本文選題：高壓直流　切入點：輸電線路　出處：《山東大學》2014年博士論文

【摘要】：直流輸電線路保護和故障測距是直流輸電工程保護系統(tǒng)的重要組成部分,擔負著快速檢測和清除線路故障的任務,其運行性能將直接影響直流輸電系統(tǒng)和電網的安全運行。統(tǒng)計研究表明直流輸電線路已成為直流輸電系統(tǒng)中故障率最高的元件,而直流輸電線路保護的正確動作率只有50%。我國直流輸電工程的發(fā)展位于世界前列,但對現有直流輸電線路保護與故障測距裝置核心技術的掌握仍然不足,缺乏系統(tǒng)的理論支持,已投運直流輸電工程的保護系統(tǒng)大多采用ABB和SIEMENS兩家公司的技術路線。提高我國高壓直流輸電線路保護與故障測距的理論水平和加快直流保護系統(tǒng)的自主研發(fā)勢在必行。 現己投運的直流輸電線路主保護易受雷電、換相失敗等暫態(tài)過程的干擾,耐受過渡電阻能力有限,判據門檻值整定計算復雜。國內外學者致力于對現有直流輸電線路主保護進行改進或提出新型主保護原理,其中部分保護新原理存在理論不完備、保護判據所用信號能量小、對裝置采樣率要求高、缺乏整定依據或整定計算依賴仿真結果等問題。高壓直流輸電線路故障測距所采用的原理可分為行波法和故障分析法。目前運行中的直流輸電線路故障測距裝置均采用行波原理,行波故障測距的可靠性在高阻接地故障和波頭識別失敗時受限。基于故障分析法的故障測距原理性能穩(wěn)定,故障測距精度一般沒有行波法高,部分原理耐受過渡電阻能力有限。 全面深入的高壓直流輸電系統(tǒng)故障暫態(tài)分析可為直流輸電線路保護與故障測距原理的研究工作奠定基礎。本文研究了高壓直流輸電系統(tǒng)故障暫態(tài)特性分析需要考慮的影響因素,深入分析了相應影響機理,給出了仿真案例實現方案,并對直流線路電氣量的暫態(tài)特征進行分析；提出了耐受過渡電阻能力強、判據門檻值整定不依賴于仿真計算的高壓直流輸電線路主保護原理和可靠性良好、測距精度高、耐受過渡電阻能力強的直流輸電線路雙端行波故障測距新算法。主要研究內容及結論如下： (1)高壓直流輸電系統(tǒng)故障暫態(tài)特性研究。 現有直流輸電系統(tǒng)故障暫態(tài)分析相關內容大多作為線路保護與故障測距研究的考慮因素出現在文獻的理論分析和仿真驗證中,受文獻篇幅和考查內容所限。本文從直流輸電線路保護與故障測距角度出發(fā),開展了較為全面的高壓直流輸電系統(tǒng)故障暫態(tài)特性分析。對直流輸電系統(tǒng)的基本控制原理和控制系統(tǒng)的分層結構進行研究,分析了控制系統(tǒng)對故障暫態(tài)的響應時間和電氣量的故障穩(wěn)態(tài)值；研究了兩端雙極直流輸電系統(tǒng)多種可能運行方式的運行條件與控制策略,并對不同故障前運行方式下直流線路故障電壓電流的暫態(tài)特征進行了對比分析；分析了直流濾波環(huán)節(jié)的阻抗特性及其對故障后暫態(tài)過程的影響,提出在直流輸電線路故障暫態(tài)電壓電流信號的低頻帶特征分析中,可將直流濾波器和平波電抗器視為固定阻抗；分析了故障類型、故障位置和過渡電阻值對直流線路故障電壓電流暫態(tài)特征的影響；研究直流輸電線路的雷電放電計算模型,給出了雷擊暫態(tài)仿真中雷電流源、桿塔模型、絕緣子閃絡模型和輸電線路模型的仿真建模方法,對故障性雷擊和雷擊干擾下直流線路電壓電流的暫態(tài)特征進行了分析；研究了直流輸電系統(tǒng)換相失敗的形成機理、判斷標準和單雙極換相失敗的仿真方法,分析了換相失敗情況下直流線路電壓電流的暫態(tài)特征。以上工作可為后續(xù)高壓直流輸電系統(tǒng)故障暫態(tài)分析研究提供直接有效的參考,為直流輸電線路保護與故障測距原理研究奠定基礎。 (2)考慮故障選極的高壓直流輸電線路保護原理研究。 分析了故障后直流輸電線路電壓突變量的暫態(tài)幅值特征,發(fā)現故障極線路的電壓突變量幅值大于健全極,且電壓突變量的積分值能夠更好地體現這一特征；提出了利用兩極線路電壓突變量積分值的比值構造的故障選極判據,給出了判據門檻值整定方法；分析了故障后直流輸電線路電流突變量的暫態(tài)極性特征,發(fā)現故障極線路兩端電流突變量的極性在區(qū)內故障時相反,在區(qū)外故障時相同；提出了利用故障極線路兩端電流突變量極性構造的區(qū)內故障判據,并采用平穩(wěn)小波變換提取電流突變量的極性。由此構成的高壓直流輸電線路主保護滿足選擇性和速動性的要求,判據門檻值整定方法簡潔且不依賴于仿真計算；在10kHz及以上的采樣頻率范圍內均可實現；只需對端電流突變量的極性信息,對通信通道的可靠性要求較低,尤其適用于需要選擇故障極的情況。 