【摘要】：隨著各種大規(guī)�？稍偕茉唇尤腚娋W(wǎng)，傳統(tǒng)的電力裝備、結(jié)構(gòu)和運行技術(shù)等在接納超大規(guī)�？稍偕茉捶矫嬖絹碓诫y以適應(yīng)，因此必須采用新技術(shù)來滿足。而基于電壓源型換流器的直流輸電技術(shù)是解決這一問題的有效技術(shù)手段之一。為此本文針對電壓源型換流器進行了深入研究。 本文首先對換流器的數(shù)學(xué)模型進行了研究，構(gòu)建了換流器及其并聯(lián)的數(shù)學(xué)模型，并針對其數(shù)學(xué)模型設(shè)計了電流與電壓控制器。此外，利用PSCAD對雙端兩電平HVDC與雙端MMCVSC-HVDC進行了故障時的仿真。 針對電網(wǎng)含有諧波及不平衡下的并網(wǎng)電流畸變問題，本文提出了在兩相靜止坐標(biāo)系下的準(zhǔn)比例諧振與重復(fù)控制組成的復(fù)合電流控制策略。重復(fù)控制器與準(zhǔn)諧振控制相結(jié)合，既能解決重復(fù)控制無法無靜差跟隨工頻電流問題，又能消除準(zhǔn)諧振控制器的相位誤差，抑制單一控制器所存在的缺陷。此后，設(shè)計了一種基于二階廣義積分的鎖相環(huán)。理論、仿真及實驗表明：在電網(wǎng)不平衡及諧波時，復(fù)合控制策略能夠有效改善電流波形，降低并網(wǎng)電流THD；同時基于二階廣義積分的的鎖相環(huán)可以在電網(wǎng)不平衡和含諧波時對正序電壓及相位進行快速準(zhǔn)確的檢測。由于不使用陷波器進行電網(wǎng)正負序分離，，鎖相速度快。利用此鎖相環(huán)可以更好的對電流進行控制。 多換流器并聯(lián)可以提高系統(tǒng)的功率與可靠性，降低成本，但會產(chǎn)生環(huán)流。環(huán)流會增加系統(tǒng)損耗，降低系統(tǒng)效率。針對環(huán)流問題，提出了基于無差拍控制的環(huán)抑制策略，同時提出了一種虛擬換流器的概念，通過調(diào)節(jié)控制環(huán)節(jié)中SVPWM的零矢量實現(xiàn)N模塊環(huán)流的抑制。理論、仿真及實驗表明：無論給定電流及交流側(cè)濾波電感是否相等，此方法能將各個功率模塊零序環(huán)流的大小控制在同一水平，實現(xiàn)各模塊“均流”，動態(tài)相應(yīng)快，環(huán)流抑制效果較好。 最后，開發(fā)研制了一套30kW的高壓直流輸電實驗平臺，實驗平臺主要由6臺換流器組成。首先獨立設(shè)計了全部控制電路，對實驗平臺進行硬件調(diào)試，并對一次回路進行了改進。在此基礎(chǔ)上，對軟件進行編程，進行了定矢量電壓控制、電流環(huán)復(fù)合控制算法以及并聯(lián)換流器環(huán)流抑制等實驗。
[Abstract]:With a variety of large-scale renewable energy connected to the grid, the traditional power equipment, structure and operation technology are becoming more and more difficult to adapt to accept super-large scale renewable energy, so new technologies must be adopted to meet the needs. The DC transmission technology based on voltage source converter is one of the effective methods to solve this problem. Therefore, the voltage source converter is studied in this paper. In this paper, the mathematical model of the converter is studied, and the mathematical model of the converter and its parallel connection is constructed, and the current and voltage controller is designed for the mathematical model. In addition, two-terminal two-level HVDC and two-terminal MMCVSC-HVDC are simulated by PSCAD. In order to solve the problem of grid-connected current distortion with harmonics and unbalance, a compound current control strategy consisting of quasi-proportional resonance and repetitive control in two-phase stationary coordinate system is proposed in this paper. The combination of repetitive controller and quasi-resonant control can not only solve the problem that repetitive control can not only follow the power frequency current without static error, but also eliminate the phase error of the quasi-resonant controller and restrain the defects of the single controller. Then, a phase locked loop based on the second order generalized integral is designed. The theory, simulation and experiment show that the compound control strategy can effectively improve the current waveform and reduce the THD; of grid-connected current when the power network is unbalanced and harmonic. At the same time, the phase-locked loop based on the second order generalized integral can detect the positive sequence voltage and phase quickly and accurately when the power system is unbalanced and contains harmonics. Because no notch filter is used to separate the positive and negative sequence of the power system, the phase locking speed is fast. Using this PLL, the current can be controlled better. Parallel multi-converter can improve the power and reliability of the system, reduce the cost, but will produce circulation. The circulation will increase the system loss and reduce the system efficiency. Aiming at the circulation problem, a loop suppression strategy based on deadbeat control is proposed, and a concept of virtual converter is proposed, which can suppress the circulation of N module by adjusting the zero vector of SVPWM in the control link. Theoretical, simulation and experimental results show that this method can control the size of zero sequence circulation of each power module at the same level regardless of whether the current and AC side filter inductance are equal or not, and realize the "current sharing" of each module. The effect of circulation inhibition is better. Finally, a high voltage DC transmission experimental platform of 30kW is developed, which is mainly composed of 6 converters. First, all the control circuits are designed independently, the hardware of the experimental platform is debugged, and the primary circuit is improved. On this basis, the software is programmed, and experiments are carried out, such as constant vector voltage control, current loop compound control algorithm and parallel converter circulation suppression.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TM721.1

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