LCT谐振式高频隔离型光伏并网逆变器的研究

发布时间：2018-07-23 20:36

【摘要】：从能源的长远发展来看,新能源终将取代常规能源。而从近期发展来看,新能源势必将成为电力市场的重要组成部分。出于政策的扶持,光伏发电产业作为新能源领域的重要组成部分在近十年来快速的发展。光伏并网逆变器也作为能量转换与控制的核心部件,成为国内外学者研究的重点。根据电力装置小型化、高功率密度的发展趋势,本文研究了一种LCT谐振式高频隔离型光伏并网逆变器,其具有质量轻、功率密度高、电气隔离等优点,适用于单相中小功率分布式光伏并网发电系统。首先,介绍了课题提出的逆变器电路拓扑,简述了电路的工作模式,说明了电路各个模块的作用。详细的数学推导了正弦脉宽脉位调制方式,分析了电路工作在谐振状态时,移相角小于临界移相角时的各个工作模态,证明了该方案的可行性。接着对电路模型进行了稳态分析,建立谐振等效模型,得到了谐振单元的参数对逆变器的增益、软开关及效率的影响关系,给出了设计谐振参数的原则。其次,根据电路拓扑的工作特点,设计了包含电压前馈和死区补偿等环节的闭环控制策略,从而实现逆变器单位功率因数高效稳定的并网运行。对最大功率点跟踪、死区补偿、锁相环技术和孤岛检测等环节从原理到仿真进行了系统的说明。随后从理论上对控制系统进行了稳定性分析,验证了闭环系统的可行性,建立了整个逆变系统模型进行了验证。最后,根据提出的电路拓扑和控制策略,设计了样机的硬件系统和软件系统,实现了逆变器在闭环控制系统下稳定高效的运行。通过对样机各个环节波形的分析,证明了软硬件系统的可行性和理论的正确性,为后续研究该类逆变器提供参考。
[Abstract]:From the long-term development of energy, new energy will replace conventional energy. From the recent development, new energy is bound to become an important part of the electricity market. As an important part of the new energy field, photovoltaic power generation industry has developed rapidly in the past decade. Photovoltaic grid-connected inverter, as the core component of energy conversion and control, has become the focus of scholars at home and abroad. According to the development trend of miniaturization and high power density of power equipment, this paper studies a LCT resonant high-frequency isolated photovoltaic grid-connected inverter, which has the advantages of light weight, high power density and electrical isolation. It is suitable for single phase, medium and small power distributed photovoltaic grid-connected generation system. Firstly, the topology of inverter is introduced, the working mode of the circuit is briefly described, and the function of each module of the circuit is explained. The sinusoidal pulse width modulation mode is deduced in detail, and the working modes when the phase shift angle is less than the critical phase shift angle when the circuit works in the resonant state are analyzed, and the feasibility of the scheme is proved. Then the steady state of the circuit model is analyzed and the resonant equivalent model is established. The influence of the resonant cell parameters on the gain, soft switching and efficiency of the inverter is obtained, and the principle of designing the resonant parameters is given. Secondly, according to the working characteristics of the circuit topology, a closed-loop control strategy including voltage feedforward and dead-time compensation is designed to realize efficient and stable grid-connected operation of inverter unit power factor. The maximum power point tracking, dead-zone compensation, phase-locked loop technology and islanding detection are systematically explained from principle to simulation. Then the stability of the control system is analyzed theoretically, the feasibility of the closed-loop system is verified, and the whole inverter system model is established. Finally, according to the proposed circuit topology and control strategy, the hardware and software systems of the prototype are designed, and the inverter runs stably and efficiently under the closed-loop control system. By analyzing the waveforms of each link of the prototype, the feasibility of the hardware and software system and the correctness of the theory are proved, which provides a reference for the further study of this kind of inverter.
【学位授予单位】：北方工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM464;TM615

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