【作者】 何人望；

【导师】 尹项根；

【作者基本信息】 华中科技大学 ， 电力系统及其自动化， 2011， 博士

【摘要】 本文主要研究逆变技术在高压变频调速系统和光伏并网控制系统中应用的关键问题。能源危机日益严重。应付能源危机主要靠两方面：一是节约能源,一是开发利用新能源。节能的一项重要技术是基于逆变技术的变频调速。太阳能则是开发新能源方面的重点,而太阳能并网中的关键技术之一是逆变技术。而IGCT则是高压大功率逆变技术的主要器件。因此,迫切需要研究逆变技术在高压变频调速系统和光伏并网控制系统中的应用问题。在IGCT应用研究中,需要对其进行仿真。为了满足这一要求,本文提出了四模块封装的方法,将IGCT等效为稳态电路、开通暂态电路、关断暂态电路和开关信号延时电路四个电路,构建了IGCT的电路级模型,解决了IGCT性能仿真的难题。仿真波形与实验结果表明,该模型仿真精度高、速度快。研究成果可用于任何含有IGCT的电路中,包括逆变器。高压逆变器中,常使用IGCT双管串联来增大耐压。串联后,由于双管存在差异,必然会分压不均。因此必须设计动态均压电路来保护IGCT。本文设计了串联缓冲电路,并针对缓冲电路进行了PSIM仿真和试验,通过仿真波形和试验波形比较验证了缓冲电路对IGCT的保护效果。分析了常见的串联多重化结构、三电平结构以及多电平结构的主回路及其各自的优缺点。并通过分析比较,结合项目的实际情况和当前电力电子器件的发展水平,选定了中性点钳位(NPC)三电平结构作为变频器的拓扑结构。改善了高压变频器保护方案。方案对高压变频器的整流电路、逆变电路以及电动机负载等进行了全面有效保护。高压变频器的散热系统,直接关系到变频器能否安全稳定工作。针对主要热源功率二极管和IGCT,设计了高压变频器的散热系统。研究了IGCT在光伏并网控制中的应用问题。设计了光伏并网逆变电路。对光伏并网逆变器(含滤波器)进行了仿真研究。建立了电流滞环比较方式并网控制方式下的仿真模型,并利用仿真模型在不同滤波电路条件下对光伏并网逆变器进行仿真。仿真结果正确合理,仿真模型可用于光伏并网系统的进一步研究。总结了主要研究工作和重要结论,指出了未来研究工作的重点和方向。更多还原

【Abstract】 The dissertation studies some key problems about the inverter applications in high voltage variable-frequency drives and photovoltaic systems.Energy crisis is becoming more and more serious. There are two approaches to the crisis. One is energy saving. The other one is new energy exploiting. Variable-frequency drives are important technology of energy saving. New energy exploiting focused on solar energy. Yet the key technology in solar energy exploiting is the inverter technology. IGCT is the main device in an inverter. Therefore, it is imperative to study the key problems about the inverter applications in high voltage variable-frequency drives and photovoltaic systems. It is necessary to simulate IGCTs in their applications. To satisfy this necessity, the dissertation proposes a novel method based on four-module package. The IGCT is equivalently divided into four modules. These are:steady-state circuit, turn-on transient circuit, turn-off transient circuit and time-delay circuit. The IGCT model is constructed and the difficult problem of IGCT simulation is solved. The experimental results verify the correctness of the simulation study. The IGCT model can be used in any circuits with IGCTs, including inverters.Two IGCTs in series are often used in high voltage variable-frequency drives to increase total voltage. Yet the voltage will be unevenly divided because of the difference between these two IGCTs. Therefore, it is necessary to design a snubber circuit to protect the IGCTs. A series snubber circuit is designed and simulated with PSIM. The experimental results show that the IGCTs are well protected by the proposed snubber circuit.The dissertation analyzes the common multiple-cascade structure, the three-level NPC structure and multi-level voltage structure of the main circuits, points out their respective advantages and disadvantages. After thorough analysis and careful comparison, the three-level NPC (neutral point clamped) structure is chosen as the converter topology structure according to the actual situations of this project and the current development of power electronics. Much attention is paid to the analysis and design of the main circuit with the chosen three-level NPC structure. The dissertation also designs the control, protection and monitoring system of the inverter, studies the protection algorithms, completes hardware design and software development. It designs the hardware design and develops the software of the protection for the transformer, the rectifier-inverter circuits, and the motor.Heat sinking is critical to the safety and stability of the high voltage variable-frequency drives. A heat sinking system is designed considering the power diodes and the IGCTs as the main heat sources.The dissertation also studies problems in the inverter applications in photovoltaic systems. A grid-connected inverter is designed for the photovoltaic system. A model based on current hysteresis control is constructed and simulated with different filters. Simulation results are correct and rational. The model can be used in further researches on grid-connected photovoltaic systems.Finally, the dissertation summarizes the main research works and the obtained important conclusions, proposes the future research emphases and directions.更多还原