the necessity of controlling the zerosequence current motivates the choice of a special family of vectors, different of this one used in Pulse Width Modulation (PWM) intersective strategy and in common Space Vector PWM (SVPWM). To preserve the parallelism of the algorithm and fulfill the execution time constraints, the implementation is made on a Field Programmable Gate Array (FPGA). Comparisons with more classical 2level and 3level PWM are provided.
Keywords – FPGA, Modulation strategies, Space vector, Multiphase machine, Multiphase, Multileg.

[48] HVDC Meshed grid : Control and Protection of a Multiterminal HVDC System CIGRE 2014, 08/2011, Abstract DESCLOUX Justine, RAULT Pierre, NGUEFEU Samuel, GUILLAUD Xavier, COLAS Frédéric 
This paper deals with the technical feasibility of a multiterminal VSCHVDC (MTDC) grid in the
North Sea, connecting several offshore wind farms to several substations of the onshore AC grid. A
topology of meshed DC grid with five terminals is chosen. Normal operations as well as fault events
are investigated in order to estimate the flexibility and the reliability of the MTDC grid. Therefore, this
study will comprise two distinct parts. First, the paper goes through the control performance of the
system and then, the protection scheme is discussed. The simulation of the considered model is
developed and will be computed using EMTPRV. 
[49] Realtime Simulation of MultiAgent System for Decentralized Voltage Regulation in Distribution Network IEEE General Meeting Detroit, 2429 July 2011, 07/2011 FAKHAM Hicham, COLAS Frédéric, GUILLAUD Xavier 
[50] Parameters tuning methodology of fuzzy logic supervisors for hybrid generating systems with experimental designs 10th International Conference on Modeling and Simulation of Electric Machines, Converters and Systems, ELECTRIMACS 2011, Paris, 68 juin 2011, 06/2011 ALKHALIL Firas, COLAS Frédéric, ROBYNS Benoît 
[51] Energy Management Strategy for Commercial Buildings Integrating PV and Storage Systems Sustainability in Energy and Buildings Conference, SEB’11 Marseilles 13 Juin 2011, 06/2011 ZHANG He, DAVIGNY A, SPROOTEN Jonathan, ROBYNS Benoît, COLAS Frédéric 
[52] Secant generalized method minimizing the fuel and emissions costs in a power station of small cogeneration multimachines International Conference on Renewable Energy and EcoDesign in Electrical Engineering, IREED, Lille, 2324 mars 2011, 03/2011 ALKHALIL Firas, COLAS Frédéric, ROBYNS Benoît 
[53] Virtual Resistance Principle for the Overcurrent
Protection of PWM Voltage Source Inverter IEEE PES Conference on Innovative Smart Grid Technologies (ISGT) GothenburgSweden 1113/10/ 2010, 10/2010 SALHA Fouad, COLAS Frédéric, GUILLAUD Xavier 
[54] MultiAgent System for Distributed Voltage Regulation of Wind Generators Connected to Distribution Network IEEE PES Conference on Innovative Smart Grid Technologies Europe October 1113, 2010, Gothenburg, Sweden, 10/2010 FAKHAM Hicham, AHMIDI Amir, COLAS Frédéric, GUILLAUD Xavier 
[55] Dynamic Behavior Analysis of a Voltage Source Inverter for MicroGrid Applications IEEE PES General Meeting ,MinneapolisUSA,July 25  29, 2010, 07/2010 SALHA Fouad, COLAS Frédéric, GUILLAUD Xavier 
[56] Realtime simulation: the missing link in the design process of advanced grid equipment IEEE Power & Energy Society General Meeting 2010, Minneapolis, USA, 2529 July 2010, 07/2010, Abstract WANG Ye, DELILLE Gauthier, GUILLAUD Xavier, COLAS Frédéric, FRANCOIS Bruno 
This paper describes a design process of advanced grid equipment including both dynamic simulations and powerhardwareintheloop. A case study concerning the insertion of an energy storage system in a large isolated grid is used as an illustrative example. First, the methodology developed to achieve a realtime simulation of the studied grid from its original dynamic model is presented. The realtime platform used within the framework of this project is based on the RTLAB environment and is interfaced with real ultracapacitors through a power amplifier. Some experimental results are analyzed in the final part. The advantages of this methodology including powerhardwareintheloop are emphasized by illustrating its contribution to dynamic model validation and the obtained improvement in control system performances. 
