一種基于H6橋的單相光伏并網(wǎng)逆變器的研究
發(fā)布時(shí)間:2018-05-16 21:49
本文選題:并網(wǎng)逆變器 + 共模電流。 參考:《陜西科技大學(xué)》2017年碩士論文
【摘要】:在傳統(tǒng)能源短缺和環(huán)境日益惡化的大背景下,尋求環(huán)保的可再生能源迫在眉睫。太陽(yáng)能作為一種綠色、儲(chǔ)存量足的可再生能源越來(lái)越受到關(guān)注,其中,光伏并網(wǎng)發(fā)電技術(shù)是利用太陽(yáng)能的有效途徑之一,而并網(wǎng)逆變器作為光伏并網(wǎng)發(fā)電系統(tǒng)的核心部件,其拓?fù)浣Y(jié)構(gòu)和并網(wǎng)控制技術(shù)決定了光伏并網(wǎng)發(fā)電系統(tǒng)的發(fā)電效率和電能質(zhì)量。本文采用了一種高效的H6拓?fù)?解決了傳統(tǒng)橋式拓?fù)溆糜诜歉綦x系統(tǒng)存在的逆變效率低、共模電流大等問題。本文所做的主要工作包括以下幾個(gè)方面:(1)非隔離型傳統(tǒng)橋式逆變器拓?fù)浼癏6拓?fù)涞墓材k娏鞣治觥7治隽朔歉綦x型單相光伏并網(wǎng)逆變器拓?fù)淦毡榇嬖诘募纳娙莺椭绷鞣至繂栴}。在非隔離型傳統(tǒng)橋式拓?fù)淠P偷幕A(chǔ)之上,詳細(xì)分析了此類拓?fù)涔材k娏鳟a(chǎn)生的機(jī)理,得到了抑制共模電流的條件,給出了一種能夠有效抑制共模電流的H6逆變拓?fù)洹?2)基于H6橋兩級(jí)式光伏并網(wǎng)系統(tǒng)總體控制方案的設(shè)計(jì)。前級(jí)DC-DC電路實(shí)現(xiàn)最大功率點(diǎn)跟蹤和母線電壓穩(wěn)定,后級(jí)H6逆變器實(shí)現(xiàn)并網(wǎng)控制功能。結(jié)合本系統(tǒng)實(shí)際情況,選擇L型濾波器,并對(duì)L型濾波器參數(shù)進(jìn)行了設(shè)計(jì)。在電感電流連續(xù)模式下,分析了Boost電路的升壓原理,為后面的Matlab仿真提供理論基礎(chǔ)。(3)研究了并網(wǎng)逆變器的控制策略。對(duì)前級(jí)部分和后級(jí)部分的控制策略進(jìn)行了獨(dú)立的設(shè)計(jì)。針對(duì)傳統(tǒng)電導(dǎo)增量法存在的“誤判”問題,采用了一種基于恒定電壓法結(jié)合變步長(zhǎng)電導(dǎo)增量法的MPPT控制策略;重點(diǎn)分析了并網(wǎng)電流逆變控制技術(shù),分別探究了PI控制和PR控制的原理及優(yōu)缺點(diǎn),針對(duì)兩種控制方法的局限性,提出了基于PI+QPR復(fù)合并網(wǎng)控制策略,并對(duì)控制器進(jìn)行理論分析,對(duì)改善并網(wǎng)電流質(zhì)量有一定的意義。(4)基于H6橋單相光伏并網(wǎng)逆變系統(tǒng)的仿真分析。在Matlab R2016b/Simulink平臺(tái)上搭建基于H6橋單相光伏并網(wǎng)逆變系統(tǒng)仿真模型,根據(jù)控制器所設(shè)計(jì)的參數(shù),分別對(duì)PR控制、PI控制和PI+QPR控制仿真實(shí)驗(yàn),從無(wú)靜差跟蹤能力、抗干擾性和抑制直流分量能力等三個(gè)方面性能進(jìn)行對(duì)比,來(lái)體現(xiàn)PI+QPR復(fù)合控制的優(yōu)越性,另外,復(fù)合控制還具備對(duì)電網(wǎng)低次諧波的補(bǔ)償能力;同時(shí),通過(guò)仿真驗(yàn)證了恒定電壓法結(jié)合變步長(zhǎng)電導(dǎo)增量法良好的動(dòng)態(tài)特性。(5)基于H6橋光伏并網(wǎng)逆變器的軟硬件設(shè)計(jì)。研制一臺(tái)1.5kW的H6橋單相光伏并網(wǎng)逆變器實(shí)驗(yàn)樣機(jī),設(shè)計(jì)了H6逆變器的硬件部分和軟件部分,并對(duì)H6橋樣機(jī)進(jìn)行性能測(cè)試,得到了部分實(shí)驗(yàn)波形和數(shù)據(jù),并對(duì)樣機(jī)性能進(jìn)行分析。仿真和實(shí)驗(yàn)結(jié)果表明:基于H6拓?fù)涮岢龅腜I+QPR控制策略不僅可以實(shí)現(xiàn)無(wú)靜差跟蹤,而且還可以抑制低頻直流分量,有效地減小了并網(wǎng)電流THD,實(shí)現(xiàn)了單位功率因數(shù)并網(wǎng)。
[Abstract]:Under the background of the shortage of traditional energy and the worsening of environment, it is urgent to seek renewable energy for environmental protection. Solar energy, as a kind of green and abundant renewable energy, has been paid more and more attention. Among them, grid-connected photovoltaic (PV) grid-connected power generation technology is one of the effective ways to utilize solar energy, and grid-connected inverter is the core component of grid-connected photovoltaic power generation system. Its topology and grid-connected control technology determine the generation efficiency and power quality of grid-connected photovoltaic system. In this paper, an efficient H6 topology is used to solve the problems of low inverter efficiency and large common-mode current in traditional bridge topology for non-isolated systems. The main work of this paper includes the following aspects: 1) Common-mode current analysis of traditional bridge inverter topology and H6 topology. The parasitic capacitance and DC component problems of non-isolated single-phase photovoltaic grid-connected inverter topology are analyzed. Based on the