In order to further accelerate the convergence speed of Monte Carlo method

an importance-control method (ICM) for power system reliability evaluation is proposed by referring to the importance sampling method and variable control method. ICM makes use of component importance analysis to identify the components with a greater influence on system reliability. Based on the failure effect of the above important components and the characteristics of system state analysis

ICM can construct importance control variables that meet the requirements for calculation. With the importance control variables constructed

the reconfiguration of system important state function can be realized. It is shown by theoretical inference from the method that it is capable of effectively reducing the sampling variance without increasing the sampling calculation workload per time. The accuracy and efficiency of ICM is verified using an IEEE-RTS79 system and the modified system. This work is supported by National Key Technology R&D Program of China (No. 2013BAA01B02).