Application of solid-state phase shifter to stabilization of system frequency in an interconnected power system

Abstract

Nowadays, the electric power industry is in transition to a deregulated market. Under this circumstance, any power system controls such as load frequency control (LFC) and voltage control will serve as an ancillary service, and the power system configuration will be changed by the proliferation of independent power producers (IPPs). In this paper, a control method using a solid-state phase shifter to provide active control facility of system frequency is proposed. In the LFC, the interconnections among some areas are the inputs of disturbances, and therefore, it is important to suppress the disturbances by the coordination of governor systems. In contrast, tie-line power flow control by phase shifters located between two areas makes it possible to stabilize the system frequency oscillations positively through interconnection, which is also expected to provide a new ancillary service for future power systems. This paper proposes a control design method of phase shifters for stabilization of frequency oscillations based on an elementary two-area system and an elementary three-area loop system, which can be extended to the design in a general multiarea system by applying a system reduction method. The design idea is based on stabilization of an interarea oscillation mode between interconnected areas. Numerical results demonstrate the significant effect of the proposed control on the stabilization of frequency oscillations in interconnected power systems. © 2000 Scripta Technica, Electr Eng Jpn, 132(3): 19–29, 2000