Parameters determination of UPQC based on different compensation strategies

Based on most common main circuit structure of left series-right shunt of unified power quality conditioner(UPQC),steady-state equivalent circuit and fundament component phasor representation un-der different compensation strategies are established to detemined the parameters of UPQC.The compara-tive analysis of energy flow relationship with different compensation strategies was shown and the capacity calculation formulas of series and parallel sides were given.According to the energy flow relationship,the selected principle of main circuit capacity was determined.The reason of DC voltage fluctuation was ana-lyzed and the selected method of DC capacitor was proposed to provide theoretical basis for the selection.The results show that the load voltage is not affected by grid voltage drop.Grid current THD value re-duces from 25.1%,25.8%,26.6% to 4.2%,4.8%,5.2% 。