Abstract: The MonteCarlo method has characteristics of flexibility and effectiveness and is widely used in reliability assessment of the power system. However, in order to enhance the calculation accuracy, the calculation time will increase greatly, and this restricts its application scope. The influences of various components in the system on the system reliability were evaluated. On this basis, a simple assessment algorithm was established. By purposive sampling, the components, which threaten the system reliability, were identified. The experiment and the analysis show that the algorithm has higher convergence speed; it can reduce the calculation time and enhance the calculation accuracy in same time. Then the algorithm is more universal.

Key words: large power system, reliability assessment, variance control technique, Monte-Carlo method, simulation optimization, method with splitting optimal multiplier