基于功率前饋的單級式三相光伏并網(wǎng)逆變器的研究
本文選題:單級式光伏逆變器 + 最大功率點跟蹤; 參考:《燕山大學》2014年碩士論文
【摘要】:單級式光伏并網(wǎng)系統(tǒng)僅需要一級能量變換就可以完成最大功率點跟蹤(MPPT)和并網(wǎng)兩個功能,因此在效率和成本上都有較大的優(yōu)勢,但是與此同時也會帶來一些缺點,如控制復雜,直流母線電壓過高等,所以深入研究單級式光伏并網(wǎng)逆變系統(tǒng),對于未來新能源問題的解決有重要的研究價值和研究意義。 本文以單級式三相光伏并網(wǎng)逆變器為研究對象。首先分析了光伏電池的原理與輸出特性并建立其數(shù)學模型,,根據(jù)光伏電池的輸出特性對比分析定電壓跟蹤法、擾動觀察法和電導增量法這三種常用MPPT算法的優(yōu)缺點。在此基礎上提出了一種“鐘擺式”MPPT算法,同時對該算法進行了理論分析,并將其與傳統(tǒng)擾動觀察法進行仿真對比,突出了“鐘擺式”MPPT算法的優(yōu)勢。 其次,對單級式三相光伏并網(wǎng)逆變器的數(shù)學模型與控制策略進行了詳細的研究與分析。針對傳統(tǒng)雙環(huán)控制中直流母線電壓響應慢,不利于MPPT的快速搜索,本文將功率前饋算法應用于本系統(tǒng)的的外環(huán)控制中,并將其與傳統(tǒng)的雙環(huán)PI控制進行仿真對比。此外,針對實際并網(wǎng)控制中調(diào)節(jié)器設計不合理,參數(shù)試湊等問題,對PI調(diào)節(jié)器參數(shù)設計進行了深入研究,通過詳細的理論推導得出一種新型設計PI調(diào)節(jié)器的方法。在完成MPPT算法與逆變器控制策略的分析后,將“鐘擺式”MPPT算法與基于功率前饋的雙環(huán)控制相結合,對單級式三相光伏并網(wǎng)逆變系統(tǒng)進行了整體的仿真研究。 最后,本文對整個系統(tǒng)的硬件和軟件進行了詳細的設計。在設計的基礎上搭建了一套3kVA的單級式三相光伏并網(wǎng)逆變器樣機,通過數(shù)字控制,完成了整個系統(tǒng)的實驗驗證。實驗結果驗證了“鐘擺式”MPPT算法以及基于功率前饋控制方案的可行性和有效性。
[Abstract]:The single-stage photovoltaic grid-connected system needs only one stage energy conversion to complete the two functions of maximum power point tracking (MPPT) and grid-connected, so it has great advantages in efficiency and cost, but at the same time, it will bring some disadvantages, such as complex control. The DC bus voltage is too high, so the research of single-stage photovoltaic grid-connected inverter system has important research value and significance for solving the problem of new energy in the future. In this paper, the single-stage three-phase photovoltaic grid-connected inverter is taken as the research object. Firstly, the principle and output characteristics of photovoltaic cells are analyzed and their mathematical models are established. According to the output characteristics of photovoltaic cells, the advantages and disadvantages of three common MPPT algorithms, namely, constant voltage tracking method, disturbance observation method and conductance increment method, are compared and analyzed. On this basis, a kind of "pendulum" MPPT algorithm is proposed, and the theoretical analysis of the algorithm is made, and compared with the traditional perturbation observation method, the advantages of the "pendulum" MPPT algorithm are highlighted. Secondly, the mathematical model and control strategy of single-stage three-phase photovoltaic grid-connected inverter are studied and analyzed in detail. In view of the slow voltage response of DC bus in the traditional double loop control, which is not conducive to the fast search of MPPT, this paper applies the power feedforward algorithm to the outer loop control of the system, and compares it with the traditional double loop Pi control. In addition, the parameter design of Pi regulator is studied deeply, and a new design method of Pi regulator is derived through the detailed theoretical derivation, aiming at the unreasonable design of regulator and parameter trial and error in practical grid-connected control. After the analysis of MPPT algorithm and inverter control strategy, the "pendulum" MPPT algorithm is combined with the dual-loop control based on power feedforward to simulate the single-stage three-phase photovoltaic grid-connected inverter system. Finally, the hardware and software of the whole system are designed in detail. On the basis of the design, a 3kVA single-stage three-phase photovoltaic grid-connected inverter prototype is built, and the whole system is verified by digital control. The experimental results demonstrate the feasibility and effectiveness of the "pendulum" MPPT algorithm and the power feedforward control scheme.
【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;TM615
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