小电阻接地系统单相接地故障地电位分布与人身安全性研究

Research on Ground Potential Distribution and Human Safety of Single Phase Short Circuit in Low Resistance Grounding System

在小电阻接地系统中,若线路发生单相接地故障将在故障点产生较大电流,数百安的接地电流会引起地电位超过安全允许值。对某市10kV小电阻接地系统发生单相接地短路后会造成地点位升高进行了定量分析。首先,对该线路在单相接地短路时故障短路电流进行了模拟理论计算和MATLAB仿真,得到故障发生后将产生超过安全允许的电流值。其次,运用有限元分析软件ANSYS分析了杆塔旁土壤地电位分布,并分析其跨步电压对人身安全的影响。结果表明:故障发生后杆塔附近的跨步电压较大,远远超过人身安全允许值。最后,基于人身安全,提出了对重点地段输电线路杆塔附近的接地安全采取相应防护措施。

In a small resistance grounding system,if a single-phase ground fault occurs on a line,a large current will be generated at the fault point,hundreds of ampere grounding current will cause the ground potential to exceed the safety allowable value.The quantitative analysis of the increase of the position of the ground caused by the single-phase short-circuiting of the city’s 10kV small resistance grounding system is carried out.Firstly,the short circuit current of the power grid in the single-phase short-circuit is simulated and calculated by MATLAB,and the current value exceeding safety is generated after the fault occurs.Secondly,the finite element analysis software ANSYS was used to analyze the ground potential distribution of the tower,and the influence of the step voltage and contact voltage on personal safety was analyzed.The results show that the step voltage of the tower near the fault is larger than that of the allowable value of the personal safety.Finally,based on personal safety,it is proposed to take appropriate protective measures to the grounding safety near the tower of the key transmission line.