Research on the Impact and Optimization of the Active Current Recovery Rate of Distributed Photovoltaic Pulse Blocking Strategy on Grid Frequency and Voltage Stability

With the large-scale integration of Class B distributed photovoltaic power sources without fault-tolerant capabilities, the “pulse blocking-recovery” transient behavior during power grid faults has become a key factor affecting the frequency and voltage stability of the system. The recovery rate of active current after pulse blocking directly determines the speed of filling the active power deficit, but the mechanism of its impact on frequency and voltage stability has not been fully revealed. This paper first establishes a frequency response model for photovoltaic power grids with high penetration considering the pulse blocking control process, quantitatively analyzes the mechanism of the effect of the recovery rate of active current KIp on the minimum frequency value, recovery time, and overshoot quantity, and points out that a too-low KIp will lead to frequency instability, while an excessively high KIp will cause overshoot oscillations. On this basis, an optimization model with KIp as the only decision variable is established with the goal of minimizing the comprehensive cost of frequency response, and the adaptive grid search method is used to efficiently optimize. Finally, a simulation verification was conducted using an actual power grid case from a certain province in China. The simulation results show that the optimized recovery rate (KIp =1.50 p.u./s) is higher than the factory default value (0.10 p.u./s), raising the minimum frequency from 49.1 Hz to 49.82 Hz, shortening the recovery time from the unstable state to 0.60 s, and keeping the overshoot within 0.15 Hz. Compared with the quick recovery condition (3.00 p.u./s), the overshoot has decreased by 46.4% (from 0.28 Hz to 0.15 Hz), and the critical synchronization rate has increased by approximately 8.7% (from 61.8% to 67.2%). This provides a theoretical basis for the standardized management of grid-connected parameters for Class B distributed photovoltaic systems.