【摘要】：在環(huán)境污染、能源危機(jī)等多方面的壓力下,包含風(fēng)能、太陽(yáng)能等可再生能源的分布式發(fā)電成為電氣領(lǐng)域的一個(gè)研究熱點(diǎn)。分布式電源(DG)、儲(chǔ)能裝置以及負(fù)荷按照一定的拓?fù)浣Y(jié)構(gòu)可組成微電網(wǎng),因此微電網(wǎng)的發(fā)展是實(shí)現(xiàn)分布式電源大規(guī)模應(yīng)用的關(guān)鍵。微電網(wǎng)有并網(wǎng)運(yùn)行和孤島運(yùn)行兩種模式,能夠?yàn)榇箅娋W(wǎng)提供補(bǔ)充,提高區(qū)域供電可靠性和電能質(zhì)量。本文以包含風(fēng)力發(fā)電的微電網(wǎng)為研究對(duì)象,對(duì)其孤島運(yùn)行采用下垂控制策略出現(xiàn)的問(wèn)題進(jìn)行了詳細(xì)研究。針對(duì)微電網(wǎng)中線路阻抗不匹配造成的無(wú)功功率不合理分配,提出了一種基于PARK變換的線路阻抗辨識(shí)新方法,對(duì)線路阻抗值進(jìn)行了在線辨識(shí),并用得到的線路阻抗值對(duì)無(wú)功功率下垂系數(shù)進(jìn)行了修正。通過(guò)仿真和搭建的實(shí)驗(yàn)平臺(tái),驗(yàn)證了所提出方法的有效性和可行性。同時(shí),為了分析下垂系數(shù)變化時(shí)系統(tǒng)的穩(wěn)定性,建立了微電網(wǎng)小信號(hào)模型,并通過(guò)求解系統(tǒng)狀態(tài)矩陣的特征值,判斷系統(tǒng)穩(wěn)定性。其次,針對(duì)上述提到無(wú)功功率不合理分配問(wèn)題,本文提出了一種基于線路壓降補(bǔ)償?shù)母倪M(jìn)下垂控制。這種控制策略在傳統(tǒng)下垂控制基礎(chǔ)上加入線路壓降補(bǔ)償,通過(guò)平移下垂特性曲線,保證各分布式電源輸出電壓一致,實(shí)現(xiàn)無(wú)功功率的精確分配。此外,由于下垂控制存在穩(wěn)態(tài)誤差,因此在一次控制的基礎(chǔ)上加入了二次控制,使得微電網(wǎng)電壓、頻率能夠恢復(fù)至允許的范圍內(nèi)。再次,針對(duì)微電網(wǎng)中風(fēng)電-儲(chǔ)能系統(tǒng)的協(xié)調(diào)控制,本文設(shè)計(jì)了一種基于直流母線電壓自適應(yīng)調(diào)節(jié)的改進(jìn)下垂控制。在風(fēng)能或負(fù)載變化時(shí),通過(guò)動(dòng)態(tài)平移下垂特性曲線,實(shí)現(xiàn)最大程度地利用風(fēng)電,波動(dòng)引起的功率差額則由儲(chǔ)能系統(tǒng)進(jìn)行補(bǔ)償。最后,針對(duì)三相負(fù)荷不對(duì)稱造成的微電網(wǎng)交流母線電壓三相不平衡,本文在控制策略中增加了負(fù)序電壓抑制。利用Matlab/Simulink仿真對(duì)比了采用電壓電流雙閉環(huán)控制和所設(shè)計(jì)的正負(fù)序電壓電流控制兩種方法,證明了所設(shè)計(jì)的方法可有效地降低交流母線的不平衡度。
[Abstract]:Under the pressure of environmental pollution and energy crisis, distributed power generation, which includes renewable energy such as wind and solar energy, has become a research hotspot in electrical field. The (DG), energy storage device and load of distributed power supply can form microgrid according to a certain topology, so the development of microgrid is the key to realize the large-scale application of distributed power supply. There are two modes of micro-grid operation: grid-connected operation and island operation, which can supplement the large power grid and improve the reliability and power quality of regional power supply. In this paper, the problems of sag control strategy used in island operation of micro-grid including wind power generation are studied in detail. In view of the unreasonable allocation of reactive power caused by the mismatch of line impedance in microgrid, a new method of line impedance identification based on PARK transform is proposed, and on-line identification of line impedance is carried out. The sag coefficient of reactive power is modified by using the line impedance value obtained. The validity and feasibility of the proposed method are verified by simulation and experimental platform. At the same time, in order to analyze the stability of the system when the droop coefficient changes, the small signal model of the microgrid is established, and the stability of the system is judged by solving the eigenvalues of the state matrix of the system. Secondly, an improved droop control based on line voltage drop compensation is proposed to solve the problem of unreasonable distribution of reactive power. This control strategy adds line voltage drop compensation on the basis of traditional droop control. By translating droop characteristic curve, the output voltage of each distributed power supply can be guaranteed to be consistent and the reactive power distribution can be realized accurately. In addition, due to the steady-state error of droop control, the secondary control is added on the basis of primary control, so that the voltage and frequency of microgrid can be restored to the allowable range. Thirdly, for the coordinated control of wind power and energy storage system in microgrid, an improved droop control based on DC bus voltage adaptive regulation is designed in this paper. When the wind energy or load changes, the maximum utilization of wind power can be achieved by means of the dynamic translation droop curve, and the power difference caused by the fluctuation is compensated by the energy storage system. Finally, in view of the three-phase unbalanced AC bus voltage caused by three-phase load asymmetry, negative sequence voltage suppression is added to the control strategy in this paper. Two methods of voltage-current double closed-loop control and positive-negative sequence voltage-current control are compared by Matlab/Simulink simulation. It is proved that the designed method can effectively reduce the unbalance degree of AC bus.
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TM727

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