traditional bridge topology model, the mechanism of the common mode current is analyzed in detail, and the condition of restraining the common mode current is obtained. A H6 inverter topology, which can effectively suppress the common-mode current, is presented. The overall control scheme of the two-stage photovoltaic grid-connected system based on H6 bridge is designed. The front-stage DC-DC circuit achieves maximum power point tracking and bus voltage stability, while the hind H6 inverter realizes grid-connected control function. According to the actual situation of the system, the L type filter is selected and the parameters of L type filter are designed. In the continuous mode of inductance current, the boost principle of Boost circuit is analyzed, and the control strategy of grid-connected inverter is studied. The control strategy of the former part and the later part is designed independently. Aiming at the problem of "misjudgment" in traditional conductance increment method, a MPPT control strategy based on constant voltage method and variable step length increment method is adopted, and the grid-connected current inverter control technique is analyzed emphatically. The principle, advantages and disadvantages of Pi control and PR control are discussed respectively. Aiming at the limitation of the two control methods, a hybrid grid-connected control strategy based on Pi QPR is proposed, and the controller is analyzed theoretically. It is significant to improve the quality of grid-connected current. 4) Simulation analysis of single-phase photovoltaic grid-connected inverter system based on H6 bridge. The simulation model of single-phase photovoltaic grid-connected inverter system based on H6 bridge is built on Matlab R2016b/Simulink platform. According to the parameters designed by the controller, the simulation experiments of PR control Pi control and Pi QPR control are carried out, respectively. In order to reflect the superiority of Pi QPR compound control, the performance of anti-interference and DC component suppression is compared. In addition, the compound control also has the ability to compensate the low order harmonics of the power network, at the same time, The software and hardware design of H6 bridge photovoltaic grid-connected inverter based on constant voltage method combined with variable step length conductance increment method is verified by simulation. An experimental prototype of H6 bridge single-phase photovoltaic grid-connected inverter of 1.5kW is developed. The hardware and software parts of H6 inverter are designed. The performance of H6 bridge prototype is tested, and some experimental waveforms and data are obtained, and the performance of the prototype is analyzed. The simulation and experimental results show that the Pi QPR control strategy based on H6 topology can not only realize static error tracking, but also suppress low-frequency DC component, reduce grid-connected current effectively, and realize grid-connected unit power factor.
【學(xué)位授予單位】:陜西科技大學(xué)
【學(xué)位級(jí)別】:碩士
【學(xué)位授予年份】:2017
【分類號(hào)】:TM464;TM615
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