Compensation of Voltage Sags with Phase-Jumps through DVR with Minimum VA Rating Using PSO based ANFIS Controller

Dynamic Voltage Restorer

A DVR is a power electronic device, connected in series to the feeder, to protect the loads from typical voltage problems in distribution system. The schematic diagram of a series compensated distribution system is shown in Figure 1. In Figure 1, the source voltage is represented by v_S. The terms L_S and R_S represent feeder inductance and resistance. The terminal voltage and load voltage are represented by v_t and v_l, respectively. The DVR is realized by a voltage source inverter with DC capacitor voltage V_dc and power electronic switches S₁, S₂, S₃, S₄. The term L_ts represents the leakage inductance of the injection transformer and C_f represents the capacitance of the capacitor filter. The operating principle of the DVR is to inject a voltage (v_DVR) of required magnitude and phase to compensate sag/swell and distortion in the terminal voltage (v_t) and provide a balanced sinusoidal voltage (v_l) at the load. The reference DVR voltage to be injected (v_DVR) is realized by switching S₁, S₂, S₃, S₄ through hysteresis control (Woodley, Morgan, & Sundaram, 1999).

Figure 1.

Per phase representation of series compensated distribution system