电容电流反馈补偿系统的研究

Research on the Capacitive Current Compensation Feedback System

配电网系统的对地电容值与其运行方式有关,若在单相接地故障中改变了系统的运行方式,而消弧线圈的补偿不能随之变化,则会增大流过故障点的电流。为此介绍了高短路阻抗变压器式可控消弧线圈的基本结构和性能特点,在此基础上提出了电容电流反馈补偿的新方法。在配电网发生单相接地故障时,反馈补偿系统通过监测各条线路零序电流的变化,判断消弧线圈是否处于合适的补偿位置,通过反馈调节消弧线圈输出电流,避免了接地残流受系统运行方式变化的影响,保障了配电网的安全运行。动模试验的结果也验证了该方法的可行性。

In the resonant grounding distribution networks, instant arcs would be self-extinguished when there is an earth fault, which improves the dependability of power supply and the security of equipments and persons. At present, most of the distribution networks are equipped with arc suppressing coil （ASC） to reduce the influence of earth faults. In resonance systems, measuring the capacitive current of the distribution network has been done at normal operation, the measure result is the target of the output current of the ASC in single-earth grounding. The output current of the traditional ASC can＇t be adjusted in single-earth grounding. Because the capacitive current is related to the mode of network operation, when the mode varies in single-earth grounding, the residual current will be increased greatly for the distribution network using the traditional ASC. Based on the characteristic and structure of the controllable ASC of the transformer with high short circuit impedance, a new capacitive current compensation feedback system is proposed in this paper. In the system by monitoring the variation of the zero sequence current in each feeder, the output current of the ASC can be adjusted rightly, when there is a single-phase grounding in distribution networks. The purpose of the feedback adjustment is to minimize that residual current value, then the network configure has not any impact on the capacitive current compensation. The novel method is verified with the dynamic power system model.