特高压直流输电线路暂态保护研究

发布时间：2018-06-17 01:03

本文选题：特高压直流输电 + 频率特性　；参考：《昆明理工大学》2014年硕士论文

【摘要】：特高压直流输电线路送电距离跨度大,沿途条件复杂,线路发生故障的概率大为增加,亟需一套可靠性高的保护方案来保证输电线路的安全运行；另外输电线路发生故障后,快速准确的故障定位不仅可以迅速排除故障防止故障再次发生,还可以大大节省巡线工作量,特别是直流线路,因其输电距离长、跨度大,故障定位工作显得尤为重要。目前国内的直流输电工程中大多采用ABB和SEIMENS的直流保护系统,其直流线路主保护是行波保护,而行波保护存在可靠性差,在高阻接地时可能会拒动的问题,因此需要研究新的可靠性更高的特高压直流输电线路保护方法。本文在分析特高压直流输电系统边界和输电电路频率特性的基础上做了以下工作： a)分析特高压直流输电线路和“边界”的频率特性,发现当故障点与保护安装点之间的线路长度大于一定值时,线路对高频量的衰减作用将大于边界的衰减作用,现有的直流输电线路暂态保护原理不能实现全线保护。对侧区外的高频故障暂态信号经过特高压直流输电线路和边界的双重衰减到达保护安装点,而特高压直流输电线路的高频故障信号则只经过线路的衰减,据此提出区分对侧区内外故障的特高压直流输电线路单端电压暂态保护原理。对检测到的故障暂态电压信号进行多尺度小波变换,利用对侧区内外故障时高频暂态电压小波能量的差异构造区分对侧区内外故障的判据；通过计算故障后两极线上暂态电压低频段信号比值实现故障选极。大量仿真试验表明该方法有效。 b)研究特高压直流输电系统的对称性,据此提出用保护元件区分对端区内外故障的特高压直流线路双端暂态保护原理。分析和仿真试验表明该暂态保护原理能够保护线路的全长。通过比较两端检测到的故障暂态信号,判断故障位置更靠近整流侧还是逆变侧；对检测到的对端故障电压暂态信号进行多尺度小波变换,利用高频段小波能量与低频段小波能量不同构造区内外故障判据；根据故障后两极线上暂态电压之间的差异构造故障选极判据,仿真结果表明所提方法具有良好的反映过渡电阻的能力 c)分析边界和线路对故障电流的衰减作用,提出区分对侧区内外故障的特高压直流输电线路电流暂态保护原理,利用希尔伯特黄变换求出IMF1瞬时频率,提取瞬时频率中最大值从而判断对侧区内外故障；来自本侧区外和来自对侧故障电流在突变方向上具有明显的差异,并利用积分的方法构造方向判据,提出一种特高压直流输电线路单端电流暂态保护方案,PSCAD仿真结果表明该保护方案效果很好。 d)直流输电线路故障时,高频故障暂态信号将沿线路向两端传播,线路对故障暂态信号高频分量有衰减作用。研究双极特高压直流输电线路频率特性,得到特高压直流输电线路对高频量有衰减作用,线路越长,衰减作用越剧烈的结论。研究基于高频量衰减特性的特高压直流输电线路单端故障测距原理,推导出故障点距测距装置安装点的距离公式,得到基于高频量衰减特性的特高压直流输电线路单端故障测距原理难以准确实现直流输电点线路故障测距的结论。研究基于高频量衰减特性的特高压直流输电线路双端故障测距原理,推导出故障点距测距装置安装点的距离公式,提出频带衰减概念,推导出基于频带衰减的故障距离计算公式。对本文提出的基于高频量衰减特性的特高压直流输电线路双端故障测距原理进行仿真验证,仿真测距结果有较高的准确度。
[Abstract]:The power transmission distance of extra - high voltage direct current transmission line is large , along the road condition is complex , the probability of line fault is greatly increased , a set of high reliability protection scheme is needed to ensure the safe operation of the transmission line ;
In addition , after the transmission line has failed , the fast and accurate fault locating can not only prevent the fault from happening again , but also greatly save the patrol workload , especially the direct current line , because of its long transmission distance , large span and fault location work .

a ) analyzing the frequency characteristics of the special high - voltage direct - current transmission line and the boundary , and finding that when the length of the line between the fault point and the protection installation point is larger than a certain value , the attenuation effect of the line on the high - frequency quantity is greater than the attenuation effect of the boundary ;
The fault selection is realized by calculating the ratio of the transient voltage low - frequency segment signal on the two - pole line after fault . A large number of simulation tests show that the method is effective .

b ) To study the symmetry of ultra high voltage direct current ( HVDC ) transmission system , and propose a protection element to distinguish the two - terminal transient protection principle of special high voltage direct current ( HVDC ) line with internal and external faults . The analysis and simulation tests show that the transient protection principle can protect the whole length of the line . By comparing the fault transient signals detected at both ends , it is determined that the fault location is closer to the rectification side or the inverter side ;
carrying out multi - scale wavelet transformation on the detected transient signal of the opposite - end fault , and utilizing the high - frequency band wavelet energy and the low - frequency band wavelet energy to construct the internal and external fault criteria ;
The fault selection criterion is constructed according to the difference between the transient voltages on the two pole lines after the fault , and the simulation results show that the proposed method has good capability of reflecting the transition resistance .

c ) analyzing the attenuation effect of the boundary and the line on the fault current , and proposing a special high - voltage direct current transmission line current transient protection principle for differentiating the fault on the side area and the outside ;
The transient protection scheme for single - end current of extra - high voltage DC power transmission line is proposed , and the simulation results of PSCAD show that the protection scheme has good effect .

On the basis of the principle of single - end fault location of high - voltage direct current transmission line based on high frequency quantity attenuation characteristic , the distance formula for fault location of DC transmission line based on high frequency quantity attenuation characteristic is obtained .
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM721.1

【参考文献】