Research of Application of Fuzzy PID Control Strategy in DVR

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.