基于故障暂态量时频联合分析的高压输电线路保护与故障定位方法研究

Ultra-high-speed and reliable relaying and accurate fault location of high voltage power network are important guarantees of transient stability and premises of intellectualization. Traditional relaying can hardly realize ultra-high-speed relaying, however, fault transient signals may solve the contradiction of relaying speed and reliability and increase fault location accuracy. The existing methods based on transient signals just make use of time domain or frequency domain information, with problems such as extraction and identification difficulties of traveling wave front and frequency aliasing. Transmission and distribution properties of fault transient signals along transmission lines from both the time domain and frequency domain sides simultaneously is firstly proposed in this project. The research of directional elements based on fusion of multiple frequency bands, which solve the extraction and identification difficulties of traveling wave front, is carried out using effective time-frequency analyzing methods. The research of features of natural frequencies at both ends of lines under different system impedances is made to solve extraction and identification difficulties of natural frequencies caused by frequency aliasing under complicated bus structures. Meanwhile, combined with methods of time-frequency mutual correction and time-frequency correlation analysis, the accurate time difference and wave speed of travelling wave is obtained to establish fault location system based on time-frequency correlation analysis. This project aims to propose new ultra-high-speed relaying and fault location methods based on fault transient signals, enhancing reliability of transient relaying and accuracy of fault location for high-voltage transmission lines.

超高速、高可靠的继电保护和精确可靠的故障定位是高压电网暂态稳定的重要保障与智能化的重要前提。传统保护难以实现超高速动作，故障暂态量的利用可望解决保护速动性与可靠性之间的矛盾，提高故障定位精度。现有基于暂态量的方法仅单一利用了时域或频域信息，存在行波波头提取与识别困难、频率混叠等问题，本课题首次同时从时域和频域两个角度考察故障暂态量在输电线路上的传播、分布特性，通过有效的时频联合分析方法，进行基于多频带特征融合的方向元件算法研究，解决波头难以提取与识别的问题；对不同系统阻抗下线路两端固有频率的特征进行研究，解决复杂母线下因频率混叠而导致的固有频率难以提取与识别的问题；同时，结合时频信息相互修正与时频相关分析方法，获取准确的行波传播时差及波速，建立基于时频联合分析的故障定位体系。课题旨在探讨发展利用故障暂态量的超高速保护与故障定位新原理，以提高高压输电线路暂态保护的可靠性和故障定位的准确性。

高压输电线路保护与故障定位承担着快速检测并清除线路故障的重大任务，是确保电网安全稳定运行的基础。传统的工频量保护为保证继电保护的可靠性，牺牲了一定的保护动作时间，为提高高压输电线路的继电保护性能，快速准确地查找线路故障位置，本项目深入挖掘输电线路故障暂态量的时域和频域信息，研究了基于故障暂态量时频联合分析的高压输电线路保护与故障定位方法。综合利用故障暂态量时域和频域特征，改进了现有的高压交流输电线路故障检测、故障选相与雷击干扰识别方法；基于小波变换、S变换等时频域联合分析方法，研究了灵敏性与可靠性更高的高压交流输电线路超高速方向元件；利用故障电压和故障电流的S 变换及小波变换能量相对熵表征电气量的极性关系，分别给出了适用于交流输电线路和高压直流输电线路的极性比较式纵联保护算法；根据初始行波波头中不同频率成分到达测量点的时间差与故障距离之间的关系，提出了一种基于故障暂态与稳态信号波速差的输电线路单端定位方法；结合行波固有频率主成分、各次固有频率与故障距离的对应关系，构造识别高压直流输电线路区内、区外故障的辅助判据，解决保护区内主判据盲区的拒动问题，并提出了基于行波固有频率的高压直流输电线路故障测距方法。本项目通过对超高速、高可靠性的高压输电线路保护方法与精确的故障定位方法的研究，为电网的安全稳定运行提供了良好的技术参考，具有一定的工程应用价值。