Aiming at the problem of three-bridge-arm double capacitive SVG compensation accuracy in three-phase four-wire system

its model is analysed. A self adaptive enhanced phase-lock-loop（EPLL）is suggested in which the phase follow is not affected by the unbalance voltage and is of good Robust stability and high accuracy. In order to overcome the shortcomings of resonance peak

high power loss and lower filtering efficiency in traditional LCL filter

a LCL filtering method with RC in series is designed to be applied in the three-bridge-arm double capacitive SVG in three-phase four-wire system. Based on such model

the system transfer function is built up and then the filtering parameters are designed. The simulation and experimental results show that this model can effectively restrain the harmonic with switch frequency and with good restrain effects to high frequency ripples. EPLL can guarantee the response speed and increase the current following accuracy.