光伏并网系统送出线路不对称故障的差动保护灵敏度研究

发布时间：2018-10-05 21:12

【摘要】：针对光伏并网发电系统的故障特性,分析了在并网送出线路发生不对称跌落时,比率制动特性差动保护在光伏逆变器有无无功补偿条件下的灵敏度。结果表明,在无功补偿状态下,光伏并网发电系统送出线部分的传统比率制动特性差动保护灵敏度下降。通过比较传统比率制动特性曲线的整定方式,不过原点的特性曲线在灵敏度的方面具有更大优势。在此基础上,考虑到不对称故障中零序电流受故障电阻和负荷电流影响小及低电压穿越(LVRT)期间以电网电压正序分量定向的逆变器控制策略,零序电流作为保护判据的传统比率制动式差动保护,由于不受无功补偿电流的影响且保护动作整定值较小,具有更高的灵敏度,作为光伏送出线路的保护效果更佳。通过Simulink搭建光伏并网发电系统仿真模型验证了这一结论。
[Abstract]:According to the fault characteristics of photovoltaic grid-connected generation system, the sensitivity of the differential protection of ratio braking characteristics under the condition of whether the photovoltaic inverter has reactive power compensation or not is analyzed when there is an asymmetric drop in the grid-connected transmission line. The results show that the sensitivity of the traditional ratio braking characteristic differential protection is decreased under the condition of reactive power compensation in the feed-line part of photovoltaic grid-connected generation system. By comparing the traditional setting method of the ratio braking characteristic curve, however, the characteristic curve of the origin has more advantages in sensitivity. On this basis, considering that zero sequence current in asymmetric faults is little affected by fault resistance and load current, and the inverter control strategy is oriented by the positive sequence component of grid voltage during the period of low voltage traversing through (LVRT). The traditional rate-braking differential protection with zero sequence current as the protection criterion is more sensitive because it is not affected by the reactive power compensation current and the setting value of the protection action is small. Therefore, the protection effect of the photovoltaic transmission line is better as the zero sequence current is used as the protection criterion. The simulation model of photovoltaic grid-connected generation system is built by Simulink to verify this conclusion.
【作者单位】：沈阳理工大学;
【分类号】：TM615;TM773

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