基于中國銀東±660kV直流輸電工程的實際參數,本文建立了±660kV高壓直流輸電系統(tǒng)的PSCAD仿真模型,利用仿真數據驗證了考慮故障選極的高壓直流輸電線路保護原理在不同故障情況下的動作特性。仿真結果表明,該保護原理在兩端雙極直流輸電系統(tǒng)的多種運行方式下能夠快速選出故障極和判別直流輸電線路保護區(qū)內故障,耐受過渡電阻能力強,可實現高壓直流輸電線路的全線速動保護。 (3)基于電壓和電流突變量方向的高壓直流輸電線路保護原理研究。 考慮故障選極的直流輸電線路保護一般在極-極故障這一罕有情況發(fā)生時不能正確工作,因此,本文提出了直接判別直流線路保護區(qū)內故障的直流輸電線路保護原理。對故障后直流線路電壓和電流突變量的暫態(tài)特征分析發(fā)現,直流輸電線路兩端電壓和電流突變量的方向在直流輸電線路保護區(qū)內故障和區(qū)外故障時不同；通過將電壓和電流突變量在一段時間內的積分值與設定門檻值比較,提出了電壓和電流突變量的方向判據；通過比較線路兩端電壓和電流突變量的方向,提出了基于電壓和電流突變量方向的高壓直流輸電線路保護原理。該保護原理的判據門檻值整定不依賴于仿真計算；僅利用線路兩端電壓和電流突變量的方向信息便可準確識別直流輸電線路保護區(qū)內故障,對通信通道的可靠性要求不高；不需要進行采樣數據同步處理；電壓和電流突變量方向判據僅計算5ms數據窗內的積分值,對數據計算速度和采樣頻率要求較低,采樣頻率為10kHz及以上時即可滿足保護判據計算要求。 利用±660kV高壓直流輸電系統(tǒng)的PSCAD仿真數據對該保護原理在不同故障情況下的動作特性進行了驗證。該保護原理在直流線路保護區(qū)內故障性雷擊、高阻接地故障和極-極故障時能準確動作,在雷擊干擾和線路保護區(qū)外故障等情況下不誤動,能實現直流輸電線路的全線準確速動保護,適用于雙極直流輸電系統(tǒng)的多種運行方式,實用性強。 (4)高壓直流輸電線路雙端行波故障測距新算法研究。 分析了故障行波在直流輸電線路上的傳播特點,發(fā)現可用行波波頭傳播特性曲線表征故障行波在線路上的傳播過程,聯立直流輸電線路本端和對端的行波波頭傳播特性曲線可計算出故障位置。本文通過檢測沿線分布電流的初次突變時刻求出線路兩端的行波波頭傳播特性曲線,提出了直流輸電線路雙端行波故障測距新算法及其實現策略。該故障測距算法無需另外增加測量點,對通道的可靠性要求不高,算法數據窗口短,可不受控制系統(tǒng)調整的影響�；赑SCAD的仿真結果表明,本文故障測距算法在兩端雙極直流輸電系統(tǒng)的多種可能運行方式下,在線路全長范圍內均能實現準確測距,故障點靠近線路中點時測距準確度升高,測距精度不受過渡電阻值和直流線路出口故障的影響,最大故障測距誤差約為線路全長的0.1129%。相較于現有高壓直流輸電工程中應用的雙端行波故障測距,雖然本文故障測距算法的計算過程較為復雜,但是其可靠性、抗干擾能力和耐受過渡電阻能力有顯著提高,而故障測距誤差與之基本相同,保留了行波故障測距原理定位精度高的優(yōu)點。因此,本文故障測距算法可作為現有直流輸電線路雙端行波故障測距的有效補充。 本文研究內容及成果對提高直流輸電線路保護與故障測距理論水平有重要學術價值,可為構建快速可靠的直流保護系統(tǒng)、加快直流系統(tǒng)故障恢復速度和保護設備的自主研發(fā)等提供理論支持,選題具有工程實用意義。
[Abstract]:DC transmission line protection and fault distance measurement is an important part of DC transmission project protection system . The operation performance of DC transmission line is the highest in DC power transmission system , and its operation performance will directly affect the safe operation of DC power transmission system and power grid . The statistical study shows that DC transmission line has become the highest fault rate in DC transmission system , and the correct operation rate of DC transmission line protection is only 50 % .

