In view of the situation that no zero sequence current compensation is achieved by three-phase three-wire SVG（static var generator）in low voltage system

a kind of main circuit of four-bridge inverter SVG is designed

the current containing zero sequence component is detected by the improved reactive power current detection method

the SVC is controlled by the use of predictive current control strategy so to compensate effectively unbalance zero sequence current in the system. It is shown by the two level four-bridge SVG simulation and analysis which is set up at Simulink that the control method in the paper can perform reactive compensation effectively to the unbalance system of load.