【摘要】：三相PWM整流器作為新一代“綠色”變流裝置，因其高功率因數(shù)、正弦波電流控制和AC/DC變換可控等優(yōu)點(diǎn)受到了廣泛的關(guān)注與發(fā)展，，在現(xiàn)代電能轉(zhuǎn)換裝置中得到廣泛的應(yīng)用。然而，在實(shí)際的電網(wǎng)當(dāng)中，由于大量非線性負(fù)載以及各相間負(fù)載不平衡等原因，導(dǎo)致三相電網(wǎng)電壓不平衡現(xiàn)象普遍存在。電網(wǎng)三相電壓的不平衡將會(huì)給三相PWM整流器的性能帶來較為嚴(yán)重的負(fù)面影響，因此，電網(wǎng)不平衡條件下，如何改進(jìn)三相PWM整流器的控制方法以消除不平衡帶來的負(fù)面影響成為一個(gè)亟待解決的問題。 首先，本文基于基爾霍夫電壓電流定律以及瞬時(shí)功率理論推導(dǎo)出三相PWM整流器在電網(wǎng)不平衡時(shí)的瞬時(shí)功率模型，以此為基礎(chǔ)，分析了電網(wǎng)不平衡時(shí)系統(tǒng)二次功率脈動(dòng)的成因，并對(duì)所能達(dá)到的最佳控制效果進(jìn)行了討論。 其次，在存在諧波的情況下，傳統(tǒng)正負(fù)序分離方法將不再有效，本文提出了一種基于改進(jìn)最小二乘法的正負(fù)序分離方法。通過分離計(jì)算過程中的時(shí)變部分與常數(shù)部分以及分解矩陣求逆運(yùn)算等方法，降低了算法的實(shí)時(shí)計(jì)算量以及對(duì)舍入誤差的敏感程度。在此基礎(chǔ)上，結(jié)合對(duì)稱分量法，推導(dǎo)出正負(fù)序分量的分離算法。該方法在保證實(shí)時(shí)提取速度基礎(chǔ)上，增強(qiáng)了對(duì)諧波干擾的抑制能力。 然后，在直接功率控制基礎(chǔ)上，為了提高系統(tǒng)魯棒性，提出了改進(jìn)的電網(wǎng)不平衡時(shí)三相PWM整流器的不平衡控制策略。該策略考慮有功和無功二次脈動(dòng)對(duì)系統(tǒng)帶來的影響，并通過引入功率給定修正環(huán)節(jié)對(duì)其進(jìn)行了消除。結(jié)構(gòu)上，采用基礎(chǔ)控制器加抗擾控制器的結(jié)構(gòu)，基礎(chǔ)控制器以保證控制系統(tǒng)基本性能為目的，通過逆系統(tǒng)方法對(duì)原系統(tǒng)解耦與線性化之后建立；抗擾控制器以增強(qiáng)系統(tǒng)魯棒性為目的，采用自適應(yīng)滑�？刂扑惴āＴ摽刂撇呗钥梢杂行У慕鉀Q由于電網(wǎng)電壓不平衡對(duì)三相PWM整流器的控制帶來的電流畸變，功率脈動(dòng)以及功率因數(shù)降低等問題。 通過Simulink仿真以及基于dSPACE的半實(shí)物驗(yàn)證實(shí)驗(yàn)證明，本文所提出的電網(wǎng)不平衡時(shí)三相PWM整流器的控制策略可以有效的解決電網(wǎng)不平衡對(duì)系統(tǒng)帶來的各種負(fù)面影響，可以較為精確地達(dá)到所設(shè)計(jì)的控制目標(biāo)。具有動(dòng)態(tài)響應(yīng)快，魯棒性好等優(yōu)點(diǎn)。
[Abstract]:As a new generation of "green" converter, three-phase PWM rectifier has been widely concerned and developed for its advantages of high power factor, sinusoidal current control and AC/DC conversion controllability, and has been widely used in modern power conversion devices. However, because of a large number of nonlinear loads and load imbalance between phases, the voltage imbalance of three-phase power network is widespread in the actual power network. The unbalance of three-phase voltage will bring serious negative effects to the performance of three-phase PWM rectifier. How to improve the control method of three-phase PWM rectifier to eliminate the negative effects caused by imbalance has become an urgent problem. Firstly, based on Kirchhoff's law of voltage and current and instantaneous power theory, the instantaneous power model of three-phase PWM rectifier in unbalanced power network is derived. Based on this model, the cause of secondary power pulsation is analyzed. The optimal control effect is discussed. Secondly, in the presence of harmonics, the traditional positive and negative sequence separation method will no longer be effective. In this paper, an improved least square method for positive and negative sequence separation is proposed. By separating the time-varying part from the constant part and the factorization matrix inversion, the real-time computation and the sensitivity to rounding error of the algorithm are reduced. On this basis, combined with the symmetric component method, the separation algorithm of positive and negative ordered components is derived. This method enhances the ability to suppress harmonic interference on the basis of guaranteeing real-time extraction speed. Then, on the basis of direct power control, in order to improve system robustness, an improved unbalanced control strategy for three-phase PWM rectifier is proposed. The effect of active and reactive power secondary pulsation on the system is considered in this strategy, and it is eliminated by introducing a given power correction link. In structure, the structure of the basic controller plus disturbance rejection controller is adopted. The basic controller is established after decoupling and linearizing the original system by inverse system method to ensure the basic performance of the control system. In order to enhance the robustness of the system, the disturbance rejection controller adopts an adaptive sliding mode control algorithm. This control strategy can effectively solve the problems of current distortion, power pulsation and power factor reduction caused by the control of three-phase PWM rectifier due to the unbalanced voltage of the power network. Through the Simulink simulation and the hardware-in-the-loop verification experiment based on dSPACE, it is proved that the control strategy of the three-phase PWM rectifier proposed in this paper can effectively solve the negative effects of the unbalanced power grid on the system. The designed control objectives can be achieved more accurately. It has the advantages of fast dynamic response and good robustness.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TM461

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