Practical method for evaluation of voltage flicker from wind farms

YOU Pei-yu， XV Zheng
（School of Electrical Engineering， Zhejiang University， Hangzhou 310027， China）

Abstract： In order to solve the problems of evaluating voltage flicker from wind farms，fitting the active power output curve of the wind turbines and the electric network theory were investigated. According to the electric network theory，an equivalent model of a wind farm could be founded to substitute the wind farm with impedances and a simplified wind turbine. After analyzing several references，modeling and equalizing of the network of a wind farm were discussed. It was proved theoretically that giant flicker could not be caused by wind farms with a relatively tiny capacity. IEC 61400-21 criteria to evaluate power quality problem triggered by wind farms was also mentioned in detail. The standard included the evaluation of voltage flicker during switching mode and the normal operation mode. Relevant national standard for voltage flicker was also reviewed briefly. After the analysis with IEC 61400-21 and IEC 61000-4-15，a feasible and portable method to evaluate voltage flicker from wind farms was presented. Then，the fundamental condition of one wind farm，was portrayed and studied for the target. According to the national standard，the outcomes were commented. The experimental results show that during normal operation the short-time flicker is 0.009 185. By transients the levels tended to be lower，which are far below the limit of 0.8.
Key words： wind farm； voltage flicker evaluation； IEC61400-21