一种评估风电场电压闪变的实用方法

为解决风电场并网引起的并网点电压闪变评估问题,将风电机组出力曲线拟合和电网络理论应用到其中.风电场根据电网络理论可以等效为一台风力发电机及其相关阻抗.在分析相关文献的基础上,探讨了风电场网络的建模和等效问题,从理论上证明了容量较小的风电场不会引起较大的电压闪变；详细地描述了IEC61400-21风电场电能质量评估标准,该标准包括在运行时和切换操作时对电压闪变的评估；同时简略描述了相关国家标准中对电压闪变限值的要求；通过使用IEC61400-21和IEC61000-4-15对之开展了分析,提出了一种评估风电场电压闪变的实用方法.最后,以某风电场为例,使用该方法进行了电能质量评估；并基于国家标准,对评估值作出了评价.研究结果表明,该风场运行时短时电压闪变值只有0.009 185,切换操作时产生的短时电压闪变值更小,远远低于限值0.8.

Practical method for evaluation of voltage flicker from wind farms

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.