本文關鍵詞： 雙饋感應風力發(fā)電機 DFIG機端相位跳變 網側變流器控制 定轉子故障電流 風電場保護策略　出處：《華北電力大學》2014年碩士論文　論文類型：學位論文

【摘要】：風力發(fā)電與傳統(tǒng)火力發(fā)電的機理不同,故障后風機電磁暫態(tài)特性發(fā)生較大變化。雙饋風電的接入,使得電網結構愈加復雜,可靠性與安全性難以得到有效的保障。因此,本文通過對電網對稱以及不對稱故障下雙饋風電機組電磁暫態(tài)特性的研究;得到雙饋風機在電網故障下定轉子電流瞬時表達式；并通過PSCAD仿真進行驗證。同時考慮到大規(guī)模雙饋風電場接入電力系統(tǒng)時對電網中傳統(tǒng)保護的影響,提出針對風電場匯流線路和風電場送出線路的改進保護策略,并通過PSCAD進行故障仿真驗證。 本文首先建立了雙饋發(fā)電系統(tǒng)不同坐標系下的暫態(tài)數學模型,重點闡述了同步旋轉軸系下雙饋感應電機的暫態(tài)模型及其常用坐標變換；推導了DFIG網側與轉子側變流器的數學模型,分析了雙饋感應風力發(fā)電機的發(fā)電特性及運行原理,并搭建了DFIG的PSCAD模型進行仿真驗證。 其次,本文在電網對稱和不對稱故障下,充分考慮DFIG機端電壓相位跳變、DFIG轉子側與網側變流器控制以及直流母線電壓的波動對故障電流的影響。利用DFIG暫態(tài)數學模型分別推導出對稱與不對稱故障下DFIG能夠反映出暫態(tài)輸出特性的DFIG定轉子電流時域表達式并通過PSCAD仿真和動模實驗驗證公式的正確性,并分析DFIG機端相位跳變以及雙饋風機網側與轉子側變流器控制對故障電流的作用機理與影響程度。 由于雙饋風電場自身的弱電源和故障特性,當風電場匯流線路或送出線路發(fā)生故障時,傳統(tǒng)保護己不能可靠動作。本文提出基于雙饋風電場故障特性的匯流線路自適應電流保護策略,基于故障穩(wěn)態(tài)量的風電場送出線路電流縱聯(lián)差動保護策略以及自適應距離保護策略。并搭建含雙饋風電場以及電網聯(lián)絡線的PSCAD模型分別對傳統(tǒng)保護和改進保護策略進行仿真驗證與分析。為大規(guī)模雙饋風電場接入電網時風電場匯流線路以及送出線路保護新原理的研究和應用提供了理論基礎。
[Abstract]:The mechanism of wind power generation is different from that of traditional thermal power generation, and the electromagnetic transient characteristics of the fan change greatly after the fault. The connection of double-fed wind power makes the power network structure more complex, and the reliability and security are difficult to be effectively guaranteed. In this paper, the electromagnetic transient characteristics of doubly-fed wind turbines under symmetrical and asymmetric faults are studied, and the transient expressions of stator and rotor currents are obtained. Considering the influence of large-scale doubly-fed wind farm on traditional protection in power network, the improved protection strategy for wind farm confluence line and wind farm output line is put forward. The fault is verified by PSCAD. In this paper, the transient mathematical model of doubly-fed induction motor in different coordinate systems is established, and the transient model of doubly-fed induction motor under synchronous rotation axis system and its common coordinate transformation are described. The mathematical models of DFIG grid-side and rotor-side converters are derived, and the generation characteristics and operation principle of doubly-fed induction wind generators are analyzed. The PSCAD model of DFIG is built for simulation verification. Secondly, in this paper, under the symmetrical and asymmetric fault of power network, The control of rotor side and grid side converter of DFIG machine and the influence of DC bus voltage fluctuation on the fault current are fully considered. Using the DFIG transient mathematical model, the DFIG energy under symmetric and asymmetric faults is derived, respectively. The time-domain expression of DFIG stator and rotor current can reflect the transient output characteristics, and the correctness of the formula is verified by PSCAD simulation and dynamic simulation. The effect mechanism and influence degree of the phase jump at the end of DFIG and the control of grid-side and rotor side converter of doubly-fed fan on the fault current are analyzed. Due to the weak power supply and fault characteristics of the doubly-fed wind farm itself, when the wind farm confluence line or the outgoing line fails, Traditional protection can not operate reliably. In this paper, an adaptive current protection strategy for confluence circuit based on fault characteristics of doubly-fed wind farm is proposed. Based on the fault steady-state value of wind farm, the current longitudinal differential protection strategy and adaptive distance protection strategy of wind farm are proposed. The PSCAD model with doubly-fed wind farm and power network tie line is built to protect the traditional protection and improve the protection strategy, respectively. It provides a theoretical basis for the research and application of the new principle of wind farm confluence line and transmission line protection when a large-scale doubly-fed wind farm is connected to the power grid.
【學位授予單位】：華北電力大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TM614

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本文編號：1555573