适应于双馈风电场送出线不对称故障的时域距离保护

Time domain distance protection for asymmetric faults of an outgoing line in doubly-fed wind farms

目前,双馈风电场不对称短路电流特性对风电场送出线距离保护的影响以及相关优化策略的研究,主要是在计及Crowbar保护动作的基础上进行的,少有研究系统发生不对称故障后计及RSC控制的短路电流特性对传统距离保护的影响。基于此,分析了系统发生不对称接地故障后,计及Crowbar保护和RSC控制两种运行工况下的短路电流特性,解析推导了这两种运行工况下离散傅里叶算法提取基频分量产生的误差表达式。在此基础上分析双馈风机短路电流特性对传统距离保护的影响,从而提出了不受风电场短路电流特性影响的具有抗过渡电阻能力的时域距离保护。最后在Matlab/Simulink平台上建立DFIG电磁暂态仿真模型,仿真分析了风电场送出线发生单相经过渡电阻接地后,计及Crowbar保护动作和RSC控制两种运行工况下传统距离保护和时域距离保护的动作特性。

At present,research on the influence of asymmetric short-circuit current characteristics of a DFIG wind farm on the distance protection of the outgoing line of the farm and the related optimization strategy are mainly based on the action of crowbar protection.There are few studies on the influence of short-circuit current characteristics of RSC control on traditional distance protection after an asymmetric fault occurs.The short-circuit current characteristics of crowbar protection and RSC control under two operating conditions are analyzed,and the error expression of the fundamental frequency component extracted by discrete Fourier algorithm under these two operating conditions is analyzed.The influence of short-circuit current characteristics of the DFIG on traditional distance protection is analyzed.Time domain distance protection with transient resistance is not affected by short-circuit current characteristics of wind farms.Finally,a DFIG electromagnetic transient simulation model is established on the MATLAB/Simulink platform,and the operational characteristics of traditional distance protection and the time-domain distance protection under two operating conditions,including crowbar protection action and RSC control,are simulated and analyzed after single-phase grounding of the wind farm outgoing line through transition resistance.