双馈风力发电机群短路电流实用计算方法

Practical Calculation Method of Short-Circuit Currents Contributed by Doubly-Fed Wind Turbine Cluster

近年来以双馈风电机组为主的风电场大规模并网,对电网的安全稳定运行构成了很大的挑战。而具备了低电压穿越能力的双馈风电机组的故障特性发生了改变,同时当多台双馈风电机组同时运行时,其不同的组成型式和繁多的集电线路使得整个拓扑结构变得复杂,导致短路电流的实用计算变得困难,且难以保证其准确性。针对上述问题,在研究建立含撬棒（Crowbar）保护的双馈风电机组短路电流实用计算模型的基础上,推导了双馈风电机组的等效阻抗模型,同时计及集电线路的转移阻抗,进一步推导了风电机组不同组成型式下的短路电流计算等效阻抗模型,最终提出了双馈风力发电机群在其集电母线处短路时的短路电流实用计算方法。采用PSCAD/EMTDC建立多台双馈风电机组的精确仿真模型,验证了所提实用计算方法的准确性,并在此基础上与国家标准计算方法进行了比较分析。研究结果对风电机群的电气安全设计具有重要意义。

In recent years, large scale grid-connected wind power plants with doubly-fed wind generators（DFIGs） constitute a great challenge to safe and stable operation of power grid. Fault characteristics of DFIG with low-voltageride-through capability have changed, while type composition of wind turbines and electric circuits make whole topology more complex. These changes make it difficult to calculate short-circuit current and ensure calculation accuracy. To solve this problem, an equivalent DFIG impedance model is deduced in this paper on research of short-circuit current practical calculation of DFIG with crowbar protection. Then equivalent impedance model of short-circuit current considering transfer impedance of collection lines and wind turbines under different connection modes is proposed. Finally, a practical calculation method of short-circuit currents contributed by DFIG cluster is proposed. Accuracy of the proposed equivalent model is verified with PSCAD/EMTDC, and comparison with national standard calculation method is analyzed. The results are of great significance for electric safety design of wind turbine cluster.