【摘要】：因全球工業(yè)經(jīng)濟(jì)的快速發(fā)展,地球上的一次能源隨之減少,能源危機(jī)和環(huán)境污染問(wèn)題愈加嚴(yán)峻。作為新能源之一的太陽(yáng)能,因具有獨(dú)特的優(yōu)勢(shì)成為理想的替代能源,成為新能源開(kāi)發(fā)中研究的熱點(diǎn)之一。隨著光伏系統(tǒng)的不斷發(fā)展,光伏并網(wǎng)逐漸普遍,而并網(wǎng)對(duì)電力系統(tǒng)造成的不利影響也越加明顯。無(wú)功補(bǔ)償作為改善光伏系統(tǒng)并網(wǎng)電能質(zhì)量,提高系統(tǒng)穩(wěn)定運(yùn)行的重要措施,廣泛的應(yīng)用于光伏系統(tǒng)中。對(duì)光伏系統(tǒng)中無(wú)功補(bǔ)償裝置的要求是,當(dāng)電網(wǎng)發(fā)生故障時(shí),光伏仍保持并網(wǎng)運(yùn)行,不從電網(wǎng)吸收功率而是向系統(tǒng)輸入無(wú)功功率來(lái)幫助系統(tǒng)恢復(fù)。因?yàn)殪o止無(wú)功發(fā)生器的優(yōu)良性能,所以已經(jīng)成為近些年來(lái)無(wú)功補(bǔ)償裝置的主要發(fā)展方向。以三相光伏并網(wǎng)發(fā)電系統(tǒng)為整體,分析了光伏電池的特性,并對(duì)最大功率跟蹤點(diǎn)和并網(wǎng)逆變控制技術(shù)進(jìn)行了詳細(xì)介紹。在MATLAB中建立了仿真模型,搭建了系統(tǒng)的各個(gè)子模塊模型,為分析靜止無(wú)功發(fā)生器在光伏系統(tǒng)正常運(yùn)行和故障時(shí)的補(bǔ)償效果的仿真打下基礎(chǔ)。另一方面,以靜止無(wú)功發(fā)生器(SVG)為整體。對(duì)其工作原理進(jìn)行闡明分析,并詳細(xì)的分析了對(duì)于無(wú)功電流檢測(cè)和控制策略的各種方法。通過(guò)比較直接電流和間接電流控制,對(duì)于控制系統(tǒng)的設(shè)計(jì),采用了兩相旋轉(zhuǎn)dq坐標(biāo)數(shù)學(xué)模型。在此基礎(chǔ)上,對(duì)電壓電流進(jìn)行了前饋解耦,以便于完成有功無(wú)功的單獨(dú)控制。因此采用了基于電壓電流雙環(huán)負(fù)反饋控制的結(jié)構(gòu)形式,以達(dá)到穩(wěn)定并網(wǎng)點(diǎn)電壓和直流側(cè)電壓為控制目的的目標(biāo)。因?yàn)榘l(fā)生三相短路故障時(shí),傳統(tǒng)的PI控制其相應(yīng)參數(shù)無(wú)法自行改變,而作出相應(yīng)的有效調(diào)節(jié)。所以引入模糊控制理論對(duì)PI調(diào)節(jié)進(jìn)行改進(jìn),提高三相短路時(shí)SVG無(wú)功補(bǔ)償?shù)目刂菩Ч�。最終的控制方法兼具模糊控制和PI控制的優(yōu)點(diǎn),可以根據(jù)不同狀態(tài)下負(fù)載的變化而實(shí)時(shí)發(fā)出或吸收無(wú)功功率。最后在MATLAB中搭建了含有光伏發(fā)電系統(tǒng)的電網(wǎng)整體仿真模型,分別對(duì)不同性質(zhì)的負(fù)載進(jìn)行無(wú)功補(bǔ)償前后效果的仿真對(duì)比分析。再對(duì)系統(tǒng)中突然增加負(fù)載的情況進(jìn)行仿真,驗(yàn)證模糊PI控制的實(shí)時(shí)性和有效性。通過(guò)對(duì)仿真結(jié)果的對(duì)比分析證明了靜止無(wú)功發(fā)生器良好的動(dòng)態(tài)補(bǔ)償性能,可以有效提高光伏系統(tǒng)的功率因數(shù),同時(shí)對(duì)系統(tǒng)節(jié)點(diǎn)電壓起到穩(wěn)定的作用。
[Abstract]:With the rapid development of the global industrial economy, the primary energy on the earth has been reduced, and the energy crisis and environmental pollution have become more and more serious. As one of the new energy sources, solar energy has become an ideal alternative energy because of its unique advantages, and has become one of the hot spots in the development of new energy. With the continuous development of photovoltaic system, grid-connected photovoltaic system is becoming more and more common, and the negative impact of grid-connected power system is becoming more and more obvious. Reactive power compensation is widely used in photovoltaic system as an important measure to improve the power quality of grid-connected photovoltaic system and to improve the stable operation of the system. The requirement of the reactive power compensator in the photovoltaic system is that when the power grid fails, the photovoltaic system will still run grid-connected, and instead of absorbing the power from the grid, it will input the reactive power to the system to help the system recover. Because of the excellent performance of static var generator, it has become the main development direction of reactive power compensator in recent years. Taking the three-phase photovoltaic grid-connected generation system as a whole, the characteristics of photovoltaic cells are analyzed, and the maximum power tracking point and grid-connected inverter control technology are introduced in detail. The simulation model is established in MATLAB, and each sub-module model of the system is set up, which lays a foundation for the simulation of the compensation effect of the static Var Generator in the normal operation and failure of the photovoltaic system. On the other hand, the static Var Generator (SVG) is taken as a whole. The principle of reactive current detection and control strategy are analyzed in detail. By comparing direct and indirect current control, a two-phase rotating dq coordinate mathematical model is used for the design of the control system. On this basis, feedforward decoupling of voltage and current is carried out to facilitate the control of active power and reactive power. Therefore, the structure of double loop negative feedback control based on voltage and current is adopted to achieve the goal of stable node voltage and DC side voltage. Because the traditional PI control parameters can not be changed by themselves when the three-phase short circuit fault occurs, the corresponding effective adjustment can be made. So the fuzzy control theory is introduced to improve the PI regulation to improve the control effect of SVG reactive power compensation under three phase short circuit. The final control method has the advantages of both fuzzy control and PI control. It can emit or absorb reactive power in real time according to the variation of load in different states. Finally, the whole simulation model of power grid with photovoltaic generation system is built in MATLAB, and the simulation results before and after reactive power compensation of different properties of load are compared and analyzed respectively. The real time and effectiveness of fuzzy PI control are verified by simulation of the sudden increase of load in the system. The simulation results show that the static Var generator has good dynamic compensation performance, which can effectively improve the power factor of photovoltaic system and stabilize the node voltage of the system.
【學(xué)位授予單位】：東北農(nóng)業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：TM615;TM761.12
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本文編號(hào)：2393697