10kV小电阻接地系统单相接地故障分析及应对措施

Analysis of Single Phase Ground Fault in 10 kV Low-resistance Grounding System and Countermeasures

随着我国配电网自动化水平不断提高,配电网故障的快速预防和处理技术应用变得越来越普遍。由于我国的配电网覆盖面广,所以配电网故障率也相应较高,其中80%以上都为单相接地故障。随着城市电缆配网规模的日益扩大,中性点经小电阻接地方式因其可以有效抑制过电压而变得越来越普遍。但在这种接地方式下,金属性接地短路可能将产生较大的零序电流,从而会导致断路器跳闸,这严重影响了电力系统的安全稳定运行。为研究小电阻接地系统电缆线路发生单相金属性接地短路的基本规律,介绍了某供电企业电缆小电阻接地方式下的两起金属性单相接地故障,分析了故障发生后的处理过程和可能导致故障产生的原因,最后给出预防性建议,从而加强了配电网的稳定性。

With the continuous improvement of distribution network automation level in China,the rapid prevention and treatment technology of distribution network fault becomes more and more common.With the increasing scale of urban cable distribution network,neutral point grounded by low resistance becomes more and more common,which can effectively suppress over-voltage.But in this kind of grounding mode,the short-circuit of metal grounding may produce large zero sequence current,which will lead to the tripping of the circuit breaker and seriously affects the safe and stable operation of the power system.In order to study the basic principle of single-phase metallic ground short circuit in the cable line of low-resistance grounding system,this paper introduces two metallic single-phase grounding faults in a power supply company under the mode of low-resistance grounding,analyzes the processing process after the fault and the possible causes of the fault,and finally gives preventive suggestions,so as to strengthen the stability of the distribution network.