基于广域零序分布电压特征的小电流接地选线方法

A Method for Single-Line-to-Ground Fault Feeder Selection Based on the Characteristic of Wide Area Zero Sequence Voltage

传统小电流接地选线装置准确性易受系统不平衡电流、电流互感器一致性差异等因素影响。为此提出一种基于广域零序电压分布特征的单相接地故障选线新方法。利用电网的分布参数模型分析得到了配电网发生单相接地故障后不同线路零序电流的分布特征,并据此归纳、推导了配电网不同接地方式下的零序电压的沿线分布特征。由于故障线路与健全线路间零序电压的分布特征存在差异,文章构造了故障测度因子作为选线判据,并通过引入能够描述故障与健全线路差异度、健全线路相似度的相对故障测度矩阵和投票机制来减小故障距离、过渡电阻和脱谐度对选线结果的影响,从而提高选线结果的可靠性。利用PSCAD建立了符合配电网线路分布参数特征仿真模型,仿真计算结果表明,在不同的接地方式、故障距离、过渡电阻和较小的脱谐度情况下,该方法均能正确选出故障线路。

Traditional grounding line selection device is prone to be affected by unbalanced current and difference of current transformer parameters, leading to inaccurate result. To solve the problem, this paper proposed a novel fault line selection method based on zero sequence voltage. In this paper, zero sequence current characteristics of healthy and fault lines were obtained with distributed parameter model, and then characteristics of zero sequence voltage were obtained. Because of difference of fault and healthy lines in zero sequence voltage characteristics, matrix describing the same characteristics of healthy lines and the difference between fault and healthy lines and voting mechanism were used to reduce impact on fault line selection. PSCAD simulation results show that, this method is effective in different grounding modes, fault distances, transition resistances under small off-tuning degree. In addition, necessary zero sequence voltage can be obtained with WAMS, making the method easy to implement.