柔性直流输电线路故障测距研究

发布时间：2018-02-26 15:49

本文关键词： 柔性直流输电故障测距 S变换行波波头行波波速　出处：《山东大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着电力电子技术的不断创新和发展,柔性直流输电(VSC-HVDC)系统的电压等级和输送容量也不断提高。一旦直流输电线路发生故障,可靠、精确的故障测距对于及时修复线路故障、保障VSC-HVDC系统的正常稳定运行具有极其重要的作用。因此,研究可靠、精确的VSC-HVDC线路的故障测距算法具有十分重要的理论和现实意义。目前,实际VSC-HVDC工程中的故障测距装置均采用行波原理,行波故障测距算法的可靠性依赖于故障行波波头的准确检测与识别。而最为常用的小波变换方法,在线路发生远距离故障和高阻故障时,特别是在直流电缆当中,适用性较差;而且现有的直流输电线路行波故障测距算法也未能充分考虑行波波速的依频变化特性,且关于直流电缆的测距算法研究较少。本文在深入研究S变换理论的基础上,将S变换应用到直流输电线路故障行波信号的处理和分析中,分别提出了适用于直流架空线和直流电缆的行波故障测距算法。主要研究内容及结论如下:1、深入分析了 S变换理论在直流输电线路故障测距中的可行性。阐述了 S变换的基本原理,分析其基本性质在处理故障行波信号中的优势;深入分析S变换结果特点,研究其检测与识别行波波头的基本原理;仿真验证了 S变换在检测行波波头中的准确性和可靠性,并与小波变换(SWT)对比分析了其在检测行波波头中的优越性。2、提出了一种基于S变换的VSC-HVDC架空线路单端行波故障测距算法。分析VSC-HVDC系统结构特点,总结故障行波在直流输电线路中的传播规律,给出了根据极性识别故障行波波头的方法;利用S变换分析并提取故障行波信号不同频率分量的幅值-时间曲线,分别用于检测不同的行波波头,结果更为直观、易于识别,提高了波头的检测精度,并保证了在线路全长和高阻情况下的适用性和准确性;根据不同波头之间的时间差消除了波速变量的影响,实现了故障的准确测距。基于PSCAD的仿真分析表明,该测距算法对不同的故障距离均具有很好的适用性,且不受过渡电阻的影响。3、分析直流电缆的结构、参数变化特性,研究了适用于直流电缆的相模变换(解耦)方法:分析直流电缆的模量故障行波时频变化特性,并基于此,提出了一种利用行波时频特征和S变换的VSC-HVDC电缆故障测距算法。(1)深入研究了带铠装层的直流电缆模型,分析其参数的依频变化特性;研究其参数矩阵的特点,提出了一种直流电缆(考虑铠装层)的相模变换方法;分析了其相模变换所得各模量的变化特性,为研究直流电缆的行波测距方法提供了理论基础;(2)研究分析直流电缆的故障行波时频变化特征,总结行波衰减和色散对行波波头特征的影响;在此基础上,利用S变换准确提取并检测故障行波波头各频率分量的到达时刻,实现了行波波头的依频检测,提高了波头的检测精度,并克服了过渡电阻的影响;利用最小二乘法拟合行波波头相应频率的波速,实现了波速的优化选取;根据平稳小波变换(SWT)结果识别行波波头极性,判断故障的类型,进而实现故障的准确测距。基于PSCAD的仿真分析表明,相较于传统固定波速的测距算法,该算法测距精度更高,适用性更好,且具有很好的耐受过渡电阻能力。
[Abstract]:With the continuous innovation and development of power electronic technology, flexible DC transmission (VSC-HVDC) system voltage level and transmission capacity is also increasing. Once the DC transmission line failure, reliable and accurate fault location for transmission line fault repair time, plays a very important role in ensuring normal stable operation of VSC-HVDC system. Therefore, research on reliable that has very important theoretical and practical significance of the accurate fault location algorithm for VSC-HVDC line. At present, the actual fault location device in the VSC-HVDC project using the traveling wave principle, measuring the reliability of traveling wave fault distance algorithm relies on accurate fault detection and identification of the traveling wave head. The most commonly used method in wavelet transform, remote fault and the high resistance line failure, especially in the DC cable, poor applicability; and the existing DC transmission line fault location algorithm Law also failed to fully consider the frequency variation characteristics according to the wave speed, and a DC cable location algorithm research. Based on the in-depth study of S transform theory, S transform is applied to the processing and analysis of fault signals of HVDC transmission lines, are proposed for traveling wave fault location algorithm for DC overhead line and the DC cable. The main research contents and conclusions are as follows: 1, in-depth analysis of the S transform theory feasibility in fault location of DC transmission lines. This paper introduced the principle of S transform, analyzes its basic properties in fault line signal strengths; in-depth analysis of the S transform the characteristics, basic principle of its detection with the recognition of the traveling wave head; the simulation results show that S transform in detection accuracy and reliability of the traveling wave head, and wavelet transform (SWT) was analyzed in the detection of traveling wave head in. The.2 presents a VSC-HVDC overhead line S transform single terminal traveling wave fault location algorithm based on the analysis of system structure characteristics of VSC-HVDC, summarizes the propagation of fault in DC transmission line, is proposed according to the method of polarity identification of fault traveling wave; amplitude by S transform analysis and extraction of fault traveling wave signals of different frequency components of the time curve were used to detect the different traveling wave head, the result is more intuitive, easy to identify, improve the detection accuracy of wave head, and ensure the full length and high resistance line under the condition of applicability and accuracy; according to the time difference between different wave to eliminate the effect of wave velocity variable, to achieve accurate fault location. It shows that the analysis based on the PSCAD simulation, the ranging algorithm has very good applicability to various fault distances, and is not affected by the transition resistance.3, analysis of DC cable The structure, change parameters, phase mode transformation for the analysis of DC cable (decoupling) methods: frequency analysis of modulus variation characteristics of fault traveling wave DC cable, and based on this, puts forward the VSC-HVDC cable fault location algorithm using a traveling wave time-frequency feature and S transform. (1) studied the DC cable model of armored layer, frequency variation characteristics according to the analysis of its parameters; study the characteristics of the parameter matrix, a DC cable (considering armoured layer) phase model transformation method; analyzed the variation characteristics of the phase mode transformation the modulus, provides a theoretical basis for the study of DC cable fault location method; (2) the frequency characteristics change of fault analysis of DC cable, summarizes the wave attenuation and dispersion of travelling wave characteristics; on this basis, accurate extraction and detection of fault traveling wave head of each frequency component by using S transform The arrival time of the traveling wave frequency detection, improve the detection accuracy of wave head, and overcome the influence of transition resistance; using the least squares fitting wave traveling wave head corresponding frequency, the velocity of optimal selection; stationary wavelet transform (SWT) according to the results of the recognition of traveling wave polarity. Determine the type of fault, and then realize the accurate location of faults. Analysis shows that based on the PSCAD simulation, compared with the traditional fixed velocity ranging algorithm, the algorithm has higher accuracy, better applicability, and has a resistive tolerance as well.

【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM75

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