Using a FACTS device controlled by a decentralised control law to damp the transient frequency deviation in a deregulated electric power system

Abstract

In a deregulated electric power system, energy exchanges may exist depending on load following contracts between agents belonging to different areas. As direct consequence of this, the need may arise for new control apparatus and new effective control laws that favour power flows along specific corridors. In such a context, in the paper a great interest has been devoted to the use of FACTS devices to improve the load–frequency control of the system. Indeed, FACTS devices can regulate the power flow in a transmission line, also improving both transient and dynamic stability. This paper then proposes a method based on the application of the overlapping decomposition technique, to design a decentralised control law of a SSSC device. The principal idea is so to decompose a multi-area power system into two decoupled subsystems. The SSSC represents the former subsystem, while the latter is made up of the whole multi-area power system with inside the conventional controllers. As a consequence, each subsystem may be considered as independent. Greater simplicity hence results in designing decentralised optimal control laws for each of them with respect to a defined performance index. In the paper, in order to verify the validity of the proposed method, some numerical tests are carried out.