Phase Error Analysis of Phase-locked Loop under Voltage Perturbation

In recent years, with the increasing capacity of renewable energy, the accurate extraction of grid phase is important to ensure the stable operation for power electronic devices with Phase-locked Loop (PLL). Voltage perturbation imposed to the grid, phase error will be induced in the output of PLL affects the current of power electronic devices. In this paper, the phase error is analysed by applying three approaches, i.e. in time domain, by using harmonic linearization, and based on linearized PLL model separately. The transfer functions between the phase error and voltage perturbation are derived in the three approaches. The three transfer functions are compared, and the result indicates that these transfer functions are the same with the frequency shift and phase shift considered. Experiment based on the sweep frequency test method validates the analysis of the phase error under voltage perturbation.