Comparison of two methods for evaluating the effects of maintenance on component and system reliability

Two recently proposed methods for evaluating the effects of various maintenance policies on the reliability and operating costs of electric power systems are compared. Both programs, the one developed in Canada and the other in Sweden, first generate a priority list of components whose failures have the highest effect on system reliability, then examine the failure rates of the components on the top of the list when various maintenance policies are applied. Finally, reliability indices for the whole system are computed with the critical components represented by the failure rates corresponding to the various policies. This way, maintenance policies can be selected either to achieve the highest system reliability or the lowest operating costs. The approach is illustrated in a numerical example where both the similarities of, and the differences between, the two methods can be recognized. Comments are made on the reasons for the differences