Development of a 6.6 kV, 3,300 kVA Continuous Voltage Compensator (CVC) for Precise Voltage Regulation and Imbalanced Voltage Compensation in Distribution Lines

Continuous voltage compensator (CVC) has been recently developed to improve the power quality of distribution lines. A CVC comprises series and shunt static power converters with transformers, and its circuit topology is based on an unified power flow controller (UPFC). Features of theCVC include fast active power control and precise imbalanced voltage compensation using a series converter, which are not accomplished by the conventional step voltage regulator (SVR) and thyristor voltage regulator (TVR) based on tap-change control. Further, the CVC contributes to stabilizing distribution lines by supplying reactive power and negative sequence current from the shunt converter. The details of the control strategies of series and shunt converters are proposed, and the validity of proposed strategies is verified by fabricating a 200V, 20kVA scale-downCVC prototype. A 6.6kV, 3,300kVA full-scale CVC has been developed for comparing the voltage controllability with the conventional TVR and effectiveness of the CVC demonstrated in the field test.