Impact of strength of fault current path on the operation of decoupled double synchronous reference frame – phase locked loop

Abstract

This paper studies the performance of decoupled double synchronous reference frame - phase locked loop (DDSRF-PLL) synchronizing method during grid fault. The study is carried out using Matlab/Simulink. The contribution of the paper is to reveal that if the DDSRF-PLL proposed in many papers is used, the control system of network side converter (NSC) may become unstable during a symmetrical grid fault. The instability problem appears only when certain tuning parameters of DDSRF-PLL are used and the fault current path is weak. Thus, the problem may not be easily detected. This paper emphasizes that it is mandatory to use PI-controller with integrator anti windup in the loop filter of DDSRF-PLL. In addition, the impact of angular frequency limitation range on the fault ride through performance is evaluated with comparative simulations.