Impact of Voltage Phase Jump on Transient Reactive Power of PV Inverter in LVRT

The transient reactive power support capability of the photovoltaic (PV) inverter during the low voltage ride through (LVRT) period would be the key factor of transient voltage improvement for the power grid with the PV station connected to. A phase jump of the voltage usually arises from the grid fault and lead to the synchronization error of the phase-locked loop (PLL) in a short transient term, which would cause the error of the D-Q Transformation and the error of the control references of the voltage and the current. This paper derives the relationship of the phase changing angle error and the error of the reactive current reference value of the PV inverter and analyzes the influence characteristics of the phase jump caused by different low-voltage faults on the reactive current reference, with or without the consideration of the impact of the real power output in the LVRT. The results show that the phase jump will diminish the transient reactive power support effect of PV inverter to the grid. Finally, the simulation cases are presented to verify the above analysis conclusion.