In order to evaluate the benefit of renewable power generations, this paper proposes a comprehensive evaluation model which includes four indexes: reliability, economy, flexibility and environmental benefits. Firstly, the output of renewable generations is described by the Markov model. The Loss of Load Probability(LOLP) and Energy Expectation Not Served(EENS) are calculated. Secondly, the economy is presented by investment cost, operating cost and the cost of reserve capacity. Considering the uncertainties of load and renewable resource, the reserve cost is a tradeoff between reliability and economy. Thirdly, the flexibility represents the challenge on power balance caused by renewable resource. Fourthly, the environmental benefit is considered. After calculating all indexes, the entropy weight method is used to determine the weights among indexes so as to make a comprehensive evaluation of the benefit for the power system planning. Finally, a case study proves the validity of this model.

Comprehensive Evaluation,Reliability,Markov Model,Flexibility,Renewable Resource