Super capacitor energy storage systems are mainly used for power quality conditioning and dynamic microgrid regulation. In real power supply systems, harmonic voltage of power grids will increase with the widespread application of non-linear loads and sudden start-stop of large motors. As a result, problems such as waveform distortion, transient voltage drop, sudden voltage rise and 3-phase power asymmetry and so on will be caused.Owing to their high power density, quick charging/discharging and high conversion efficiency, supercapacitors are suitable for short-time power compensation of power grids.