Research of Direct Power Control for PWM Rectifier under Unbalanced Grid Voltage

The phenomenon of unbalanced grid voltage would add a lot of harmonics to AC current and DC voltage of Voltage Source Rectifier (VSR), and reduce the power factor or even damage the rectifier unit. In the paper, a developed direct power control (DPC) strategy for PWM rectifier under unbalanced grid voltage conditions is proposed to solve the problems. First of all, the instantaneous power could be calculated by the positive and negative sequence voltage and current. The comparison value between reference values and calculated values of power are regulated to build the output voltage space vector in order to use SVPWM. This strategy can make the output voltage desirable and improve the power factor and system performance. At last, the results of the simulation verify that this strategy is correct and feasible.