In this paper,based on the principle of static var generator,the positive and negative components of phase are first phase locked respectively combined with symmetrical component method in the d-q coordinate system,and then the active current and reactive value of load current in the positive and negative sequence are calculated.So we can avoid the phase-locked angle error caused by asymmetrical three-phase voltages through traditional phase locked loop technology.Then the DC signal is extracted using integral filtering method instead of the traditional low-pass filter.When the system of three-phase is asymmetry,each current of phase is simplified then processed by integral filter,which reduces the inherent delay in the traditional system.Finally,an improved reactive power compensation system simulation model is set up in the MATLAB environment.From a series of simulations of fundamental current extraction and reactive power compensation,we can see that the improved SVG can realize the real-time detection of reactive current:the system detection delay is less than 0.02 s and reduced by 60% compared with the traditional detection model.The power factor of the original system can be increased to more than 95% after adding the static var compensation system in a power cycle.