基于正序分量的多端输电线路精确故障定位研究

3 算例仿真

为验证本文所提出的算法正确性,本文利用PSCAD软件进行仿真分析,采用全波傅里叶滤波,窗口时间20 ms,采样频率2400 Hz,每周波采48个点。

3.1 三端线路故障定位仿真验证

以图5所示线路中故障发生在L1支路,故障类型为A相短路接地,过渡电阻10 Ω,故障点距离分支接点O处30 km的事故为例,并选取L1为基准支路,L2为对照支路,其余参数见表1。此时依据长线方程计算所得正序基波电压沿上述两支路分布情况如图8所示,其中粗虚线、粗实线分别为算法第一、二步中电压沿线路的分布情况,细实线为辅助延长线,UPFCUPFC指正序基波电压。可见仿真结果所绘图8与图3中所示原理完全一致。

表1 三端线路参数

图8 线路沿线正序基波电压

由式(24)可知,仿真计算所得判别矩阵中,L1支路所在行均有解,列均无解,符合算法原理中所述特征,有效识别出故障位于L1支路,并对所在行各有效值求解算术平均值,测得故障距离分接点O处29.990 34 km,测距误差仅为0.016%。故算法的正确性在仿真中得到证实。

进一步检验不同故障支路、故障类型和过渡电阻下算法的有效性和高精度性,见表2。表3为多端线路参数。

3.2 多端线路故障定位仿真验证

表5表明当故障位于分支接点附近时,本文方法能够正确判别故障所在支路,同时保证较好的测距精度,故本算法对减小多端线路中测距死区的范围具有较好的效果。

本文方法中由于虚拟故障点必然比实际故障点更加远离分支接点,同时图4中所示原理在构造判别矩阵时已经考虑了互感器可能存在的测量误差,当二次侧设备测量误差较大时,本文方法会受一定影响,但是可以加强滤波,减小二次侧设备测

表2 三端线路在不同故障类型、过渡电阻下的仿真结果

表3 多端线路参数

量误差的影响。因此本文方法对于故障支路的判别较为准确,在测量过程中存在一定误差时,依然能够保持较好的测距精度。

表6列出了三端线路分支接点附近发生A相高阻接地故障时,本文方法与传统方法(以文献[20]为例)的比较结果,其中故障距离均指距离O点的长度,对比仿真均采用本文仿真时所用系统和参数,但因数据处理及其他因素影响,仿真和计算分析环境可能略有差异。从表6可以看出,传统方法在故障位于分支接点附近时失效,由于无法正确判别故障所在支路,进而无法正确实现故障测距,表6中以*号表示传统方法无法正确测距的情况。

4 结语

针对传统多端线路故障定位中普遍存在的测距死区问题,本文提出一种基于正序基波分量的多端线路精确故障定位算法。本算法基于正序基波分

表4 多端线路在不同故障类型、过渡电阻下的仿真结果

表5 多端线路分支接点附近不同故障类型、过渡 电阻下的仿真结果

量,采用双端方程有解和无解两种对立状态作为故障支路判别依据。大量仿真结果显示该算法不受故障类型、过渡阻抗、系统阻抗及系统运行方式等的影响,能保证较高的测距精度。此外本算法将多端

表6 三端线路中分支接点附近故障时测距结果对比

线路故障支路判别与故障测距融为一体,无需事先判别故障所在支路,同时对减小分支接点附近的测距死区范围也具有较好的效果。

作者简介：

刘瑞麟(1992),男,硕士研究生,研究方向为电力系统保护与控制、电网可视化等,E-mail：lrldyx16380@163.com;邰能灵(1972),男,教授,通信作者,博士生导师,研究方向为电力系统继电保护、高压直流输电、新能源等,E-mail：nltai@sjtu.edu.cn;

范春菊(1967),女,副教授,长期从事继电保护及电站综合自动化的研究及教学工作;

黄文焘(1989),男,博士,讲师,研究方向为电力系统保护与控制、微电网等;

刘志远(1992),女,硕士研究生,主要研究方向为电力系统稳定与控制。基金项目： 国家重点研发计划项目(2016YFB0900601); 国家自然科学基金项目(51377104);

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