雙饋風電場接入對送出線路繼電保護的影響及改善措施
發(fā)布時間：2019-02-18 09:15
【摘要】：面對全球范圍內日益嚴峻的化石能源枯竭和環(huán)境污染問題,風力發(fā)電作為可再生能源發(fā)電的重要代表之一,近年來得到了迅速的發(fā)展,其中雙饋風力發(fā)電機以能量轉換效率高,易于實現(xiàn)有功、無功功率解耦控制等優(yōu)勢,在風電場中得到了廣泛的應用。我國風電多以大規(guī)模集中式并網(wǎng)為主,具有集群開發(fā)、弱電網(wǎng)接入、長距離外送的特點,風電獨特的故障特性給送出線路距離保護和重合閘帶來了新的問題,因此研究雙饋風電場接入對送出線路繼電保護的影響及改善措施,對于提高繼電保護動作可靠性、增強電網(wǎng)抵御故障的能力、保障電網(wǎng)的安全穩(wěn)定運行等具有重要意義。本文首先研究了雙饋風力發(fā)電機的運行原理和控制策略,結合雙饋風電場典型并網(wǎng)結構,在DIg SILENT/Power Factory中搭建了雙饋風電場詳細模型和等值模型,并在穩(wěn)態(tài)和故障暫態(tài)下驗證了模型等值的可行性。理論分析了雙饋風電場的阻抗特性、弱饋特性和電流非工頻特性,基于搭建的雙饋風電場等值模型,仿真研究了風電場在送出線路不同類型故障下的電壓、電流特性,證明了風電場故障特性理論分析的正確性。然后,結合雙饋風電場的故障特性,研究了雙饋風電場接入對送出線路距離保護的影響:受弱饋特性影響,當經(jīng)過渡電阻故障時,距離保護測量阻抗中的附加阻抗可能使距離保護拒動或誤動,風電場側尤為嚴重;受零序阻抗遠小于正負序阻抗的影響,接地阻抗元件比相間阻抗元件可耐受更大的過渡電阻,撬棒電阻投入會進一步降低相間阻抗元件的耐過渡電阻能力;受故障電流非工頻特性影響,電壓電流頻率不一致會導致測量阻抗波動,可能使保護動作時間延長,當故障位于保護范圍邊界附近時,保護可能拒動或誤動。本文提出了一種基于雙側相電流的距離保護方案和故障選相、故障類型判據(jù),該方案不受系統(tǒng)非全相運行和振蕩的影響,僅需通過已安裝的縱聯(lián)差動信道將輸電線路對側距離保護裝置測得的三相電流傳遞到本側即可,具有較高的實用性。最后,針對雙饋風電場接入對重合閘的影響,提出重合閘方案可采用檢壓檢同期改進配合方案或者自同期配合方案;當送出線路電壓互感器沒有安裝或者或者因斷線等故障退出運行時,本文也提出了一種重合閘時間計算方法。
[Abstract]:In the face of the increasingly severe problems of fossil energy depletion and environmental pollution in the world, wind power generation, as one of the important representatives of renewable energy generation, has been developed rapidly in recent years, among which doubly-fed wind turbines have high energy conversion efficiency. It is easy to realize active power and reactive power decoupling control and has been widely used in wind farms. The wind power in our country is mainly centralized large-scale grid connection, which has the characteristics of cluster development, weak power network access, long distance outgoing transmission. The unique fault characteristics of wind power bring new problems to the distance protection and reclosing of the transmission line. Therefore, it is of great significance to study the influence of doubly-fed wind farm access on transmission line relay protection and its improvement measures for improving the operational reliability of relay protection, enhancing the ability of power grid to resist faults, and ensuring the safe and stable operation of power network. In this paper, the operation principle and control strategy of doubly-fed wind turbine are studied at first. Combined with the typical grid-connected structure of doubly-fed wind farm, the detailed model and equivalent model of doubly-fed wind farm are built in DIg SILENT/Power Factory. The feasibility of model equivalence is verified under steady state and fault transient conditions. The impedance characteristic, weak feed characteristic and current non-power frequency characteristic of doubly-fed wind farm are analyzed theoretically. Based on the equivalent model of doubly-fed wind farm, the voltage and current characteristics of wind farm under different types of fault are simulated. It is proved that the theoretical analysis of the fault characteristics of wind farm is correct. Then, according to the fault characteristics of the doubly-fed wind farm, the influence of the doubly-fed wind farm access on the distance protection of the transmission line is studied. The additional impedance in the measurement impedance of the distance protection may cause the distance protection to refuse or malfunction, especially on the wind farm side. Because the zero sequence impedance is far less than the positive and negative sequence impedance, the earthing impedance element can withstand more transition resistance than the phase impedance element, and the input of the prying rod resistance will further reduce the transition resistance ability of the phase impedance element. Under the influence of non-power frequency characteristics of fault current, the inconsistent frequency of voltage and current will lead to measurement impedance fluctuation, which may prolong the protection operation time. When the fault is near the protection range boundary, the protection may refuse to operate or misoperate. In this paper, a distance protection scheme based on bilateral phase current and fault phase selection and fault type criterion are proposed. The scheme is not affected by the non-phase operation and oscillation of the system. The three-phase current measured by the distance protection device on the opposite side of the transmission line can only be transferred to the local side through the installed longitudinal differential channel, which is of high practicability. Finally, in view of the influence of doubly-fed wind farm access on reclosure, it is proposed that the reclosing scheme can be improved by checking and checking synchronously or self-synchronously. A reclosing time calculation method is also proposed when the output line voltage transformer is not installed or exits from operation due to breakage and so on.
