Benders decomposition applied to OPF problems

One of the major challenges in the restructured electricity supply industry is the economic provision of system security both in the short and long terms. In order to limit the costs of security services purchased on the spot market (out-of-merit generation) as well as the exposure to the volatility of these costs, it may be necessary to have alternative means of managing the system security either through investment into various transmission facilities and/or through a portfolio of long term contracts with generators and customers. Several market mechanisms are now being considered, and some of them implemented, for the provision of various security related services, such as active and reactive reserve or transmission related reserves with generators, customers and transmission competing. However, a detailed investigation of the concept of a competitive provision of system security, its development and potential implementation is restricted by the lack of tools capable of simulating and facilitating such scenarios. In order to manage security costs efficiently long term costs (i.e. investment and purchase of appropriate contracts) must balance against short term operating costs over a wide range of system conditions. However, the conventional OFF based tools normally provide only `snap shot´ solutions, but not the ability to co-ordinate decisions over long time horizons. This paper discusses the management of system security in a competitive environment and describes Benders decomposition techniques as a promising candidate for the development of tools for competitive provision of system security