中文摘要：

仿真分析发现双馈式风电机组低电压穿越期间的短路电流频率随故障前工况偏移工频。当变压器内部故障时，基于相量值的差动与制动电流将大范围波动，基于采样值的差动保护在某些采样点动作条件不满足，差动保护均无法准确稳定地动作。以某地区实际风电接入为例，在EMTDC平台上对风电场主变压器以及风电集群再升压变压器保护进行离线动作性能测试分析，结果表明，基于相量值及基于采样值的差动保护均无法保证快速动作，风电机组类型、运行工况、故障位置、故障类型及短路容量比是影响风电场送出变压器保护正确动作的因素。

英文摘要：

Simulative analysis shows that the short circuit current frequency of doubly-fed induction generator during low-voltage ride-through period deviates from the fundamental frequency according to the working conditions before the fault. When the transformer internal fault occurs,the differential action and braking currents of differential protection based on phasor values fluctuate widely and the action conditions of differential protection based on sample values are not satisfied at certain sampling points ,resulting in the incorrect and instable operations. With an actual regional wind farm as an example,the off-line action performance of the main transformer protection of wind farm and the step-up transformer protection of wind power group is tested and analyzed on EMTDC platform,which shows that,the fast action of differential protection based on either phasor or sample values can not be ensured and the factors influencing the accurate operation of protections for wind farm outgoing transformers are generator type ,operating condition, fault location,fauh type and short circuit capacity ratio.