The power quality problem of active and reactive power is caused by the negative sequence and zero sequence components as well as harmonics in the three-phase unbalanced low voltage grid. Compensation optimization control is performed by the DSTATCOM with good dynamic performance and small harmonic contents. Zero sequence components are separated by way of coordinate transformation method for individual compensation control. Two individually adjusted parameters is set based on double frequency fluctuation of power caused by negative sequence current in the fundamental wave so calculate the reference current at different control objective

deduce unified control expression

optimize individual parameter by way of particle swarm optimization and

at the same time

suppress active and reactive power fluctuation. The proportional resonant controller is introduced to control AC component of vector current so to complicate dq coordinate transform calculation and simplify the control strategy when the same result as the PI adjustment is reached. The simulation verification is given. It is shown by the result that in case of three-phase unbalance and when the reactive power limit is within 10%

the active fluctuation is weaken correspondingly by 16% and the feasibility and effectiveness and the control method proposed in this paper is verified.