10 kV大容量配电变压器差动保护配置应用研究

差动保护常作为变电站中大型变压器的主保护,在10 kV配电变压器上应用案例较少。介绍了一起10 kV配电室中2 500 kVA大容量配电变压器的接地故障起火案例,分析了故障原因。利用仿真软件,对可能出现的低压侧短路故障进行仿真,探讨了不同情况下的中低压保护动作情况。结合故障分析,对该案例中10 kV配电变压器差动保护配置的必要性进行研究,结果显示配变差动保护可有效解决中低压保护整定配合定值与时延级差难以配合的问题,可灵敏监测低压侧接地故障下的保护“盲区”数据。针对性地设计了中低压二次系统改造方案,以差动保护配置为核心,完成智能综合监控系统建设。应用效果显示差动保护满足10 kV大容量配变极高的供电可靠性要求。

Differential protection configuration of a 10 kV large capacity distribution transformer

ifferential protection is often used as the main protection of large transformers in substations, but there are few cases where it is applied to 10 kV distribution transformers. A fire in a 2500 kVA large-capacity distribution transformer in a 10 kV distribution room is introduced, and the cause of the fault is analyzed. A possible short-circuit fault in the low voltage side is simulated by the software, and the action of the low and medium voltage protection under different conditions is discussed. Combined with the fault analysis results, the need for differential protection of a 10 kV distribution transformer in this case is studied. The results show that the differential protection can effectively solve the problem of the difficulty of the coordination between the setting value and the time delay range of the medium-low voltage protection, and at the same time, it can sensitively monitor the protection "blind zone" data under the grounding fault of the low-voltage side. The transformation scheme of the secondary system is designed, and the construction of an intelligent integrated monitoring system is completed with differential protection configuration as the core. The results show that differential protection can meet the extremely high supply reliability requirements of a 10 kV large-capacity distribution transformer. This work is supported by the National Natural Science Foundation of China (No. 51777082).