The model and algorithm to evaluate bus system arrangements' reliability of pumped storage power stations are proposed based on the analysis of the pumped storage power stations’ characteristics. In the presented model

both generating electricity and pumping water states are considered. A generalized outage table which gives the probability and frequency distributions of the outage capacity due to the random failure of all the equipment in the switching station as well as the generator units can be obtained. So the different operation modes can be simulated strictly. Furthermore

the reliability indices are converted into economic indices through the loss of the un-generated energy. A software REBUSⅢ for evaluating the bus system arrangement's reliability of the pumped storage power stations is developed and has been applied successfully in several practical pumped storage power stations.