【摘要】：在低壓配電網(wǎng)中,系統(tǒng)用戶側(cè)大多都是單相負荷,且用電具有不同時性,配電系統(tǒng)極易出現(xiàn)三相不平衡問題,對電能質(zhì)量產(chǎn)生了嚴重影響。目前針對不平衡補償?shù)挠性囱b置的研究大多為三相三線制,只能消除負序電流,而不治理零序電流。因此對三相四線制負載不平衡補償裝置研究,對改善電能質(zhì)量及配電網(wǎng)的安全穩(wěn)定運行有重大現(xiàn)實意義。本文以三相四線制負載不平衡有源調(diào)節(jié)裝置為研究對象,針對不平衡電流檢測、電網(wǎng)同步算法、調(diào)制算法、電流跟蹤控制算法等關鍵問題進行了研究。針對三相四線制負載不平衡的特點,實現(xiàn)補償負序電流的同時也能補償中性線上的零序電流,選擇了四橋臂的變流器作為裝置的拓撲結構,濾波器使用四支路的LCL濾波器,并對此模型進行了數(shù)學建模和分析,給出了LCL濾波器參數(shù)的設計方法。為了解決負載不平衡電流解耦問題,本文從抗干擾能力的角度分析比較了陷波器法、延時信號法和基于二階廣義積分器的解耦法三種方法,證明了基于二階廣義積分的解耦法抗干擾能力較強、穩(wěn)定性較好,適用于補償裝置。仿真結果表明該方法能實現(xiàn)負載不平衡電流基波正序、負序和零序分量的快速零誤差解耦。針對電網(wǎng)不平衡工況下傳統(tǒng)鎖相環(huán)性能不佳的問題,本文從鎖相精度和動態(tài)響應速度的角度研究了基于雙同步坐標系解耦的電網(wǎng)同步算法和基于二階廣義積分的電網(wǎng)同步算法。針對系統(tǒng)動態(tài)響應速度慢的缺點,本文進行了改進,即SOGI-αβ混合電網(wǎng)同步算法。分析了鎖相環(huán)的線性模型及系統(tǒng)的穩(wěn)定性,并對系統(tǒng)進行了參數(shù)設計。仿真和試驗結果表明改進的算法,能快速準確鎖定電網(wǎng)電壓相位,且有較強的抗干擾能力。針對四橋臂變流器有開關狀態(tài)多,電壓調(diào)制算法復雜的特點,本文設計了三維空間矢量脈寬調(diào)制算法,仿真結果表明該算法調(diào)制得到的輸出電壓與參考電壓一致。補償裝置的控制策略是本文的研究重點,為了提高控制系統(tǒng)的性能,本文在滿足系統(tǒng)穩(wěn)定性前提下,針對傳統(tǒng)重復控制器動態(tài)響應速度慢的缺點提出改進方案,在傳統(tǒng)重復控制器上加了比例控制器,經(jīng)過改進后的重復控制器有很好的指令電流跟蹤能力,可以在含有諧波的指令信號中準確的跟蹤基波信號。此外還設計了電壓環(huán)控制器參數(shù),直流母線電容參數(shù)及系統(tǒng)的硬件。最后通過仿真和實驗驗證了系統(tǒng)的正確性和有效性。
[Abstract]:In the low-voltage distribution network, most of the system users are single-phase load, and the power consumption is different, distribution system is easy to appear three-phase imbalance problem, which has a serious impact on the power quality. At present, most of the researches on unbalanced compensator are three-phase three-wire system, which can only eliminate the negative sequence current, but not the zero sequence current. Therefore, it is of great practical significance to study the three-phase four-wire load imbalance compensation device to improve the power quality and the safe and stable operation of the distribution network. In this paper, the three-phase four-wire load unbalanced active regulating device is taken as the research object. The key problems such as unbalanced current detection, power grid synchronization algorithm, modulation algorithm and current tracking control algorithm are studied. In view of the unbalanced load of three-phase four-wire system, the negative sequence current can be compensated and the zero sequence current on the neutral line can be compensated. The converter of the four-arm is chosen as the topology of the device. The filter uses four-branch LCL filter. The model is modeled and analyzed, and the design method of LCL filter parameters is given. In order to solve the problem of load unbalance current decoupling, this paper analyzes and compares three methods: notch method, delay signal method and decoupling method based on second-order generalized integrator from the point of view of anti-jamming ability. It is proved that the decoupling method based on the second order generalized integral has strong anti-interference ability and good stability. It is suitable for the compensator. The simulation results show that the proposed method can decouple the zero error of the fundamental sequence, the negative sequence and the zero sequence component of the load unbalance current. In order to solve the problem of poor performance of traditional phase-locked loop (PLL) under unbalanced condition, this paper studies the synchronization algorithm based on the decoupling of double synchronous coordinate system and the power system synchronization algorithm based on second-order generalized integral from the point of view of phase-locked precision and dynamic response speed. Aiming at the shortcoming of slow dynamic response, this paper improves the synchronization algorithm of SOGI- 偽 尾 hybrid power system. The linear model of PLL and the stability of the system are analyzed, and the system parameters are designed. The simulation and experimental results show that the improved algorithm can lock the voltage phase of the power system quickly and accurately, and has strong anti-interference ability. In view of the multi-switching state and complex voltage modulation algorithm of the four-arm converter, a three-dimension space vector pulse width modulation algorithm is designed in this paper. The simulation results show that the output voltage obtained by the algorithm is consistent with the reference voltage. The control strategy of the compensator is the focus of this paper. In order to improve the performance of the control system, in order to improve the performance of the control system, this paper, on the premise of satisfying the stability of the system, puts forward an improved scheme aiming at the shortcoming of the slow dynamic response speed of the traditional repetitive controller. A proportional controller is added to the traditional repetitive controller. The improved repetitive controller has a good command current tracking ability and can accurately track the fundamental signal in the instruction signal containing harmonics. In addition, the parameters of voltage loop controller, DC bus capacitance and the hardware of the system are also designed. Finally, the correctness and validity of the system are verified by simulation and experiment.
【學位授予單位】：中國礦業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TM761.12

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