Stability Analysis of Three-phase LCL-type Grid-connected Converters for PLL Parameter Design

Abstract

The three-phase LCL-type converters play a significant role in power systems; however, the unreasonable parameter design of SRF-PLL can cause the instability of the converter. In this paper, the impedance model of a three-phase LCL-type grid-connected VSC with SRF-PLL is presented, and the stability criterion of the converter is analyzed. Then, the SRF-PLL parameter design method of the three-phase LCL-type grid-connected voltage-source converter by analyzing the stability of the converter is proposed. The simulation platform is built in MATLAB/SIMULINK to verify the theoretical analysis. Simulation results shows that the proposed PLL parameter design method can help complete design of PLL effectively and enable converter to work stably.