電網(wǎng)故障情況下三相光伏三電平逆變器的控制技術研究
發(fā)布時間：2018-10-10 11:21
【摘要】：如今隨著新能源的發(fā)展，大量光伏發(fā)電系統(tǒng)并網(wǎng)連接。由于線路短路等電網(wǎng)故障造成的電網(wǎng)電壓跌落使得并網(wǎng)控制策略出現(xiàn)了很多問題亟待解決，這就需要并網(wǎng)光伏系統(tǒng)在電網(wǎng)故障期間需要滿足許多諸如逆變器快速準確的電網(wǎng)同步技術、不平衡電流控制、無功支撐、功率因數(shù)矯正和電網(wǎng)故障穿越等并網(wǎng)標準。然而，公共耦合點非線性負載和電網(wǎng)中常見的兩相短路和單相短路都會導致電網(wǎng)電壓的不平衡和非正弦畸變，使得逆變器同步電網(wǎng)的相位、瞬時有功功率和無功功率、直流側(cè)電壓、并網(wǎng)電流和電壓的正負序分量都會產(chǎn)生影響逆變器性能的二倍頻振蕩。 本文在三電平中點鉗位式逆變器拓撲基礎上，提供了很多可以解決電網(wǎng)故障情況下并網(wǎng)變量振蕩和電網(wǎng)故障穿越能力等問題的控制方案。首先，為了解決三電平中點鉗位式拓撲在實際運行中易造成中點電位不平衡的問題，文中采用了基于電容電荷守恒原理來改變逆變器開關狀態(tài)的直流側(cè)中點電位控制。其次，為了解決電網(wǎng)發(fā)生不對稱故障時的電網(wǎng)同步問題，本文采用了一種基于新型解耦雙同步參考坐標系鎖相環(huán)的正序電壓相位檢測技術，這種方法可以完全消除普通同步參考坐標系鎖相環(huán)的相位檢測誤差，并且能準確分離出不平衡電網(wǎng)電壓的正序和負序分量。在設計電網(wǎng)不對稱故障條件下的電流控制策略時，本文采用了一種新的基于交叉解耦雙同步參考坐標系下PI控制電流環(huán)的正負序并網(wǎng)電流控制方案，這種方案可以抵消由電流正負序分量造成的電流分量上的二倍頻振蕩。然而，在電網(wǎng)發(fā)生故障期間，光伏系統(tǒng)為了把光伏電池產(chǎn)生的功率全部傳輸給電網(wǎng)必然會增大并網(wǎng)電流從而導致由過流引起的光伏并網(wǎng)系統(tǒng)解列。為了解決這個問題，本文采用了基于正負序控制的帶電流限制的功率控制算法與光伏電池定功率跟蹤控制方案相結(jié)合的控制策略。最后，，本文推導了一系列計算瞬時有功功率和無功功率中功率振蕩的方案，可以根據(jù)實際電網(wǎng)故障情況來選擇最合適的方案來消除功率振蕩。 本文基于DSP與FPGA控制系統(tǒng)，在帶LCL濾波的三電平中點鉗位式并網(wǎng)逆變器實驗平臺上驗證了部分理論與實驗研究，實驗結(jié)果驗證了理論的正確性。
[Abstract]:Now with the development of new energy, a large number of photovoltaic power systems connected to the grid. Because of the voltage drop caused by circuit short circuit and other network faults, there are many problems to be solved urgently in the grid-connected control strategy. Therefore, grid-connected photovoltaic systems need to meet many grid-connected standards such as inverter fast and accurate synchronization technology, unbalanced current control, reactive power support, power factor correction and fault traversing. However, the common coupling point nonlinear load and the common two-phase and single-phase short-circuit in the power network will lead to the unbalanced and non-sinusoidal voltage of the power network, which makes the inverter synchronize the phase, instantaneous active power and reactive power. The positive and negative sequence components of DC side voltage, grid-connected current and voltage will produce double frequency oscillation which affects the performance of inverter. Based on the topology of three-level neutral-point clamped inverter, this paper provides many control schemes which can solve the problems of grid-connected variable oscillation and power network fault traversing ability. Firstly, in order to solve the problem that the three-level neutral-point clamping topology is prone to cause the neutral point potential imbalance in practical operation, the DC side neutral point potential control based on the principle of capacitance charge conservation is adopted to change the switching state of the inverter. Secondly, in order to solve the problem of power network synchronization in the event of asymmetric fault, this paper uses a novel decoupled double-synchronous reference coordinate system phase-locked loop to detect the positive sequence voltage and phase. This method can completely eliminate the phase detection error of the common synchronous reference coordinate PLL and can accurately separate the positive and negative sequence components of unbalanced grid voltage. In the design of current control strategy under asymmetrical fault condition, a new current control scheme based on PI control current loop in cross-decoupled double-synchronous reference coordinate system is proposed in this paper. This scheme can counteract the double frequency oscillation on the current component caused by the positive and negative sequence components of the current. However, in order to transmit all the power generated by photovoltaic cells to the grid during the power grid failure, the grid-connected current will be increased, which will lead to the de-listing of the grid-connected photovoltaic system caused by overcurrent. In order to solve this problem, a new power control algorithm with current limitation based on positive and negative sequence control and a fixed power tracking control scheme for photovoltaic cells are proposed in this paper. Finally, a series of schemes to calculate the instantaneous active power and reactive power oscillation are derived. The most suitable scheme can be selected to eliminate the power oscillation according to the actual power network fault situation. Based on DSP and FPGA control system, this paper verifies some theoretical and experimental research on the three-level neutral-point clamped grid-connected inverter with LCL filter, and the experimental results verify the correctness of the theory.
