電網故障下并網逆變器的運行仿真研究

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摘要 近些年來我國風電、太陽能等新能源發(fā)展迅猛的同時，新能源發(fā)電機組大規(guī)模地引入電網對電網的穩(wěn)定性是個嚴峻的考驗，新能源發(fā)電機組對于電力系統(tǒng)造成的影響也已經成為諸多學者和電力系統(tǒng)專家們關注的一個研究熱點。針對大規(guī)模引入新能源的現狀，當前新能源發(fā)電機組對電力系統(tǒng)影響的研究主要關注于電網電壓跌落情況下的影響。根據新能源發(fā)電機組運行規(guī)則，當電網發(fā)生外部故障時，發(fā)電機組不能立刻脫網運行，因為在電網發(fā)生故障的情況下，切除大容量的發(fā)電機組會危及整個電力系統(tǒng)，因此必須要研究在電網發(fā)生故障時，如何保證發(fā)電機組具備與電網的持續(xù)運行能力。
并網逆變器作為能量回饋的主要部件，擔負著將系統(tǒng)輸出的直流電逆變?yōu)榻涣麟婐伻腚娋W的重任，因此對其在電網故障下的運行展開深入的研究具有非常重要的意義。
本畢業(yè)設計擬對并網逆變器的控制策略展開研究，通過SIMULINK軟件模擬并網逆變器在不同電網故障下并網逆變器的運行，如三相對稱電壓跌落和單相電壓跌落等電網故障下的運行，總結出并網逆變器在電網故障下運行時各項參數的變化規(guī)律，同時根據不同電壓跌落程度對電網進行一定的無功補償，使得并網逆變器電流輸出穩(wěn)定。仿真結果表明，不同的電網故障對并網逆變器的運行都有較大的影響。因此，必須采取相應的控制策略來減小電網故障的影響，通過對電網輸送一定的無功補償可以減小電網故障的影響，甚至消除影響。

關鍵詞：并網逆變器；SVPWM；電網故障；控制策略；無功補償

The Research on the grid-connected inverter operating under grid failures
Abstract In recent years, the new energy of wind power , solar energy and other has been developing rapidly , while these new energy generators are a severe test to the stability of the grid , the impact of new energy generators for power system has leaded many scholars and the power system experts to focus on the hot research topic concerns. For large-scale introduction of new energy , the current study of the impact of new energy turbine generators for power system mainly focuses on the influence of the grid voltage drop. Based on the current rules for the operation of new energy generators, when the external grid failure occurs, generators can not grid off immediately, Because in case of the grid failure the removal of large capacity generators would endanger the entire power system. Therefore,experts must study how to ensure that generators and the grid have the ability to continue to run normally.
The grid-connected inverter is the main component of the energy feedback, which is responsible for transforming the output of the DC to the AC, so the research on the grid-connected inverter operating under grid failures is importantly significant.
I intends to study the control strategy of the grid-connected inverter in the graduation project. I will use simulink simulation software to simulate the operation of the grid-connected inverter under different grid failures , such as three-phase and single-phase voltage drop, etc. I will also summarize various parameters variation of the grid-connected inverter under different grid failures. At the same time, depending on the voltage drop on the grid , a certain degree of reactive power is poured to maintain grid electric current stability. Finally, the simulation results show that the effect of the grid failures for the grid-connected inverter operation is serious. Therefore, we must take the appropriate control strategies to reduce the impact of the grid failures. A certain degree of reactive power is poured into the grid, which can reduce the impact of the grid failures, or even eliminate the impact.
Key words: the grid-connected inverter, the grid failures, the control strategies, reactive compensation.

目錄
第一章 緒論 1
1.1 課題研究背景 1
1.2 并網逆變器國內外研究現狀 2
1.3 分布式發(fā)電系統(tǒng)并網標準 3
1.4 課題研究意義 6
1.5 主要研究內容及論文結構安排 7
第二章 并網逆變器簡介及控制原理…………………………………8
2.1 并網逆變器的技術現狀 8
2.1.1 并網逆變器的原理 8
2.1.2 并網逆變器拓撲及分類 9
2.1.3 并網逆變器的控制技術 11
2.1.3.1 并網逆變器控制目的…………………….………………11
2.1.3.2 并網逆變器控制策略………..…………………………..12
2.2 并網逆變器的數學模型 14
2.3 SVPWM的控制算法 16
2.3.1 SVPWM的基本原理 16
2.3.2 SVPWM的算法 18
2.3.2.1 3s/2r/2坐標轉換……………………….…………………...18
2.3.2.2 扇區(qū)判斷方法………………………...……………………22
2.3.2.3 扇區(qū)內矢量作用時間的算法…………………………..….22
2.3.2.4 矢量切換點算法………………………………...…………23
2.4 本章小結………………………..…………………….…………………....25
第三章 電網電壓故障下并網逆變器仿真建模與驗證 26
3.1 電網電壓跌落故障類型 26
3.2 并網逆變器仿真模型構建 28
3.3 網側正常情況下仿真結果 32
3.4 網側不同故障時仿真結果 33
3.4.1 網側三相短路故障下并網逆變器仿真 34
3.4.2 網側單相故障故障下并網逆變器仿真 35
3.4.3 網側故障時無功補償并網逆變器仿真 38
3.5 本章小結…………………………………………………………..……….39
第四章 總結與展望 40
4.1 全文總結 40
4.2 論文展望 40
致謝 41
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