【學位授予單位】：華北電力大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TM614;TM77
本文編號：2425710
[Abstract]:In the face of the increasingly severe problems of fossil energy depletion and environmental pollution in the world, wind power generation, as one of the important representatives of renewable energy generation, has been developed rapidly in recent years, among which doubly-fed wind turbines have high energy conversion efficiency. It is easy to realize active power and reactive power decoupling control and has been widely used in wind farms. The wind power in our country is mainly centralized large-scale grid connection, which has the characteristics of cluster development, weak power network access, long distance outgoing transmission. The unique fault characteristics of wind power bring new problems to the distance protection and reclosing of the transmission line. Therefore, it is of great significance to study the influence of doubly-fed wind farm access on transmission line relay protection and its improvement measures for improving the operational reliability of relay protection, enhancing the ability of power grid to resist faults, and ensuring the safe and stable operation of power network. In this paper, the operation principle and control strategy of doubly-fed wind turbine are studied at first. Combined with the typical grid-connected structure of doubly-fed wind farm, the detailed model and equivalent model of doubly-fed wind farm are built in DIg SILENT/Power Factory. The feasibility of model equivalence is verified under steady state and fault transient conditions. The impedance characteristic, weak feed characteristic and current non-power frequency characteristic of doubly-fed wind farm are analyzed theoretically. Based on the equivalent model of doubly-fed wind farm, the voltage and current characteristics of wind farm under different types of fault are simulated. It is proved that the theoretical analysis of the fault characteristics of wind farm is correct. Then, according to the fault characteristics of the doubly-fed wind farm, the influence of the doubly-fed wind farm access on the distance protection of the transmission line is studied. The additional impedance in the measurement impedance of the distance protection may cause the distance protection to refuse or malfunction, especially on the wind farm side. Because the zero sequence impedance is far less than the positive and negative sequence impedance, the earthing impedance element can withstand more transition resistance than the phase impedance element, and the input of the prying rod resistance will further reduce the transition resistance ability of the phase impedance element. Under the influence of non-power frequency characteristics of fault current, the inconsistent frequency of voltage and current will lead to measurement impedance fluctuation, which may prolong the protection operation time. When the fault is near the protection range boundary, the protection may refuse to operate or misoperate. In this paper, a distance protection scheme based on bilateral phase current and fault phase selection and fault type criterion are proposed. The scheme is not affected by the non-phase operation and oscillation of the system. The three-phase current measured by the distance protection device on the opposite side of the transmission line can only be transferred to the local side through the installed longitudinal differential channel, which is of high practicability. Finally, in view of the influence of doubly-fed wind farm access on reclosure, it is proposed that the reclosing scheme can be improved by checking and checking synchronously or self-synchronously. A reclosing time calculation method is also proposed when the output line voltage transformer is not installed or exits from operation due to breakage and so on.
【學位授予單位】：華北電力大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TM614;TM77
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，本文編號：2425710
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