[57] A Multiagents System for a Distributed Power Management of Micro Turbine Generators Connected to a Grid Conference on Control Methodologies and Technology for Energy Efficiency (CMTEE) 2010, Vilamoura, Portugal, March 2931, 2010, 03/2010 FAKHAM Hicham, DONIEC A, COLAS Frédéric, GUILLAUD Xavier 
[58] Grid Connected Inverter Behavior with an Output LC Filter under Voltage Sag Operation Proceedings of the 13th Conference EPE 2009, Barcelone, 8 – 10 september 2009, 09/2009 SALHA Fouad, COLAS Frédéric, GUILLAUD Xavier 
[59] A Modified Vector Control Strategy for DFIG Based Wind Turbines to RideThrough Voltage Dips 13th European Conference on Power Electronics and Applications: EPE’2009, Barcelona, Spain, september 2009, 09/2009 PENG Ling, COLAS Frédéric, FRANCOIS Bruno, LI Y 
[60] Dynamic Performance Analysis of a LC Filter Grid Connected Gas Turbine under Voltage Sag Operation Electromotion Lille 2009, 07/2009 SALHA Fouad, COLAS Frédéric, GUILLAUD Xavier 
[61] Bond Graph based control of a three phase inverter with LC filter ECMS 2009, Madrid, 06/2009 SANCHEZ Roberto, COLAS Frédéric, DAUPHINTANGUY Geneviève, GUILLAUD Xavier 
[62] Fuel consumption minimization of a cogeneration system multi machines associated with a photovoltaic Proceedings of the International Conference on Renewable Energies and Power Quality, ICREPQ09, Valence, 1517 april 2009, 04/2009 DONDAS M, ALKHALIL Firas, DEGOBERT Philippe, COLAS Frédéric, ROBYNS Benoît 
[63] Fuel consumption optimization of a multimachines microgrid by secant method combined with IPPD table Proceedings of the International Conference on Renewable Energies and Power Quality, ICREPQ09, Valence, 1517 april 2009., 04/2009 ALKHALIL Firas, DEGOBERT Philippe, COLAS Frédéric, ROBYNS Benoît 
[64] Supervision of a hybrid system based on photovoltaic arrays and supercapacitors Proceedings of the International Conference on Power Engineering, Energy and Electrical Drives, POWERENG09, Lisbonne, 1820 mars 2009., 03/2009 DONDAS M, ALKHALIL Firas, DEGOBERT Philippe, COLAS Frédéric, ROBYNS Benoît 
[65] Comparison of fast frequency estimation methods for trajectory planning tuning IEEE conference on Advanced Motion Control 2008, 01/2008 DIEULOT JeanYves, COLAS Frédéric, BARRE PierreJean, FIRAS FEKI Mohamed 
[66] Indirect Adaptive learning of Acceleration feedback control for Chained Multiple MassSpringDamper Systems ICRA’07 IEEE International Conference on Robotics and Automation, 04/2007, URL, Abstract DIEULOT JeanYves, COLAS Frédéric, BARRE PierreJean, BORNE Pierre 
An indirect Iterative Learning algorithm has shown to be able to update the parameters of an acceleration feedback controller for flexible manipulators. The fine estimation of the masses of a chain of massspringdampers units allows the simultaneous tuning of both the feedback controller and the trajectory generation. This algorithm has been validated on an industrial robot arm. 
[67] A Quantitative Evaluation Of The NonMinimum Phase Phenomenon For A Robot Arm CESA ’2006 IEEE Multiconference on "Computational Engineering in Systems Applications", 10/2006, URL, Abstract COLAS Frédéric, BARRE PierreJean, DIEULOT JeanYves 
Abstract  The nonminimum phase phenomena of a robot’s arm modelled by a set of EulerBernoulli beams clamped on a moving cart is demonstrated. Modal analysis is used to derive the exact eigensolutions which verify the described geometric boundary conditions. The equations of motion are determined using the Assumed Mode Method. The influence of geometrical and mechanical parameters such as the thickness of the cross sections of the beams, or the beam length, is discussed using numerical simulations. The overall results, with an application to a real robot, show that one has to take the nonminimum phase problem into consideration when designing a flexible mechanical structure. 
