Costing of transmission outages

The operation of a grid system requires equipment to be taken out of service to complete both maintenance and construction work. When a transmission circuit is taken out of service, the power system´s ability to transmit power, the transfer capability, is reduced. If this lower transmission capacity cannot sustain the flows resulting from operating the generation in merit order, a transmission constraint results and the outage impacts on the economic operation of the power system. Under these circumstances, it is necessary to operate plant “out of merit” in order to reduce the flows on the transmission system. When it is necessary to constrain the output from a generator despatched by NGC, compensation payments are made by the electricity pool. The detailed payments are subject to a very complex formula. Here, the author examines the costing of such utility transmission outages