【摘要】：隨著人類面臨的能源危機和環(huán)境問題越來越嚴峻，作為一種清潔的可再生能源，太陽能光伏發(fā)電近年來得到了迅猛的發(fā)展。光伏發(fā)電系統(tǒng)常用于解決偏遠地區(qū)的供電需求，而偏遠地區(qū)、海島等末端電網(wǎng)通常為相對較小的負載設(shè)計，其電力供應(yīng)多為中低壓等級，，電網(wǎng)阻抗較高、短路容量較低，呈現(xiàn)弱電網(wǎng)特性。弱電網(wǎng)低短路容量、高電網(wǎng)阻抗的電氣特性對光伏并網(wǎng)發(fā)電系統(tǒng)的穩(wěn)定運行提出了新的挑戰(zhàn)。為此，本文針對弱電網(wǎng)條件下的光伏并網(wǎng)逆變器，從電網(wǎng)同步技術(shù)、穩(wěn)定性控制方法等角度提出改善逆變器并網(wǎng)性能的具體措施和控制策略，保障其在弱電網(wǎng)條件下能夠可靠穩(wěn)定運行。 本文首先建立兩級式單相光伏并網(wǎng)逆變器拓撲結(jié)構(gòu)系統(tǒng)模型，推導出電流源型逆變器輸出阻抗一般表達式，并分析系統(tǒng)各參數(shù)變化對輸出阻抗的影響及變化規(guī)律；其次建立電流源型光伏并網(wǎng)發(fā)電系統(tǒng)的阻抗穩(wěn)定性判斷標準，在此基礎(chǔ)上研究不同電網(wǎng)條件對逆變器穩(wěn)定性的影響，通過分析發(fā)現(xiàn)電網(wǎng)阻抗的增大會使系統(tǒng)穩(wěn)定性降低，結(jié)合濾波參數(shù)對輸出阻抗的影響提出虛擬電抗控制方法來提高系統(tǒng)穩(wěn)定性；與此同時，針對弱電網(wǎng)下傳統(tǒng)過零檢測同步方法存在的弊端，提出采用基于二階廣義積分器鎖頻環(huán)技術(shù)來解決電網(wǎng)同步問題，以實現(xiàn)弱電網(wǎng)下逆變器可靠、穩(wěn)定地并網(wǎng)。 最后，搭建了弱電網(wǎng)下以TMS320F2812為控制芯片的單相光伏并網(wǎng)逆變器實驗平臺，設(shè)計硬件電路及軟件控制算法，在此平臺上進行實驗驗證。實驗結(jié)果驗證了本文提出的虛擬電抗控制方法以及電網(wǎng)同步方法在弱電網(wǎng)下應(yīng)用的正確性和有效性，與理論分析相符。
[Abstract]:As a kind of clean renewable energy, solar photovoltaic power has been developing rapidly in recent years with the increasingly severe energy crisis and environmental problems faced by human beings. Photovoltaic power generation systems are often used to solve the power demand in remote areas. In remote areas, islands and other terminal networks are usually designed for relatively small loads. The power supply is mostly of medium and low voltage grade, with high impedance and low short-circuit capacity. Presents the characteristic of weak current network. The low short-circuit capacity of weak grid and the electrical characteristics of high impedance put forward a new challenge to the stable operation of grid-connected photovoltaic system. Therefore, aiming at the grid-connected photovoltaic inverter under the condition of weak grid, this paper puts forward the concrete measures and control strategies to improve the grid-connected performance of the inverter from the point of view of grid synchronization technology and stability control method. It can operate reliably and stably under the condition of weak electric network. In this paper, the topology structure model of two-stage single-phase photovoltaic grid-connected inverter is established, and the general expression of output impedance of current-source inverter is deduced, and the influence of system parameters on output impedance is analyzed. Secondly, the impedance stability criterion of current source photovoltaic grid-connected generation system is established. On this basis, the influence of different grid conditions on inverter stability is studied. It is found that the increase of grid impedance will reduce the stability of the system. Combined with the influence of filter parameters on the output impedance, a virtual reactance control method is proposed to improve the stability of the system. At the same time, aiming at the disadvantages of the traditional zero crossing detection and synchronization method under weak electric network, a frequency locking loop technique based on the second order generalized integrator is proposed to solve the problem of power network synchronization, so as to realize the reliable and stable grid connection of the inverter under the weak electric network. Finally, the experiment platform of single-phase photovoltaic grid-connected inverter with TMS320F2812 as control chip is built, and the hardware circuit and software control algorithm are designed and verified on this platform. The experimental results verify the correctness and effectiveness of the proposed virtual reactance control method and the power grid synchronization method under the weak current network, which is consistent with the theoretical analysis.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TM464

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