[68] Dynamics modeling and Causal Ordering Graph representation of a non minimum phase flexible arm fixed on a cart Wseas International Conference on Dynamical Systems and Control (Control’05), 11/2005 COLAS Frédéric, DIEULOT JeanYves, BARRE PierreJean, BORNE Pierre 
[69] Use of the COG representation to control a robot with acceleration ICINCO 2005, 2nd International Conference on Informatics in Control, Automation and Robotics, N°. 2, pages. 2531, 09/2005 COLAS Frédéric, DUMETZ Eric, BARRE PierreJean, DIEULOT JeanYves 
[70] Influence of the frequency support provided by a gridforming controlbased wind turbine on the loading of its mechanical system Conférence, A paraître, Abstract AVAZOV Artur, COLAS Frédéric, BEERTEN Jef, GUILLAUD Xavier 
This paper proposes the analysis of the frequency support from a TypeIV wind turbine interfaced to the grid via a gridforming converter. The frequency support including the inertial response and the fast primary frequency support is implemented by integrating a gridforming control to the control a backtoback converter. Knowing that the inertial response from a gridforming converter can be tuned by varying the inertia constant of a gridforming control, it is possible to extract different amounts of kinetic energy from the rotating masses of a wind turbine and positively impact the grid frequency dynamics during a grid frequency event. However, the increased inertial response may lead to an increased loading imposed on the mechanical components of a wind turbine. To elaborate and verify these statements, the analysis is aimed at two objectives. Firstly, it is estimated through time domain simulations whether the inertial response from a gridforming controlbased wind turbine has a significant active power contribution or can be neglected compared to the share of the primary frequency support. Secondly, based on the analyzed impact of the inertial response on the grid frequency and the mechanical loading, a value of the inertia required from a wind turbine with a gridforming converter is recommended. 
ACN Conférence nationale avec acte 
[1] Interaction entre le contrôle, le dimensionnement, et les performances du Convertisseur DCDC Modulaire Multiniveaux (M2DC) Symposium de Génie Electrique 2020, SGE 2020, 11/2020, Abstract GRUSON François, VERMEERSCH Pierre, LI Yafang, DELARUE Philippe, LE MOIGNE Philippe, COLAS Frédéric, GUILLAUD Xavier 
Le convertisseur DCDC Modulaire Multiniveaux (M2DC) est une topologie attrayante de convertisseur DCDC non isolée pour les réseaux haute tension à courant continu (HVDC). Cet article présente dans un premier temps, le modèle et la commande du M2DC. Une étude de l’utilisation des degrés de liberté phares est menée dans un second temps pour réaliser une analyse de leurs impacts sur le dimensionnement des éléments du convertisseur tels que les condensateurs de sous modules ainsi que sur les pertes liées aux semiconducteurs 
[2] Modèles réduits de convertisseurs pour l’étude de réseaux 100% électronique de puissance Symposium de Génie Électrique SGE 2018, 07/2018 COSSART Quentin, COLAS Frédéric, KESTELYN Xavier 
[3] Contrôle du Convertisseur Modulaire Multiniveaux connecté à une source DC inductive Symposium de Génie Electrique 2018, SGE 2018, 07/2018, Abstract QORIA Taoufik, GRUSON François, DELARUE Philippe, LE MOIGNE Philippe, COLAS Frédéric, GUILLAUD Xavier 
L'utilisation de la transmission DC est particulièrement avantageuse pour la transmission à longue distance et l'interconnexion des réseaux AC asynchrones. Plusieurs topologies de convertisseur peuvent être utilisées pour le HVDC. Les convertisseurs modulaires multiniveaux (MMC) sont les plus favorisés étant donné leurs avantages technologiques par rapport aux autres topologies de convertisseurs. Du fait de leur maturité industrielle, ils se sont imposés maintenant pour tous les convertisseurs AC/DC à transistors de forte puissance. Jusqu'ici, ils ont toujours été étudiés avec une source de tension côté DC. Or, lorsqu'ils sont équipés de DC breaker, on associe une inductance en série pour limiter les variations de courant. Ceci a des conséquences en terme de modélisation puis de détermination de la commande. Cet article a pour objectif de proposer une modification de commande afin de prendre en compte cette inductance. 
[4] Conception, réalisation et test d’un convertisseur Modulaire Multiniveau SGE 2016, 06/2016, Abstract GRUSON François, KADRI Riad, COLAS Frédéric, GUILLAUD Xavier, DELARUE Philippe, BERGÉ Marta, DENNETIERE Sébastien, OULD BACHIR Tarek 
Le Convertisseur Modulaire Multiniveaux (MMC) est une structure d’électronique de puissance utilisée dans des applications de variation de vitesse des machines électrique haute tension mais aussi des applications de transport de l’électricité à très haute tension et courant continu. La structure MMC présente beaucoup d’avantages tels que sa modularité, l’absence de bus DC haute tension et une fréquence de commutation très faible étant donnée le grand nombre de SM. Elle présente aussi des inconvénients comme la complexité de modélisation [2] et de contrôle [3] dû au grand nombre de semiconducteurs à contrôler. Cet article a pour objectifs de présenter le dimensionnement d’un convertisseur MMC de laboratoire ainsi que son système de contrôle, le plus réaliste possible d’une structure échelle une, avec un grand nombre de SM. Le dimensionnement de ce dernier prendra en compte les contraintes et les caractéristiques son fonctionnement dans un réseau HVDC 640kV 1GW. Une architecture de contrôle, contraintes par le nombre de de sous module, sera présentée. Les protocoles de validation des sous modules, d’un demibras puis du convertisseur seront présentés. 
