Research of Off-grid Energy Storage Converter Based on Repetitive Control and PI Control

Energy storage converters run in micro-grid off-grid mode as the main power supply, and the quality of output waveform of such converters is one of the most important aspects for evaluation of its performance. The mathematical model of off-grid energy storage converter in three-phase static coordinate system has been established in this paper. The PI controller is used to improve the system dynamic performance and repetitive controller the static follow-up performance by using its trait of zero steady-error to periodic disturbance. Based on the internal model principle, in this paper compound control method is present which makes PI control and repetitive control combination for off-grid energy storage converter. Finally, a 50kVA micro grid test platform is set up, the experiment verify the scheme can work well, fast response, highly accurate steady output and less distorted waveform is gained.