부산대학교 도서관

Phase-locked loop (PLL) is widely used in voltage source converter (VSC) to synchronize with grid. This paper comprehensively analyzes the transient stability of the PLL-VSC and obtains the VSC’s instability characteristics similar to the synchronous generator. The instability of VSC is mainly caused by insufficient deceleration area and instability without equilibrium point. To improve the transient stability of VSC, a hybrid PLL is proposed. This method dynamically compensates the phase of the PLL to improve the transient stability performance of the system without obtaining the specific parameters of the grid line. The phase compensation of PLL creates new equilibrium points to solve the most problem of insufficient deceleration area or no equilibrium point. Time-domain simulations are given to verify the effectiveness of the theoretical analysis.