Abstract
SYNCHRONOUS STABILITY ANALYSIS OF PHASE-LOCKED SYSTEMS FOR MULTI-VOLTAGE SOURCE CONVERTERS BASED ON LYAPUNOV'S SECOND THEOREM
Qiuting Tan*
ABSTRACT
In the case of severe voltage plunge, the grid-connected voltage source converter (VSC) system based on phase-locked loop (PLL) synchronization is susceptible to transient instability and tripping from the grid. In this paper, the grid-connected systems of multi-paralleled VSCs are analyzed qualitatively by Lyapunov's second theorem method, and the corresponding stability criteria are constructed for the analysis of grid synchronous stability (GSS) of the multi-paralleled VSCs system. Firstly, the large signal model of the multi-paralleled VSCs system based on the PLL is constructed. Then, the GSS is quantitatively analyzed based on Lyapunov's second theorem method. At the same time, the influence of different working conditions (short-circuit ratio, voltage drop degree, and current injection amount) on the GSS of the multi-VSC system is revealed. Finally, the VSC-Infinite bus system is used as the test system to verify the accuracy of theoretical analysis in the Matlab/Simulink simulation platform. Theoretical analysis and simulation results show that the proposed method can provide reliable GSS evaluation.
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