The capacity of renewable energy power generation has been soaring with the development of global energy internet

which results in the growing of the difference between the maximum and minimum power requirements from a power grid.To solve this problem

coal-fired power plants have to undertake more peak shaving task which means they will stay in low-load operation state for a long period of time.A set of index system for evaluating the capability of coal-fired power units in low-load operation was established

considering its feasibility.By fuzzy comprehensive evaluation(FCE)method

the indexes of safety

energy-consumption and environment protection were evaluated

and the weight of each index obtained by the analytic hierarchy process(AHP)was ascertained.Moreover

seven different types of coal-fired power units were selected as the examples to carry out comprehensive evaluation for the value of indexes

on the basis of the K-means K-means clustering algorithm.According to the evaluation results

several suggestions for the optimization of different level units and the dispatching of the power gird were proposed.