FACTS devices in uplift control

Traditionally, security constrained economic dispatch is implemented by adding constraints to the plain economic dispatch-typically limits on line flows and nodal voltages for all credible post-disturbance configurations. However, advances in power electronics, and in particular the concept of FACTS are now challenging conventional approaches to system security operation, planning and overall economy of power systems. Based on FACTS devices, some part: of the security of the system can be achieved in post contingency mode, after an outage occurs. Such an economic dispatch, that incorporates the abilities of FACTS devices to assist in post-fault rearranging of transmission system power flows, allows the system to be operated with relaxed security most of the time. This results in reduction of the system operating costs without actually jeopardising the level of system security. In the context of the England and Wales electricity market, this paper demonstrates how FACTS devices can be used in uplift control. The paper proposes a method to the solution of the economic dispatch problem with an optimal balance between the level of security achieved in preventive and in corrective mode. The method is based on mathematical programming decomposition techniques that allow the iterative solution of a base-case economic dispatch for the intact system and separate contingency analysis with post-contingency corrective control by FACTS devices used to eliminate line/transformer overloads. A case study on a test system is presented and discussed.