Relay protection condition assessment based on variable weight fuzzy synthetic evaluation

Fuzzy synthetic evaluation (FSE) is a common method for relay protection condition assessment, but its constant weights are unable to objectively reflect the impact of the deviation of assessment parameters and the condition assessment result is not satisfied. Aiming at the deficiency, a variable weight fuzzy synthetic evaluation (VWFSE) method is proposed. Variable weight is the main feature of VWFSE. This paper firstly analyzes the deficiency of FSE. Then, aiming at the deficiency, VWFSE is proposed. The method calculates the variable weights combining with fuzzy analytic hierarchy process (FAHP) and variable weight theory. The weights can automatically vary to follow the change of assessment parameters. Fuzzy theory is used to build the membership functions of each assessment parameter and the fuzzy judgment result vector is calculated to evaluate the comprehensive condition of the relay protection system. Compared with FSE, the condition assessment result of VWFSE is more close to the actual condition of relay protections. Finally, a practical example proves the effectiveness of the method.