【摘要】：雙饋感應(yīng)發(fā)電機(jī)(Doubly Fed Induction Generator，DFIG)以其靈活的控制性能，在風(fēng)力發(fā)電中應(yīng)用廣泛。電網(wǎng)發(fā)生短路時DFIG機(jī)端電壓下降，在定子繞組產(chǎn)生沖擊電流，對于大部分商用DFIG機(jī)組，須在轉(zhuǎn)子側(cè)接入合適的撬棒電阻，以保護(hù)DFIG和實現(xiàn)低電壓穿越運(yùn)行。短路電流計算是電網(wǎng)規(guī)劃和保護(hù)的基礎(chǔ)，短路故障將會對電網(wǎng)及設(shè)備產(chǎn)生沖擊，特別是電氣設(shè)備動穩(wěn)定性校驗和確保含DFIG電網(wǎng)中斷路器遮斷容量的合理配置時，都須對電網(wǎng)故障后DFIG短路電流峰值進(jìn)行估算，因此準(zhǔn)確地計算出短路電流的峰值尤為重要。本文主要內(nèi)容如下： ①根據(jù)DFIG矢量模型，推導(dǎo)撬棒保護(hù)動作前后的DFIG定轉(zhuǎn)子電流解析式。當(dāng)配網(wǎng)故障后撬棒保護(hù)未動作時，考慮轉(zhuǎn)子側(cè)變流器控制對轉(zhuǎn)子電流的調(diào)節(jié)作用，利用轉(zhuǎn)子電壓和轉(zhuǎn)子變流器輸出電壓指令方程，求解轉(zhuǎn)子電流二階微分方程，，推導(dǎo)撬棒保護(hù)未動作時DFIG的三相短路電流解析式；而撬棒保護(hù)動作后，考慮撬棒電阻計算定子磁鏈直流分量，提出將DFIG定子磁鏈直流分量歸算至轉(zhuǎn)子側(cè)形成靜態(tài)等值電路，以此推導(dǎo)撬棒保護(hù)動作時DFIG的三相短路電流解析式。 ②基于DFIG定子三相短路電流時域表達(dá)式，提出DFIG接入配電網(wǎng)的三相短路電流峰值評估方法。根據(jù)撬棒保護(hù)動作前的轉(zhuǎn)子電流表達(dá)式，研究不同功率控制下的轉(zhuǎn)子電流峰值對撬棒保護(hù)的影響，提出撬棒判別依據(jù)；針對撬棒動作后分析近端和遠(yuǎn)端故障時不同撬棒電阻對短路電流暫態(tài)直流分量、暫態(tài)周期分量和強(qiáng)制分量的影響，利用DFIG轉(zhuǎn)子運(yùn)動方程，提出計及轉(zhuǎn)速變化的DFIG三相短路電流峰值評估方法，由此來確定DFIG三相短路電流峰值的出現(xiàn)時刻。 ③在MATLAB/Simulink仿真軟件平臺中建立DFIG接入配電網(wǎng)的電磁暫態(tài)仿真模型，驗證本文提出的評估方法。分析DFIG三相短路故障暫態(tài)特性，研究不同機(jī)組容量以及不同故障節(jié)點(diǎn)時的DFIG三相短路電流，并對本文所提方法的計算值與仿真結(jié)果進(jìn)行對比分析，驗證所提出的DFIG接入配電網(wǎng)的三相短路電流峰值評估方法的正確性。
[Abstract]:Doubly-fed induction generator (DFIG) is widely used in wind power generation due to its flexible control performance. For most commercial DFIG units, appropriate crowbar resistance should be connected to the rotor side to protect DFIG and realize low voltage traversing operation. Short circuit current calculation is the basis of power network planning and protection. Short circuit fault will impact the power network and equipment, especially when checking the dynamic stability of electrical equipment and ensuring the reasonable configuration of circuit breaker interrupting capacity in DFIG power network. It is necessary to estimate the peak value of DFIG short-circuit current after fault, so it is very important to calculate the peak value of short-circuit current accurately. The main contents of this paper are as follows: 1 according to the DFIG vector model, the analytical formula of DFIG stator and rotor current before and after crowbar protection is derived. When the bar protection does not work after the fault of the distribution network, considering the regulating effect of the rotor side converter control on the rotor current, the second order differential equation of rotor current is solved by using the rotor voltage and the output voltage instruction equation of the rotor converter. The three-phase short circuit current analytical formula of DFIG is deduced when the rod protection is not in operation, and the DC component of stator flux is calculated by considering the crowbar resistance, and the static equivalent circuit is formed when the DC component of DFIG stator flux is reduced to the rotor side. Based on the time-domain expression of three-phase short-circuit current of DFIG stator, a method for evaluating the peak value of three-phase short-circuit current of DFIG connected to distribution network is proposed. According to the expression of rotor current before crowbar protection, the influence of rotor current peak value under different power control on crowbar protection is studied, and the discriminant basis of crowbar is put forward. Based on the analysis of the influence of different crowbar resistance on the transient DC component, transient periodic component and forced component of short circuit current, the DFIG rotor motion equation is used to analyze the influence of different bar resistance on the transient DC component, transient periodic component and forced component of short circuit current. A method of evaluating the peak value of DFIG three-phase short-circuit current considering the variation of rotational speed is proposed to determine the peak time of DFIG three-phase short-circuit current. 3 the electromagnetic transient simulation model of DFIG connecting to distribution network is established in MATLAB / Simulink simulation software platform. Verify the evaluation method proposed in this paper. The transient characteristics of DFIG three-phase short-circuit fault are analyzed, and the DFIG three-phase short-circuit current with different unit capacity and different fault nodes is studied, and the calculated value of the proposed method is compared with the simulation results. The correctness of the proposed method for evaluating the peak value of three phase short circuit current in DFIG distribution network is verified.
【學(xué)位授予單位】：重慶大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TM31

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