Transient Stability Enhancement Control for VSG Considering Fault Current Limitation and Reactive Power Support Constraints

The virtual synchronous generators (VSGs) have been found to be effective in supporting the voltage and frequency of power systems. However, VSGs may suffer from transient instability and overcurrent under grid fault conditions. Nevertheless, VSGs are required to output necessary reactive power during grid faults in compliance with the latest grid codes. Unfortunately, the internal connections between the transient stability and the fault current limitation, the reactive power support constraint, still leave unknown. To address this issue, this paper proposes a transient stability enhancement method that considers all these constraints. Firstly, the droop coefficient of the reactive power control loop is redesigned to regulate the VSG's current. Secondly, an adaptive control is introduced in the active power control loop to improve the transient power angle stability. Additionally, the design guidelines for various fault scenarios and constraints are proposed. The effectiveness of the proposed parameters regulation method is finally validated through both simulation and experimental results.