【學位授予單位】：燕山大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TM464
本文編號：2261576
[Abstract]:Now with the development of new energy, a large number of photovoltaic power systems connected to the grid. Because of the voltage drop caused by circuit short circuit and other network faults, there are many problems to be solved urgently in the grid-connected control strategy. Therefore, grid-connected photovoltaic systems need to meet many grid-connected standards such as inverter fast and accurate synchronization technology, unbalanced current control, reactive power support, power factor correction and fault traversing. However, the common coupling point nonlinear load and the common two-phase and single-phase short-circuit in the power network will lead to the unbalanced and non-sinusoidal voltage of the power network, which makes the inverter synchronize the phase, instantaneous active power and reactive power. The positive and negative sequence components of DC side voltage, grid-connected current and voltage will produce double frequency oscillation which affects the performance of inverter. Based on the topology of three-level neutral-point clamped inverter, this paper provides many control schemes which can solve the problems of grid-connected variable oscillation and power network fault traversing ability. Firstly, in order to solve the problem that the three-level neutral-point clamping topology is prone to cause the neutral point potential imbalance in practical operation, the DC side neutral point potential control based on the principle of capacitance charge conservation is adopted to change the switching state of the inverter. Secondly, in order to solve the problem of power network synchronization in the event of asymmetric fault, this paper uses a novel decoupled double-synchronous reference coordinate system phase-locked loop to detect the positive sequence voltage and phase. This method can completely eliminate the phase detection error of the common synchronous reference coordinate PLL and can accurately separate the positive and negative sequence components of unbalanced grid voltage. In the design of current control strategy under asymmetrical fault condition, a new current control scheme based on PI control current loop in cross-decoupled double-synchronous reference coordinate system is proposed in this paper. This scheme can counteract the double frequency oscillation on the current component caused by the positive and negative sequence components of the current. However, in order to transmit all the power generated by photovoltaic cells to the grid during the power grid failure, the grid-connected current will be increased, which will lead to the de-listing of the grid-connected photovoltaic system caused by overcurrent. In order to solve this problem, a new power control algorithm with current limitation based on positive and negative sequence control and a fixed power tracking control scheme for photovoltaic cells are proposed in this paper. Finally, a series of schemes to calculate the instantaneous active power and reactive power oscillation are derived. The most suitable scheme can be selected to eliminate the power oscillation according to the actual power network fault situation. Based on DSP and FPGA control system, this paper verifies some theoretical and experimental research on the three-level neutral-point clamped grid-connected inverter with LCL filter, and the experimental results verify the correctness of the theory.
【學位授予單位】：燕山大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TM464
【參考文獻】
相關期刊論文 前7條
1 劉飛;查曉明;段善旭;;三相并網(wǎng)逆變器LCL濾波器的參數(shù)設計與研究[J];電工技術學報;2010年03期
2 張憲平;李亞西;潘磊;趙斌;許洪華;;三相電壓型整流器的LCL型濾波器分析與設計[J];電氣應用;2007年05期
3 唐麗娜;倪帥;戴鵬;徐立華;;NPC三電平整流器中點電位控制方法的研究[J];電氣傳動;2012年07期
4 原敬磊;張建成;;光伏發(fā)電系統(tǒng)定功率輸出模式研究[J];華東電力;2012年03期
5 王越;王念春;時斌;;太陽能光伏電池陣列仿真模型的研究[J];電工電氣;2009年10期
6 王飛;余世杰;蘇建徽;沈玉梁;汪海寧;;光伏并網(wǎng)發(fā)電系統(tǒng)的研究及實現(xiàn)[J];太陽能學報;2005年05期
7 郭小強;鄔偉揚;漆漢宏;;電網(wǎng)電壓畸變不平衡情況下三相光伏并網(wǎng)逆變器控制策略[J];中國電機工程學報;2013年03期
相關博士學位論文 前3條
1 龔宇雷;微電源并網(wǎng)同步檢測與定功率輸出控制技術研究[D];山東大學;2011年
2 劉飛;三相并網(wǎng)光伏發(fā)電系統(tǒng)的運行控制策略[D];華中科技大學;2008年
3 仇志凌;基于LCL濾波器的三相三線并網(wǎng)變流器若干關鍵技術研究[D];浙江大學;2009年
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