本文選題：特高壓直流輸電 + 頻率特性��； 參考：《昆明理工大學》2014年碩士論文

【摘要】：特高壓直流輸電線路送電距離跨度大,沿途條件復雜,線路發(fā)生故障的概率大為增加,亟需一套可靠性高的保護方案來保證輸電線路的安全運行；另外輸電線路發(fā)生故障后,快速準確的故障定位不僅可以迅速排除故障防止故障再次發(fā)生,還可以大大節(jié)省巡線工作量,特別是直流線路,因其輸電距離長、跨度大,故障定位工作顯得尤為重要。目前國內(nèi)的直流輸電工程中大多采用ABB和SEIMENS的直流保護系統(tǒng),其直流線路主保護是行波保護,而行波保護存在可靠性差,在高阻接地時可能會拒動的問題,因此需要研究新的可靠性更高的特高壓直流輸電線路保護方法。本文在分析特高壓直流輸電系統(tǒng)邊界和輸電電路頻率特性的基礎(chǔ)上做了以下工作： a)分析特高壓直流輸電線路和“邊界”的頻率特性,發(fā)現(xiàn)當故障點與保護安裝點之間的線路長度大于一定值時,線路對高頻量的衰減作用將大于邊界的衰減作用,現(xiàn)有的直流輸電線路暫態(tài)保護原理不能實現(xiàn)全線保護。對側(cè)區(qū)外的高頻故障暫態(tài)信號經(jīng)過特高壓直流輸電線路和邊界的雙重衰減到達保護安裝點,而特高壓直流輸電線路的高頻故障信號則只經(jīng)過線路的衰減,據(jù)此提出區(qū)分對側(cè)區(qū)內(nèi)外故障的特高壓直流輸電線路單端電壓暫態(tài)保護原理。對檢測到的故障暫態(tài)電壓信號進行多尺度小波變換,利用對側(cè)區(qū)內(nèi)外故障時高頻暫態(tài)電壓小波能量的差異構(gòu)造區(qū)分對側(cè)區(qū)內(nèi)外故障的判據(jù)；通過計算故障后兩極線上暫態(tài)電壓低頻段信號比值實現(xiàn)故障選極。大量仿真試驗表明該方法有效。 b)研究特高壓直流輸電系統(tǒng)的對稱性,據(jù)此提出用保護元件區(qū)分對端區(qū)內(nèi)外故障的特高壓直流線路雙端暫態(tài)保護原理。分析和仿真試驗表明該暫態(tài)保護原理能夠保護線路的全長。通過比較兩端檢測到的故障暫態(tài)信號,判斷故障位置更靠近整流側(cè)還是逆變側(cè)；對檢測到的對端故障電壓暫態(tài)信號進行多尺度小波變換,利用高頻段小波能量與低頻段小波能量不同構(gòu)造區(qū)內(nèi)外故障判據(jù)；根據(jù)故障后兩極線上暫態(tài)電壓之間的差異構(gòu)造故障選極判據(jù),仿真結(jié)果表明所提方法具有良好的反映過渡電阻的能力 c)分析邊界和線路對故障電流的衰減作用,提出區(qū)分對側(cè)區(qū)內(nèi)外故障的特高壓直流輸電線路電流暫態(tài)保護原理,利用希爾伯特黃變換求出IMF1瞬時頻率,提取瞬時頻率中最大值從而判斷對側(cè)區(qū)內(nèi)外故障；來自本側(cè)區(qū)外和來自對側(cè)故障電流在突變方向上具有明顯的差異,并利用積分的方法構(gòu)造方向判據(jù),提出一種特高壓直流輸電線路單端電流暫態(tài)保護方案,PSCAD仿真結(jié)果表明該保護方案效果很好。 d)直流輸電線路故障時,高頻故障暫態(tài)信號將沿線路向兩端傳播,線路對故障暫態(tài)信號高頻分量有衰減作用。研究雙極特高壓直流輸電線路頻率特性,得到特高壓直流輸電線路對高頻量有衰減作用,線路越長,衰減作用越劇烈的結(jié)論。研究基于高頻量衰減特性的特高壓直流輸電線路單端故障測距原理,推導出故障點距測距裝置安裝點的距離公式,得到基于高頻量衰減特性的特高壓直流輸電線路單端故障測距原理難以準確實現(xiàn)直流輸電點線路故障測距的結(jié)論。研究基于高頻量衰減特性的特高壓直流輸電線路雙端故障測距原理,推導出故障點距測距裝置安裝點的距離公式,提出頻帶衰減概念,推導出基于頻帶衰減的故障距離計算公式。對本文提出的基于高頻量衰減特性的特高壓直流輸電線路雙端故障測距原理進行仿真驗證,仿真測距結(jié)果有較高的準確度。
[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 .
【學位授予單位】：昆明理工大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TM721.1

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