發(fā)布時間：2018-04-09 11:57

  本文選題：并網(wǎng)逆變器　切入點：三電平　出處：《華南理工大學》2014年碩士論文

【摘要】：與傳統(tǒng)的兩電平并網(wǎng)逆變器相比，三電平并網(wǎng)逆變器的開關(guān)器件承受電壓低、輸出電流諧波含量少、開關(guān)頻率低和電磁干擾小，在高壓、大功率場合得到了廣泛應(yīng)用。然而，三電平并網(wǎng)逆變器開關(guān)器件和控制目標較多，控制較復(fù)雜，為了提高光伏并網(wǎng)逆變器性能和效率，需要對三電平并網(wǎng)逆變器的控制系統(tǒng)進行合理設(shè)計。為此本文對三電平光伏并網(wǎng)逆變器的控制技術(shù)進行研究，本文的主要研究內(nèi)容如下： 1、對比分析了傳統(tǒng)三電平逆變器拓撲的優(yōu)缺點，給出了一種T型三電平逆變器拓撲，與二極管鉗位型相比，該拓撲具有成本低、功耗小且能平衡所有開關(guān)損耗的優(yōu)點，基于此拓撲建立了三電平光伏并網(wǎng)逆變器的數(shù)學模型，為系統(tǒng)的控制設(shè)計打下基礎(chǔ)。 2、對三電平光伏并網(wǎng)逆變器的控制技術(shù)進行了分析，選擇對模型預(yù)測控制技術(shù)進行深入研究，該控制技術(shù)相比于傳統(tǒng)的控制技術(shù)控制靈活，通過調(diào)整目標函數(shù)的權(quán)重因子即可實現(xiàn)對三電平光伏并網(wǎng)逆變器綜合性能的優(yōu)化，且無需調(diào)制器，直接根據(jù)目標函數(shù)選擇最優(yōu)的開關(guān)狀態(tài)，在電流跟蹤性能和中點電位平衡控制方面具有較快的響應(yīng)速度。在分析模型預(yù)測控制基本原理的基礎(chǔ)上，建立了三電平光伏并網(wǎng)逆變器的離散預(yù)測模型和目標函數(shù)，并對傳統(tǒng)模型預(yù)測控制技術(shù)存在的延時、計算量大的問題，，給出解決方案。 3、分析了電網(wǎng)不平衡時三電平并網(wǎng)逆變器的基本問題，給出了基于模型預(yù)測控制的抑制并網(wǎng)電流負序分量的不平衡控制技術(shù)，針對不平衡電網(wǎng)下需要檢測電網(wǎng)電壓正負序分量和傳統(tǒng)鎖相環(huán)無法快速準確地鎖定電網(wǎng)電壓相位的問題，給出了基于解耦的雙同步坐標系的正負序分離方法和鎖相方法，該方法可以在不平衡電網(wǎng)下快速準確地檢測電網(wǎng)電壓正負序分量并鎖定電網(wǎng)電壓相位。 4、基于Matlab/Simulink搭建了系統(tǒng)仿真模型，對三電平光伏并網(wǎng)逆變器的模型預(yù)測控制效果進行了仿真分析，仿真結(jié)果表明本文設(shè)計的模型預(yù)測控制器能夠很好地跟蹤參考電流，控制中點電位平衡，且在不平衡電網(wǎng)下控制輸出電流平衡，動態(tài)和穩(wěn)態(tài)性能較好。 5、在仿真分析的基礎(chǔ)上，設(shè)計了三電平光伏并網(wǎng)逆變器的硬件和軟件系統(tǒng)，搭建了30kW三電平光伏并網(wǎng)逆變器實驗電路，通過實驗驗證了模型預(yù)測控制技術(shù)的有效性。實驗結(jié)果表明本文設(shè)計的模型預(yù)測控制器能夠很好地控制并網(wǎng)電流和中點電位平衡，且并網(wǎng)電流THD較小，系統(tǒng)功率因數(shù)較高，符合系統(tǒng)設(shè)計要求。
[Abstract]:Compared with the traditional two-level grid-connected inverter, the three-level grid-connected inverter is widely used in high-voltage and high-power applications because of its lower voltage, less harmonic output current, lower switching frequency and less electromagnetic interference.However, there are many switching devices and control targets for the three-level grid-connected inverter and the control is more complex. In order to improve the performance and efficiency of the photovoltaic grid-connected inverter, it is necessary to design the control system of the three-level grid-connected inverter reasonably.Therefore, the control technology of three-level photovoltaic grid-connected inverter is studied in this paper. The main contents of this paper are as follows:1. The advantages and disadvantages of the traditional three-level inverter topology are analyzed, and a T type three-level inverter topology is presented. Compared with the diode clamping type, the topology has the advantages of low cost, low power consumption and balance of all switching losses.Based on this topology, the mathematical model of the three-level photovoltaic grid-connected inverter is established, which lays a foundation for the control design of the system.2. The control technology of three-level photovoltaic grid-connected inverter is analyzed, and the model predictive control technology is deeply studied. The control technology is more flexible than the traditional control technology.By adjusting the weight factor of the objective function, the comprehensive performance of the three-level photovoltaic grid-connected inverter can be optimized, and the optimal switching state can be selected directly according to the objective function without modulator.It has fast response speed in current tracking performance and midpoint potential balance control.On the basis of analyzing the basic principle of model predictive control, the discrete prediction model and objective function of three-level photovoltaic grid-connected inverter are established.3. The basic problems of three-level grid-connected inverter in unbalanced power network are analyzed, and the unbalanced control technology based on model predictive control is presented to suppress the negative sequence component of grid-connected current.In order to solve the problem that it is necessary to detect the positive and negative sequence components of power network voltage and the traditional phase-locked loop can not lock the voltage phase quickly and accurately under unbalanced power grid, a method of separating positive and negative sequence and phase lock based on decoupled double synchronous coordinate system is presented.This method can quickly and accurately detect the positive and negative sequence components and lock the voltage phase in unbalanced power systems.4. The system simulation model based on Matlab/Simulink is built, and the model predictive control effect of three-level photovoltaic grid-connected inverter is simulated and analyzed. The simulation results show that the model predictive controller designed in this paper can track the reference current well.The dynamic and steady performance of the output current balance is better than that of the control of the neutral point potential balance and the output current balance under the unbalanced power network.
【學位授予單位】：華南理工大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TM464;TM615

【參考文獻】

相關(guān)期刊論文 前2條

1 蔣衛(wèi)宏;;不對稱電網(wǎng)故障下PWM整流器的控制策略研究[J];系統(tǒng)仿真學報;2007年15期

2 孔雪娟,王荊江,彭力,康勇,陳堅;基于內(nèi)模原理的三相電壓源型逆變電源的波形控制技術(shù)[J];中國電機工程學報;2003年07期

本文編號：1726322