Transient Voltage Support Strategy for Grid-Forming PV-ESS Based on Dynamic Reactive Power Compensation

Grid-following control no longer applicable to power system because of the high-proportion level of renewable energy generation, which brings challenges like insufficient reactive-power support, weak voltage-recovery capability during faults. Although the grid-forming photovoltaic integrated energy storage system (PV-ESS) has active support ability, it faces power-angle instability during its transient process. Therefore, this paper study the coupling influence mechanism of reactive-power control loop on transient stability of grid-forming control during grid faults. Reactive power-voltage <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{(Q_{\mathrm{e}}-E)}$</tex> droop control changes <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{P_{\mathrm{e}}-\delta}$</tex> curve, increase system instability in accelerating area and decrease in decelerating area. Then a transient voltage-support strategy based on dynamic reactive-power compensation is proposed. It reconstructs stable-operating range by dynamically adjusting the reactive-power compensation amount. A simulation model is developed based on Matlab/Simulink platform. Simulation results verify the proposed control strategy.