配电网中性点经小电阻接地系统改造方案研究

Study on the Reconstruction Scheme of Distribution Grid Neutral-Point Grounding System Through Small Resistance

小电阻接地方式可有效降低过电压和提高故障选线率,但在小电阻改造过渡期间存在并列转供电等问题。通过对一次接线方式进行分析,在小电阻接地变高压侧与主变低压侧间加装专用开关。对改造后的运行方式进行继电保护分析并提出相应的二次应对措施及过渡方案,实际应用案例表明,新方案有效提高了配电网小电阻接地改造期间的供电可靠性。

Small resistance grounding method can effectively reduce overvoltage and improve fault line selection rate,but there are some problems during the transition of small resistance transformation,such as parallel to power supply.Through the analysis of the primary wiring mode,a special switch is installed between the high voltage side of the small resistance grounding transformer and the low voltage side of the main transformer.Relay protection analysis is carried out on the operation mode after transformation and corresponding secondary countermeasures and transition schemes are put forward,and the practical application shows that the new scheme can effectively improve the reliability of power supply during the transformation of small resistance grounding in distribution network.