Abstract
This paper describes a control method and system configuration of UPFC(Unified Power Flow Controller). UPFC is one of the promising power electronics equipments because it is an extremely flexible power controller capable of controlling all of the transmission line valiables(voltage, impedance and voltage phase angle). Due to the control flexibility, however, it is important to select a proper contol scheme corresponding to the purpose.
Under the reserch project for the reinforcement technology of electric power interconnection, a miniature model of UPFC for the real time analog simulator was developed. Series side of UPFC has three control modes (perpendicular voltage control, impedance control and voltage angle control). It is used for power flow control and/or power system stabilizing control. Shunt side is used for voltage control or reactive power control in addition to compensating the power required from series side. Various tests were performed to compare control modes and the perpendicular voltage control is proposed as the simplest and most practical method because the capacity of the shunt compensator is minimized and power flow control sensitivity is maintained over a wide range of angle.
