New Probabilistic Approach Taking into Account Reliability and Operation Security in EHV Power System Planning at EDF

In the planning studies on EHV systems at Electricité de France, reliability is measured by the expected energy which is not supplied by the generation - transmission system over a period of time. However, it is necessary to divide the unsupplied energy into two parts: - the static unsupplied energy corresponding to the loss of load that the operator may be led to accept as a preventive measure, in the unfavourable situations, to continue ensuring the operation security of the system; - the dynamic unsupplied energy corresponding to the loss of load after contingencies occurring in real time and not taken into account in the operation security rules. Probabilistic models, based on a Monte Carlo simulation method, have been developed to estimate the mathematical expectation of static unsupplied energy and the mathematical expectation of dynamic unsupplied energy. This last quantity allows to measure the operation security of the system.