Electricity Supply Reliability: Evaluation of Improvement Solutions for Existing Electricity Networks

Abstract: Regulation of the electricity network business is continuously under development in many countries. This is a reaction of an increasingly electricity dependent society, which demands electricity supplies at acceptable quality levels and at reasonable tariffs. Thus, electric network companies are facing new requirements that change the conditions for exercising network activities. Generally, incentives are given to the network companies to maintain the present level of reliability in a cost-efficient way. In Norway, however, incentives are given to the network companies to plan, operate and maintain the networks in a socio-economically optimal way, taking into account the supply-interruption cost to the customers. Therefore, in Norway, electricity network companies strive to identify and implement the most cost-efficient reliability improvement projects, i.e., the projects that yield the greatest overall reduction in supply-interruption cost to the customers for the invested money. In this thesis, implementations of reliability improvement solutions on a test system have been evaluated from a socio-economical point of view. For each of the alternative solutions implemented on the test system, the average annual supply-interruption cost to the customers supplied from the test system has been estimated. Furthermore, the maximum annual capital cost associated with the implementation of each solution has been estimated. Then, a reliability improvement solution is considered justified socioeconomically if the capital cost associated with its implementation is less than the resulting reduction in the interruption cost to the customers. The general conclusion from this thesis work is that the supply-interruption cost to the customers supplied from a test system can be reduced significantly by implementing reliability improvement solutions that are justified socioeconomically. Even if the uncertainty of the input data is taken into account, it is obvious from the results that the interruption cost to the test system customers can be reduced to at least half the initial value.