Assessment of Reliability Worth

The function of a modern electric supply system is to provide electric power to customers at reasonable cost and acceptable levels of reliability. Reliability consists of both adequacy and security of supply; hence supply interruptions, regardless of the cause, constitute a reduction in reliability. Acceptable levels of reliability are normally assigned on the basis of experience with little or no attempt to directly relate target levels to economic or socioeconomic parameters. Increases in energy costs, construction costs and interest rates, the recognition of conservation and environmental concerns and the impacts of government and public groups have resulted in the need for a more rational and consistent approach to determining acceptable reliability levels. A major aspect of this approach is the attempt to assess the worth of power system reliability in order to be able to compare it with the costs of obtaining that reliability [1].