Resynchronization Analysis and Improvement of Grid-Connected VSCs During Grid Faults

Grid codes stipulate that grid-connected voltage source converter (VSC) interfaced generation units should possess fault ride-through capability during grid faults. Resynchronization with the postfault is crucial for this purpose. However, it not always easy VSCs connected to a high-impedance weak achieve resynchronization severe This article studies loss of synchronism (LOS) A nonlinear model describing dynamics phase-locked loop (PLL) developed, and modified equal area criterion utilized identify factor affecting resynchronization. The findings show PLL’s integral regulator unfavorable since probably causes system operating point enter negative damping zones even reverse regulation zones, consequently resulting in LOS. variable structure PLL method great simplicity proposed improve capability. removes faults eliminate its effect. Experimental simulation comparisons existing methods verify performance method.