Adaptability Study of Under-Voltage Load Shedding Strategies for Grid with Large-Scale Distributed Photovoltaic Generation

Under-voltage load shedding (UVLS), as one of the key measures in emergency control, plays a crucial role in enhancing system voltage recovery and ensuring the safe and stable operation of the power grid. With the increasing penetration of distributed photovoltaic (PV) generators, the effectiveness of traditional UVLS strategies in recovering grid voltage after faults remains unclear, which may risk the voltage stability of the system. This paper develops a model for analyzing UVLS in a power grid with a large-scale integration of distributed PV systems. It provides in-depth analysis from four aspects: the location, low-voltage ride-through (LVRT) capability, control strategies and output characteristics of the PV. The mismatch scenarios and reasons for traditional UVLS strategies are analyzed for a power system with high proportion of distributed PVs. Then, appropriate locations for UVLS tests can be selected by utilizing an improved analytical sensitivity that considers distributed PV systems. Lastly, simulation examples validate that current UVLS strategies are insufficient for the power grid when large-scale distributed PV generation is integrated.