[5] Représentation Energétique Macroscopique
et Diagramme PQ des
Convertisseurs Modulaires Multiniveaux
Symposium de Génie Électrique 2014, 07/2014, Abstract SAMIMI Shabab, GRUSON François, DELARUE Philippe, GUILLAUD Xavier, COLAS Frédéric 
Le système étudié dans cet article est un convertisseur Modulaires MultiNiveaux. Dans une première partie, l’utilisation de la Représentation Energétique Macroscopique (REM) permet de mettre en évidence les couplages importants qui existent au sein de ce système. L’inversion du modèle conduit à une architecture générale de la commande amenant à avoir autant de correcteurs que les variables d’état. Avec la solution proposée, il est possible de contrôler chaque tension de condensateur équivalent. Dans une seconde partie, la méthodologie permettant de déterminer le diagramme PQ du convertisseur MMC est présentée. Quelques points de fonctionnement aux limites de ce diagramme sont validés par simulation. La maitrise des dynamiques ainsi que la connaissance du diagramme PQ sont des étapes nécessaires pour l’intégration de ce type de convertisseur dans un réseau alternatif. 
[6] Method for Small Signal Stability Analysis of VSCMTDC grids Proc. IEEE Power and Energy Society General Meeting, 07/2012, Abstract RAULT Pierre, GUILLAUD Xavier, COLAS Frédéric, NGUEFEU Samuel 
This paper deals with small signal stability analysis of Voltage Source Converter based Multitermial HVDC grids (VSCMTDC). First, a simplified model is used to predict the voltage dynamic behavior. Next, a modular method to build the state space model of the overall MTDC system is described. Model validation is achieved in time domain by a comparison with an electromagnetic simulation in EMTPrv. As concrete example of effective application, a parametric study on the droop value is carried on a 3terminal meshed HVDC grid. This example attests to the effect of the droop parameter on the
stability of the overall system. 
[7] Influence de différentes structures de commande sur le compromis temps/vibration – Application à un robot cartésien 4èmes Assises Machines et Usinage à Grande Vitesse, 06/2006, Abstract COLAS Frédéric, DIEULOT JeanYves, BARRE PierreJean 
Résumé : L’augmentation des performances d’une machine passe obligatoirement par une augmentation de ses sollicitations. Il est alors nécessaire d’améliorer soit sa structure mécanique, soit sa structure de commande. Dans ce dernier cas, le choix d’une structure de commande adaptée peut améliorer les performances et réduire les vibrations venant des modes propres d’un système. Cet article propose une étude comparative de l’influence de différentes commandes sur le compromis temps/vibration. Cette analyse a été réalisée sur un robot cartésien. La liste des commandes retenues est loin d’être exhaustive cependant celles qui font l’objet de cette étude sont utilisables sur les systèmes actuels. Après avoir présenté le système sur lequel repose cette étude, chaque commande retenue est analysée et les résultats expérimentaux obtenus sont tous résumés à la fin du papier. 
AP Autre publication 
[1] Challenges when operating DC grids Revue E tijdschrift, 12/2012, URL, Abstract RAULT Pierre, GUILLAUD Xavier, COLAS Frédéric, NGUEFEU Samuel 
In the context of increasing demand for green energy, offshore wind plants, particularly in the North Sea, are a good
means to meet the challenge and reach 20 % of renewable energies by 2020 in Europe. Since these wind turbines
will be located quite far from the shore; DC links may be needed to transfer the power to the main grid. Instead of
building several independent DC links in the same region, for economic reasons, it seems more advantageous to con
nect these DC links together and create a meshed DC grid among different countries. This idea is attractive but a lot
of technical challenges have to be overcome. Some solutions may be found in the latest technological development,
especially with the evolution of power electronics. However, all the solutions are not found yet.
In this paper, we are presenting the state of the art of Voltage Source Converter (VSC) based HVDC grid technology.
The generic structure of Modular Multilevel Converter (MMC) is presented. The basis of the control methods for a point
topoint link is first analyzed and then extended to a meshed DC grid. We are also presenting the major breakthroughs
still to be done in terms of management and protection of the DC grid. 
INV Conférence invité 
[1] Comparison of Distribution grid modeling using PowerFactory and ePHaSORsim software Conférence, REALTIME 2014 CONFERENCE, MONTREAL, Canada, 06/2014 BOUALLAGA Anouar, ALBINET V, DAVIGNY Arnaud, COLAS Frédéric, COURTECUISSE Vincent, ROBYNS Benoît 
TH Thèse 
[1] Synthèse et réglage de lois de commande adaptées aux axes souples en translation  Application aux robots cartésiens 3 axes Automatique et Informatique Industrielle, 11/2007 COLAS Frédéric 
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