Influence of Fault Clearing Angle on Temporary Over-Voltage at the Terminal of Grid Following Photovoltaic Inverter

This article presents new results on the impact of fault clearing angle on the temporary over-voltages (TOVs) at the terminal of a grid following (GFol) photovoltaic (PV) inverter during fault recovery. The dynamic behaviour of a GFol inverter heavily depends on the control loops, which are significantly different from synchronous generator controls. Standards and grid codes mandate the GFol inverters of a large-scale PV plant to remain connected and support the grid during and after faults. Once a fault is removed, the GFol inverters enter fault recovery mode, in which they try to reach a steady state. The GFol inverters’ dynamic responses during fault recovery have an impact on the TOVs at the inverter terminal. This article shows that the TOV at the terminal of a GFol inverter during fault recovery depends on the fault clearing angle. This article also shows that the degree of influence of fault clearing angle on TOV depends on the bandwidth of the positive sequence phase-locked loop (PLL) and the dynamic voltage support. A system has been built in PSCAD/EMTDC software to carry out the study. The developed GFol inverter has low voltage ride through, dynamic voltage support and negative sequence current injection functionalities per the IEEE Std 2800-2022. Three-phase faults have been created at the inverter terminal. The fault starting time is kept constant while the fault clearing angle of the phase-A voltage is varied from 0° to 360°. The relevant control parameters of the GFol have been varied to understand the impact of the PLL bandwidth and dynamic voltage support on the TOVs for different fault clearing angles.