【摘要】：PWM整流器具有功率因數(shù)可控、網(wǎng)側(cè)電流畸變率小和能量能夠雙向流動等特點,在交流電氣傳動、有源電力濾波及新能源并網(wǎng)發(fā)電等領(lǐng)域得到了廣泛的應(yīng)用。在實際應(yīng)用中,由于三相負荷不對稱等原因會導(dǎo)致電網(wǎng)不平衡。此時,若仍然采用電網(wǎng)平衡時設(shè)計的PWM整流器控制策略,將會導(dǎo)致網(wǎng)側(cè)電流畸變和直流側(cè)電壓波動,嚴重時會影響電力設(shè)備的正常運行,甚至損壞設(shè)備。為此,本文對電網(wǎng)不平衡情況下的PWM整流器控制策略進行了深入研究。首先,根據(jù)基爾霍夫定律和瞬時功率理論分別建立了電網(wǎng)不平衡情況下三相PWM整流器的電壓電流數(shù)學(xué)模型和瞬時功率數(shù)學(xué)模型。通過對比發(fā)現(xiàn),電網(wǎng)不平衡情況下的PWM整流器數(shù)學(xué)模型同樣適用于電網(wǎng)平衡情況下,在電網(wǎng)狀態(tài)發(fā)生變化時,無需考慮系統(tǒng)模型變化可能造成的問題。其次,在三相PWM整流器數(shù)學(xué)模型的基礎(chǔ)上,深入地研究了電網(wǎng)不平衡情況下PWM整流器雙電流控制策略和電網(wǎng)不平衡情況下PWM整流器滑模變結(jié)構(gòu)直接功率控制策略。針對以上兩種控制策略存在的問題,本文提出了一種電網(wǎng)不平衡情況下PWM整流器無差拍預(yù)測直接功率控制策略。為提高系統(tǒng)動態(tài)性能,本文設(shè)計了全數(shù)字化的無差拍控制器作為功率內(nèi)環(huán)控制器,實現(xiàn)了兩相靜止坐標(biāo)系下瞬時功率對給定功率的快速跟蹤控制;為優(yōu)化無差拍控制器的性能,分析了時間延遲對控制器的影響并提出了相應(yīng)的補償方案。與此同時,通過設(shè)置三個控制目標(biāo)來對系統(tǒng)進行控制,即抑制負序電流、抑制有功功率波動、抑制無功功率波動。為簡化控制結(jié)構(gòu)、減少運算量,通過采用一種新型瞬時功率分析方法,無需正負序分量提取就可針對設(shè)置的三個控制目標(biāo)進行不同的功率項補償,進而實現(xiàn)控制目標(biāo)。仿真驗證了該策略的有效性。最后,搭建了電網(wǎng)不平衡情況下PWM整流器實驗平臺,對所提控制策略進行了相關(guān)實驗。通過實驗結(jié)果分析,進一步驗證了該策略的有效性。
[Abstract]:PWM rectifier has been widely used in AC electric drive, active power filtering and new energy grid-connected power generation because of its controllable power factor, low current distortion rate on the grid side and two-way flow of energy. In practical application, the imbalance of power grid will be caused by the asymmetry of three-phase load. At this time, if the PWM rectifier control strategy designed when the power grid is balanced, it will lead to the current distortion on the network side and the voltage fluctuation on the DC side, which will seriously affect the normal operation of the power equipment and even damage the equipment. Therefore, the control strategy of PWM rectifier under unbalanced power grid is deeply studied in this paper. Firstly, according to Kirchhoff's law and instantaneous power theory, the mathematical models of voltage and current and instantaneous power of three-phase PWM rectifier under unbalanced power grid are established respectively. Through comparison, it is found that the mathematical model of PWM rectifier under the condition of power grid imbalance is also suitable for the case of power grid balance, and the possible problems caused by the change of system model do not need to be considered when the power grid state changes. Secondly, on the basis of the mathematical model of three-phase PWM rectifier, the double current control strategy of PWM rectifier under unbalanced power grid and the direct power control strategy of sliding mode variable structure of PWM rectifier under unbalanced power grid are deeply studied. In order to solve the problems of the above two control strategies, a deadbeat predictive direct power control strategy for PWM rectifier under unbalanced power grid is proposed in this paper. In order to improve the dynamic performance of the system, a fully digital deadbeat controller is designed as the power inner loop controller to realize the fast tracking control of instantaneous power to a given power in a two-phase static coordinate system. In order to optimize the performance of the deadbeat controller, the influence of time delay on the controller is analyzed and the corresponding compensation scheme is proposed. At the same time, the system is controlled by setting three control objectives, that is, suppressing negative sequence current, suppressing active power fluctuation and suppressing reactive power fluctuation. In order to simplify the control structure and reduce the amount of computation, a new instantaneous power analysis method is adopted, which can compensate the three control targets with different power terms without the extraction of positive and negative sequence components, and then realize the control objectives. The effectiveness of the strategy is verified by simulation. Finally, the experimental platform of PWM rectifier under the condition of unbalanced power grid is built, and the related experiments of the proposed control strategy are carried out. The effectiveness of the strategy is further verified by the analysis of experimental results.
【學(xué)位授予單位】：中國礦業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TM461

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