本文關(guān)鍵詞： 高壓直流輸電 行波保護 行波固有頻率 線路邊界 小波能量相對熵 縱聯(lián)保護 雷擊干擾 小波能量矩　出處：《西南交通大學》2017年碩士論文　論文類型：學位論文

【摘要】：高壓直流輸電工程具有傳輸功率大、線路造價低的優(yōu)點,相比交流輸電線路更適合于遠距離、大功率輸電,中國的能源分布和電網(wǎng)結(jié)構(gòu)決定了高壓直流輸電具有廣闊的發(fā)展前景。但超長的送電距離、情況復雜的輸電走廊、惡劣的工作條件使直流輸電線路發(fā)生短路、雷擊等事故的概率增加,統(tǒng)計表明線路故障占直流輸電系統(tǒng)故障的一半,因此研究高壓直流輸電線路保護對保障系統(tǒng)的安全穩(wěn)定運行具有至關(guān)重要的作用。為此,論文針對高壓直流輸電線路現(xiàn)有保護誤動率高和高阻故障時保護可靠性差這兩個關(guān)鍵問題開展研究,主要工作有:1)利用行波固有頻率的高壓直流輸電線路縱聯(lián)保護方法。通過總結(jié)現(xiàn)行行波保護存在的問題,進一步利用故障行波頻域特征構(gòu)建保護算法,利用行波固有頻率與輸電線路的故障距離和邊界條件之間的數(shù)學關(guān)系,提出一種基于行波固有頻率的高壓直流輸電線路縱聯(lián)保護方法,可以起到行波保護后備保護的作用,動作于線路高阻故障。2)提出一種基于電壓、電流突變量方向特征的高壓直流輸電線路縱聯(lián)保護方法。在分析高壓直流輸電系統(tǒng)和故障疊加電路的基礎上,利用小波能量相對熵有效地識別高壓直流輸電線路的故障暫態(tài)。給出一種基于小波能量相對熵的縱聯(lián)保護方法可以準確動作于區(qū)內(nèi)故障,保護性能不受故障類型、故障距離、過渡電阻和噪聲的影響。3)將小波能量相對熵計算方法應用于高壓直流輸電線路單端保護。針對現(xiàn)有的高壓直流輸電線路單端保護存在可靠性差、耐過渡電阻能力差的問題,提出一種新的單端保護方法。首先,分析直流線路邊界濾波環(huán)節(jié)的頻率阻抗特性;然后計算濾波環(huán)節(jié)兩側(cè)電流之間的小波能量相對熵,進而描述電流各頻段能量差異;最終構(gòu)造直流線路單端保護判據(jù),可實現(xiàn)區(qū)內(nèi)、外故障的識別。該保護方法原理簡單,能快速、可靠地識別直流線路區(qū)內(nèi)、外故障,具有一定耐過渡電阻能力。4)為防止雷擊干擾時保護誤動,構(gòu)建了一種高壓直流輸電線路雷擊干擾識別元件。雷擊時間會產(chǎn)生大量高頻分量,對需要識別行波波頭的行波保護和利用故障高頻分量的保護影響比較大。論文從小波分析理論出發(fā),利用小波能量矩分析故障性暫態(tài)和非故障性暫態(tài)情況下暫態(tài)信號能譜值在各個頻段的分布,實現(xiàn)對雷擊未故障、雷擊故障以及普通短路故障的準確、快速識別。論文利用多種時頻分析方法探討了直流輸電線路保護及雷擊干擾識別的具體方案,解決了現(xiàn)有直流線路保護可靠性不高、耐受過渡電阻能力差的問題,可以為高壓直流輸電線路保護的相關(guān)研究提供支持。
[Abstract]:HVDC transmission project has the advantages of large transmission power and low line cost. Compared with AC transmission line, it is more suitable for long-distance and high-power transmission. China's energy distribution and power network structure determine that HVDC transmission has a broad development prospects, but long transmission distance, complex transmission corridor, poor working conditions make HVDC transmission lines short circuit. The probability of accidents such as lightning stroke increases, and the statistics show that the line faults account for half of the faults of HVDC transmission system. Therefore, it is very important to study the protection of HVDC transmission line to ensure the safe and stable operation of the system. This paper focuses on the two key problems of high misoperation rate and low reliability of protection for HVDC transmission lines. The main work is: (1) using the traveling wave natural frequency of HVDC transmission line longitudinal protection method. Through summing up the existing problems of traveling wave protection, further using the fault traveling wave frequency domain features to construct the protection algorithm. Based on the mathematical relationship between natural frequency of traveling wave and fault distance and boundary condition of transmission line, a longitudinal protection method for HVDC transmission line based on natural frequency of traveling wave is proposed. It can act as back-up protection of traveling wave protection, which is applied to line high resistance fault. 2) A voltage based method is proposed. Longitudinal protection method for HVDC transmission lines with directional characteristics of current abrupt changes. Based on the analysis of HVDC transmission system and fault superposition circuit. Using the relative entropy of wavelet energy to identify the fault transient of HVDC transmission line effectively, a longitudinal protection method based on relative entropy of wavelet energy is presented. Protection performance is not subject to fault type, fault distance. The effect of transition resistance and noise. 3) the wavelet energy relative entropy method is applied to the single-terminal protection of HVDC transmission line. The reliability of the existing single-terminal protection of HVDC transmission line is poor. A new single-terminal protection method is proposed for the problem of poor resistance resistance. Firstly, the frequency impedance characteristics of the boundary filtering link of DC line are analyzed. Then the relative entropy of wavelet energy between the two sides of the filter is calculated, and then the energy difference of each frequency band of the current is described. Finally, the single terminal protection criterion of DC line is constructed, which can realize the identification of fault in and out of the DC line. This protection method is simple in principle and can be used to identify the fault in and out of the DC line quickly and reliably. In order to prevent the maloperation of lightning interference, a lightning strike identification element for HVDC transmission line is constructed. The lightning strike time will produce a large number of high frequency components. It has great influence on the traveling wave protection which needs to identify the traveling wave head and the protection using the fault high frequency component. This paper is based on the theory of wave analysis. Wavelet energy moments are used to analyze the distribution of the energy spectrum of transient signals in the fault transient and non-fault transient conditions, so as to achieve the accuracy of lightning failure, lightning strike fault and common short-circuit fault. Rapid identification. This paper discusses the specific scheme of DC transmission line protection and lightning disturbance identification by using various time-frequency analysis methods, and solves the problem that the reliability of the existing DC line protection is not high. The problem of poor resistance resistance can support the research of HVDC transmission line protection.
【學位授予單位】：西南交通大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TM773

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