本文選題：對稱分量法 + 輸電線路解耦　； 參考：《廣西大學》2017年碩士論文

【摘要】：電力系統(tǒng)在運行過程中,會發(fā)生各種不同類型的故障,而電力系統(tǒng)故障的分析計算對于電力系統(tǒng)的規(guī)劃設計、事故分析以及電力系統(tǒng)的整定運行都有著十分重要的指導作用,所以人們對電力系統(tǒng)故障分析計算方法的研究從來沒有停止過。我國電源點和負荷中心分布極其不合理,基于這種基本國情,高壓、特高壓輸電被提上了日程;但出于經(jīng)濟和方便等角度的考慮,高壓、特高壓輸電線路一般不進行換位,這就造成了輸電線路三相參數(shù)的不對稱。本文介紹了一種運用對稱分量法來分析計算三相參數(shù)不對稱的輸電線路故障的計算方法,論文從磁鏈的角度出發(fā),將三相阻抗表示為關于三相電流的關系式,實現(xiàn)了輸電線路三相阻抗的解耦。運用網(wǎng)絡等值理論,將三相參數(shù)不對稱的輸電線路等效變換為發(fā)生了某種類型的斷線故障的三相參數(shù)對稱的輸電線路,當三相參數(shù)不對稱的輸電線路有故障發(fā)生時,則可以看作是等效變換后的三相參數(shù)對稱的輸電線路發(fā)生了復雜故障,對于復雜故障的計算,本文運用對稱分量法結合口網(wǎng)絡理論來進行分析計算�？诰W(wǎng)絡理論就是把每一個故障點看作是一個故障端口,根據(jù)故障端口繪制三序網(wǎng)絡圖,列寫三序節(jié)點導納矩陣,求逆得到三序阻抗矩陣,根據(jù)三序阻抗矩陣可以得到三序口阻抗口矩陣,列寫三序電壓方程和故障邊界條件方程,聯(lián)立方程求解就可以得到故障時的電壓電流。三相阻抗是關于三相電流的表達式,當流過輸電線路的三相電流發(fā)生改變時等效三相阻抗也會發(fā)生改變,對于輸電線路初始阻抗的計算,假設流過輸電線路的初始電流是三相對稱的。用初始的輸電線路三相阻抗進行故障計算,可以得到初始的故障電壓和電流;將流過輸電線路的初始故障電流代回輸電線路三阻抗公式,又可以求得新的輸電線路三相阻抗,從而得到新的輸電線路的正負零序導納,從而可以得到新的三序節(jié)點導納矩陣,求逆得到新的三序阻抗矩陣,根據(jù)三序阻抗矩陣可以求得新的三序口阻抗矩陣,列寫新的三序電壓方程和故障邊界條件方程,求解出新的故障電壓電流,重復以上步驟,直到前后兩次計算的故障電流的百分誤差不超過1%;此時,得到的電壓、電流就是輸電線路三相參數(shù)不對稱發(fā)生故障時的故障電壓、電流。通過matlab編程對本文算法進行編程,利用EMTP對系統(tǒng)模型進行仿真,將兩者的結果進行比較,驗證本文算法的正確性。
[Abstract]:In the process of power system operation, various kinds of faults will occur, and the analysis and calculation of power system faults play an important role in the planning and design of power system, the analysis of accidents and the setting operation of power system. Therefore, the study of power system fault analysis and calculation methods has never stopped. The distribution of power points and load centers in China is extremely unreasonable. Based on this basic situation, high-voltage and ultra-high voltage transmission lines are put on the agenda. However, for reasons of economy and convenience, high-voltage and ultra-high voltage transmission lines generally do not carry out transposition. This results in the asymmetry of three-phase parameters of transmission lines. In this paper, a method of calculating the fault of transmission lines with asymmetric three-phase parameters by using symmetric component method is introduced. In this paper, the three-phase impedance is expressed as the relation of three-phase current from the point of view of flux linkage. The decoupling of three-phase impedance of transmission line is realized. By using the network equivalence theory, the three-phase transmission line with asymmetric parameters is transformed into a transmission line with a certain type of break-line fault. When the three-phase parameter asymmetric transmission line has a fault, It can be regarded as the complex fault of the transmission line with symmetrical three-phase parameters after equivalent transformation. For the calculation of the complex fault, the symmetric component method combined with the theory of port network is used to analyze and calculate the complex fault. The theory of port network is to treat each fault point as a fault port, draw the three-sequence network diagram according to the fault port, write the three-sequence node admittance matrix, and obtain the three-sequence impedance matrix by inverse. According to the three-sequence impedance matrix, the three-sequence impedance port matrix can be obtained, and the three-sequence voltage equation and the fault boundary condition equation can be set up, and the voltage and current in the fault can be obtained by solving the simultaneous equation. Three-phase impedance is the expression of three-phase current. When the three-phase current of transmission line changes, the equivalent three-phase impedance will also change. Assume that the initial current flowing through the transmission line is three-phase symmetric. The initial fault voltage and current can be obtained by using the initial three-phase impedance of the transmission line, and the three-phase impedance formula of the transmission line can be replaced by the initial fault current flowing through the transmission line, and a new three-phase impedance of the transmission line can be obtained. Thus, the positive and negative zero-sequence admittance of a new transmission line can be obtained, a new three-sequence node admittance matrix can be obtained, a new three-sequence impedance matrix can be obtained by inverse, and a new three-sequence impedance matrix can be obtained according to the three-sequence impedance matrix. Write a new three-sequence voltage equation and a fault boundary condition equation, solve the new fault voltage and current, repeat the above steps until the error of the fault current calculated twice before and after is less than 1 percent; in this case, the resulting voltage, Current is the fault voltage and current when the three-phase parameters of transmission line are not symmetrical. The algorithm is programmed by matlab, the system model is simulated by EMTP, and the results are compared to verify the correctness of the algorithm.
【學位授予單位】：廣西大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TM75

【參考文獻】

相關期刊論文 前10條

1 傅旭;付覽，

本文編號：1909158