An Energy-Saving Series Compensation Strategy Subject to Injected Voltage and Input-Power Limits

A new series compensation technique is proposed as part of a power-quality control center scheme. The series compensator (SC) is fed from an active source but the allowable amount of its instantaneous output-power change is constrained. The technique also takes into account the apparent power rating of the SC. Under a voltage sag/swell and through the proposed injection voltage-control strategy, the technique allows the compensation to be carried out at a minimum energy level and, thus, offers an increased ridethrough range for the compensated load under voltage sag/swell. Furthermore, the load ridethrough ability is shown to be insensitive to the voltage phase jump introduced during the disturbance. Analytical expressions pertaining to the injected voltage magnitude and phase angle are derived and from which the extent of the sag/swell that can be ridden through is readily determined. Simulation results show the efficacy of the proposed method through the use of a modestly sized SC.