MW级光伏并网逆变器的研究

发布时间：2018-01-05 19:11

本文关键词：MW级光伏并网逆变器的研究　出处：《北京交通大学》2014年硕士论文　论文类型：学位论文

【摘要】：大规模光伏电站是当前国内最主要的新能源发电形式。MW级光伏并网逆变器因其在高效率、高功率等级、高可靠性等方面的优势,也将成为业界发展的重要方向。因此,本文围绕MW级光伏并网逆变器展开研究,主要完成了MW级光伏并网逆变器设计与光伏并网逆变器低电压穿越技术的研究,并通过搭建系统仿真模型与实验平台对样机整体设计与性能进行了验证。首先,功率组件设计是MW级光伏并网逆变器设计的重点和难点。其设计应综合考虑系统分布电感影响。为了便于组装与维护,本文功率组件采用模块化设计,主要完成了直流支撑电容选择、吸收电路设计、组件并联均流电路设计和水冷散热设计等。并结合仿真、组件测试与整机实验验证了组件设计的合理性与可靠性。其次,分析研究了MW级光伏并网逆变器的控制策略并完成LCL滤波电路的设计。建立了系统的数学模型,确立了基于网压定向的双闭环控制策略。在此基础上,完成了LCL滤波电路的参数计算。并通过仿真和实验验证了系统控制策略的稳定性和LCL滤波电路设计的正确性。第三,针对光伏系统共模漏电流问题,设计了共模抑制滤波电路。分析和研究了系统共模漏电流的产生机理和影响因素。在此基础上,研究了改进SVPWM调制策略与共模抑制滤波电路对共模漏电流抑制原理。从系统角度出发,确定了外加共模滤波电路抑制du/dt和漏电流的方法,并通过实验进行了验证。第四,对电网电压对称跌落与不对称跌落情况下光伏发电系统的低电压穿越控制策略进行了分析和研究。根据国网对光伏低电压穿越的最新规定,分析了网压对称跌落时的无功补偿策略；讨论研究了网压不对称跌落时电压和电流的正负序分离方法以及控制目标。并对光伏并网逆变器在对称与不对称电网电压跌落情况下的控制策略进行仿真分析和实验验证。最后在样机的基础上,通过实验完成并网电流总谐波THD、功率因数、系统效率、器件温升、低电压穿越能力等的测试,综合实验结果分析表明MW级光伏并网逆变器满足设计要求。
[Abstract]:Large-scale photovoltaic power station is the most important new energy generation form in China at present. MW class photovoltaic grid-connected inverter has the advantages of high efficiency, high power level, high reliability and so on. It will also become an important direction of development in the industry. Therefore, this paper focuses on the research of MW photovoltaic grid-connected inverter. The design of MW class photovoltaic grid-connected inverter and the low-voltage traversing technology of photovoltaic grid-connected inverter are studied, and the overall design and performance of the prototype are verified by building the system simulation model and experimental platform. First of all, the power module design is the key and difficult point in the design of MW class photovoltaic grid-connected inverter. Its design should take into account the influence of distributed inductance of the system, in order to facilitate the assembly and maintenance. In this paper, the modular design of the power module, mainly completed the selection of DC support capacitance, absorption circuit design, components parallel current sharing circuit design and water cooling heat dissipation design, and combined with simulation. The rationality and reliability of the component design are verified by the component test and the whole machine experiment. Secondly, the control strategy of MW class photovoltaic grid-connected inverter is analyzed and the design of LCL filter circuit is completed. The mathematical model of the system is established. A double closed loop control strategy based on network voltage orientation is established. The parameter calculation of the LCL filter circuit is completed, and the stability of the control strategy and the correctness of the design of the LCL filter circuit are verified by simulation and experiment. Thirdly, aiming at the common mode leakage current of photovoltaic system, the common mode suppression filter circuit is designed, and the mechanism and influencing factors of the common mode leakage current are analyzed and studied. The improved SVPWM modulation strategy and the common mode suppression filter circuit for the common mode leakage current suppression principle are studied. From the system point of view, the method of external common mode filter circuit to suppress du/dt and leakage current is determined. It is verified by experiments. In 4th, the low voltage traversing control strategy of photovoltaic power system under the condition of symmetrical drop and asymmetric drop is analyzed and studied. According to the latest regulation of photovoltaic low voltage traversing in national network. The reactive power compensation strategy for symmetrical drop of network pressure is analyzed. In this paper, the positive and negative sequence separation method of voltage and current during asymmetric drop of grid voltage and its control target are discussed, and the control strategy of photovoltaic grid-connected inverter under the condition of symmetrical and asymmetric voltage drop of power network is simulated and analyzed. Experimental verification. Finally, on the basis of the prototype, the total harmonic THD, power factor, system efficiency, device temperature rise and low voltage traversing ability of grid-connected current are tested through experiments. Comprehensive experimental results show that MW class photovoltaic grid-connected inverter meets the design requirements.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM464

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