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Grid-Forming control (GFM) plays an increasingly crucial role in modern power grids by ensuring stability and providing inertia, keeping the voltage waveform steady and preventing rapid changes. One of the main challenges in GFM is that it operates as a voltage source, making current control challenging. Since power electronics converters have limited capacity, managing current limitation becomes critical. To address this, certain types of grid-forming embed a current loop (CCGFM); therefore, limiting the current reference can effectively control the current. Despite its effectiveness, a significant issue arises in post-fault states, where current limitation can decrease the stability margin and restrict synchronization. To overcome this challenge, a virtual power-based method has been proposed, which decouples synchronization angle control from current limitation by employing unsaturated current references for power measurement. While effective, continuous current control has been found to reduce the small-signal stability of the system. This paper presents a novel hybrid architecture of Voltage Control Grid-Forming (VCGFM) that improves stability under large disturbances by incorporating the virtual power approach from CCGFM while taking advantage of the small-signal stability superiority of the classical VCGFM by eliminating the impact of current control during normal operation. The proposed method is further validated through experimental testing.

With the increasing penetration of power electronic converters in the power system induced by the energy transition, Grid Forming (GFM) technology emerges as crucial for complementing traditional synchronous generators in fulfilling system needs. All over the world, TSOs have started introducing performance-based requirements to define the desired behaviour of GFM units without prescribing specific technical solutions. Based on these specifications, manufacturers design their grid-connected equipment. However, depending on requirements, challenges may arise in optimizing control strategies without hardware modifications, potentially becoming cost-driving factors. Intellectual property protection limits information disclosure, restricting the guidance available to TSOs during cost–benefit assessments. Academic contributions on GFM control and generic models can bridge the gap, providing a fair portrayal of the general behaviour and then facilitates an open discussion on their ability to meet the requirements and contribute to fulfil system needs. This survey paper provides a comprehensive overview of the perspectives offered by these diverse stakeholders.

The evolving energy mix increasingly integrates variable renewable energy systems into power grids, prompting the exploration of alternative black-start approaches at the distribution network. This study focuses on the use of distributed resources connected via power electronics converters to supply loads at the distribution level through transformers, following a blackout of the transmission system. Energizing transformers generates high unbalanced inrush currents with harmonics due to iron core saturation, posing a significant challenge. Unlike synchronous machines, power electronic converters cannot support large inrush currents. This paper demonstrates a grid-forming control that provides high-quality voltage while protecting the converter by limiting the inrush current. A benchmark is then implemented to illustrate the use of grid-forming to energize multiple transformers during a distributed black-start. It also demonstrates the ability of the proposed grid-forming to synchronize with an existing grid.

Grid-forming control plays an essential role in the modernization of HV electrical transmission grids, particularly in mitigating challenges imposed by large voltage disturbances. In this context, the concept of virtual power has gained prominence as a potential approach that improves stability following such disturbances. This paper illustrates the use of virtual power method in enhancing the large disturbance stability given by the grid-forming control. An adaptive virtual impedance is also proposed to further improve system dynamics. The methods are evaluated through large disturbance stability analysis and time-domain simulations.

In recent years, several works on grid-forming converters in transmission networks have been performed. Since these high voltage grids are mainly inductive, a natural decoupling exists between active and reactive power controls. This decoupling facilitates the design and the performance of the grid-forming controllers. However, in distribution applications, it is well known that the R/X ratio of the line impedance is substantially higher, preventing the system from a natural decoupling effect. This paper proposes an original solution to decouple the control and gives an application to a low voltage connection of a grid-forming converter.

Nowadays, the production of electric energy is evolving towards decentralized systems by an increasingly advanced integration of new active loads such as electric vehicles and renewable energy sources. This energy transition involves the use of power electronics converters to regulate energy exchanges. In this context, this paper brings the L2EP knowledge on grid-forming control developed in a high-voltage context to the ValeoSiemens reversible charger. This comprises two significant differences in the sizing of the system: a lower grid connection impedance and a resistive aspect of the distribution network. To overcome these challenges, this paper proposes two techniques: the virtual impedance to compensate the low value of connection impedance and dynamic decoupling of active and reactive power to consider the resistive effect of the distribution network.