A novel hybrid coordinates multiple decoupled phase‐locked loop under nonideal grid conditions

Abstract

AbstractA novel hybrid coordinates multiple decoupled phase‐locked loop (HCMD‐PLL) is presented to improve the performance of the PLL under nonideal grid conditions. Based on the Clark transform and the first‐order low‐pass filter, the complex coefficient filter is derived to analyze phase‐locked loop. It is different from the phase‐locked loop with a complex coefficient filter. On this basis, the multiple‐complex‐coefficient band‐pass filter of HCMD‐PLL is derived, and the equivalent transfer function of the decoupling of the fundamental positive sequence, negative sequence and harmonic components is obtained, and the magnitude and phase frequency responses are analyzed. The fundamental positive sequence component is extracted without phase shift and amplitude attenuation under the nonideal grid conditions, eliminating the effect of specific‐order harmonics components because the amplitude is attenuated to zero. And the specific‐order harmonic component can also be extracted precisely. The interaction from the various specific components is eliminated. The stability of the system is analyzed by the pole distribution of the closed‐loop system. The stationary αβ coordinate system for PLL is adopted to suppress the change of the grid voltage. Simulation and experimental results verify the effectiveness of the HCMD‐PLL. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.