The main protection of HVDC transmission line is easy to be disturbed by the transient processes such as lightning , failure of phase change and so on . It has limited ability to withstand transient resistance and complicated calculation of threshold value . The principle of fault distance measurement of HVDC transmission line is limited . The fault location principle of HVDC transmission line is limited . The fault location principle of HVDC transmission line is stable . The fault location accuracy is generally not high , and partial principle is limited to the ability of transient resistance .

The transient analysis of high voltage direct current power transmission system can provide the foundation for the research of DC transmission line protection and fault location principle . In this paper , the influence factors of transient characteristic analysis of HVDC transmission system are studied , the corresponding influence mechanism is deeply analyzed , the simulation case realization scheme is given , and the transient characteristics of the electrical quantity of DC line are analyzed .
In this paper , the new algorithm of double - end travelling wave fault location based on high voltage direct current transmission line with strong capability of resisting transient resistance is put forward , which is not dependent on the main protection principle and reliability of high voltage direct current transmission line with high reliability , high precision and high resistance to transition resistance . The main research contents and conclusions are as follows :

( 1 ) Study on transient characteristics of HVDC system fault .

In this paper , the analysis of the transient characteristics of HVDC transmission system is carried out based on the protection and fault location of DC transmission line . The basic control principle of HVDC transmission system and the layered structure of control system are studied , and the response time of the control system to fault transient and the fault steady state value of electric quantity are analyzed .
The operating conditions and control strategies of a variety of possible operating modes of the two - pole HVDC system are studied , and the transient characteristics of DC line fault voltage current under different pre - fault modes of operation are compared .
This paper analyzes the impedance characteristic of DC filter and its effect on transient process after fault , and puts forward that the DC filter can be regarded as fixed impedance in low frequency band characteristic analysis of transient voltage current signal of DC transmission line .
The effect of fault type , fault location and transitional resistance value on transient characteristics of DC line fault voltage is analyzed .
The lightning discharge calculation model of DC transmission line is studied , and the simulation modeling method of lightning current source , pole tower model , insulator flashover model and transmission line model in lightning transient simulation is given . Transient characteristics of DC line voltage current under fault lightning stroke and lightning stroke are analyzed .
This paper studies the formation mechanism of commutation failure of HVDC transmission system , judges the standard and the simulation method of single bipolar commutation failure , analyzes the transient characteristics of DC line voltage current in the case of commutation failure . The above work can provide a direct and effective reference for the transient analysis of the subsequent high voltage DC transmission system , and lays a foundation for the research of protection and fault location principle of DC transmission line .

