A NOVEL DYNAMIC VOLTAGE RESTORER FOR UNBALANCED DISTRIBUTION SYSTEMS

Voltage unbalance of three phase ac distribution systems adversely affects power customers. This paper presents a novel dynamic voltage restorer, which is composed of a conventional three phase voltage source inverter and an emitter follower for unbalanced distribution systems. The negative effects of load caused by the negative sequence component of the supply voltage can be eliminated and the load voltage magnitude can be restored to referenced value by using the three phase voltage source inverter. The emitter follower is capable of eliminating the adverse effects of load caused by the zero sequence component of the supply voltage. The theoretical analysis and digital simulation verify the feasibility of this method.