| Summary: | In view of deficiency that DVR uses feed forward control method and PID control method to process voltage sag problem, the paper proposed a fuzzy PID control strategy. Implementing principle of the control strategy is as follows: when detection system of power grid voltage detects voltage of power supply appears sag, DVR is put into power grid; a standard sine signal is generated by standard signal model which is synchronous with power grid voltage, and the signal is compared with actual power grid voltage; then a compensated voltage set signal is obtained after fuzzy PID controller regulates the signal, and a PWM signal needed by inverter is produced by control link, which controls on-off of power switch of inverter through driving circuit; the filtered output voltage of inverter is injected into power grid through series transformer to counteract fluctuation of power grid voltage. The simulation result proved effectiveness of the control strategy.
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