( 2 ) To study the protection principle of HVDC transmission line considering fault selection .

The transient amplitude characteristic of the voltage mutation of DC transmission line after fault is analyzed . It is found that the magnitude of the voltage change of the fault pole line is greater than the perfect pole , and the integral value of the voltage mutation quantity can better reflect this feature ;
In this paper , the fault selection criterion of the ratio structure of the two - pole line voltage mutational quantity integral value is proposed , and the criterion threshold value setting method is given .
The transient polarity characteristics of the current abrupt change of DC transmission line after fault are analyzed , and it is found that the polarity of the current mutation at the two ends of the fault line is the same as that of the fault in the region , and the fault is the same in the area outside the fault line .
In this paper , a fault criterion is proposed in the region using the polarity of the current abrupt change in the fault pole line , and the polarity of the current mutation is extracted by the stationary wavelet transform . The main protection of the high voltage direct current transmission line is satisfied with the requirement of selectivity and quick action , and the criterion threshold value setting method is simple and independent of the simulation calculation ;
can be realized in the sampling frequency range of 10 kHz and above ;
only the polarity information of the terminal current mutation quantity is needed , the reliability requirement of the communication channel is low , and the method is particularly suitable for the case of needing to select a fault pole .

The PSCAD simulation model of 鹵 660kV HVDC transmission system is established based on the actual parameters of the HVDC transmission project of Yindong 鹵 660kV in China . The simulation data is used to verify the operating characteristics of HVDC transmission line protection principle under different fault conditions .

( 3 ) Research on protection principle of HVDC transmission line based on voltage and current abrupt change direction .

In this paper , the principle of direct current transmission line protection for direct current transmission line protection in DC transmission line is presented . The transient characteristic analysis of DC line voltage and current mutation rate after fault has been found , and the direction of voltage and current mutation of DC transmission line is different in the fault and out - of - area fault of DC transmission line protection zone .
The direction criterion of voltage and current mutation is proposed by comparing the integration value of voltage and current abrupt change over a period of time with the set threshold value .
In this paper , the protection principle of HVDC transmission line based on voltage and current abrupt change direction is proposed by comparing the voltage of two ends of the line and the direction of current abrupt change , and the criterion threshold value of the protection principle is not dependent on the simulation calculation ;
the fault in the DC transmission line protection area can be accurately recognized by using the directional information of the voltage and the current mutation amount of the two ends of the line , and the reliability requirement of the communication channel is not high ;
sampling data synchronization processing is not required ;
The voltage and current abrupt change direction criterion only calculates the integral value in the 5 ms data window , and can meet the protection criterion calculation requirement when the data calculation speed and the sampling frequency requirement are low , and the sampling frequency is 10kHz and above .

The operation characteristics of the protection principle in different fault conditions are verified by PSCAD simulation data of 鹵 660kV HVDC transmission system .

( 4 ) The new algorithm of double - end travelling wave fault location of HVDC transmission line .

The propagation characteristics of fault traveling wave in DC transmission line are analyzed . It is found that the propagation process of fault traveling wave on the line can be characterized by the characteristic curve of the traveling wave head propagation characteristic . The fault location accuracy is not affected by the transition resistance value and the DC line outlet fault . The fault location error is about 0.1129 % of the total length of the line . The fault location error is basically the same as that of the existing high voltage direct current transmission project .

The research contents and achievements have important academic value for improving the theoretical level of DC transmission line protection and fault ranging theory , which can provide theoretical support for the construction of fast and reliable DC protection system , speed up the recovery speed of DC system fault and independent R & D of protection equipment .

【學位授予單位】：山東大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TM75

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本文編號：1687827