具有共模漏电流抑制能力的单相无变压器型光伏逆变技术研究
发布时间：2018-12-18 06:16
【摘要】：近年来,全球环境污染与能源短缺等问题不断加剧,世界各国纷纷从战略的角度加强扶持清洁可再生能源的发展。太阳能光伏发电因其资源丰富、清洁高效的特点而受到了广泛的关注。随着光伏发电行业相关技术的深入发展,光伏发电系统的成本不断降低,全球的光伏装机总量持续攀升。光伏发电技术的应用也已经进入了由政策驱动逐渐向市场驱动的过渡阶段。但是,光伏发电系统前期投入高,成本回收周期长,因此如何进一步地降低系统成本,提高系统的发电效率及其可靠性,进而缩短投资回收周期成为了光伏发电行业最为关注的问题。在户用型分布式光伏并网发电系统中,无变压器型逆变器因成本低、电能转换效率高的优点而倍受用户以及光伏系统集成商的青睐。但是,在无变压器型系统中,并网逆变器与光伏电池板的寄生电容以及电网会构成共模回路,若并网系统的共模电压存在高频脉动,则会在回路中产生不可忽视的共模漏电流,导致并网逆变系统无法满足并网标准中关于共模漏电流限值的规定。 本文围绕无变压器型光伏并网系统中的共模漏电流问题展开研究。文章分析了无变压器型电路的共模漏电流抑制条件,得到了两类具有共模漏电流抑制能力的单相拓扑结构：基于对称电感配置的电路结构和基于非对称电感配置的电路结构。继而从这两种电路结构分别出发,探索具有共模漏电流抑制能力的单相逆变电路的形成方法以及共模漏电流的优化方案。 首先,论文从高性能的HERIC电路推导得到了基于对称电感配置结构的混合全桥电路。通过对混合全桥电路的基本工作模态的分析,证明了该电路具有共模漏电流抑制能力的结论。在此基础上,文中给出了混合全桥电路的PWM控制方法,并且分析了该PWM控制策略下的混合全桥电路的工作特性。讨论了滤波电感不对称、开关动作不同步等电路非理想因素对电路的共模特性造成的影响,并给出了工程化时的共模特性优化方法。对比了混合全桥电路结构与其他对称电感配置电路的电路特性,强调了混合全桥电路的工业应用价值。并搭建了3kW的实验测试平台,验证了混合全桥结构的正确性。 其次,论文分析了电路中的寄生参数以及参数差异性对基于对称电感结构的无变压器型逆变电路中的共模漏电流的影响,并且以highly efficient and reliable inverter concept (HERIC)电路为例,给出了系统寄生参数相关的共模谐振电路模型,得到高频共模电压扰动与电路寄生参数之间的关系。基于上述分析,提出了进一步消除系统高频共模漏电流的共模电压箝位结构,并且将该结构运用于已有的全桥型对称电感配置电路进行优化,有效降低了已有拓扑方案中的共模电压的高频扰动,减小了电路寄生参数对系统共模漏电流的影响。并以基于有源电压箝位的HERIC电路为例,验证了共模电压箝位结构的有效性。 再次,提出了一种基于非对称电感配置结构的带有飞跨电容结构的多电平电路。该电路由飞跨电容三电平Buck结构与工频换相结构组合而成,不仅继承了多电平电路转换效率高、滤波电感小的优点,而且保留了工频换相结构对电路中的高频共模漏电流的抑制能力,降低了电路直流输入电压。通过对该电路的工作模态的分析,提出了相对应的PWM控制方法。然后从优化电路转换效率和功率密度的角度出发,给出了电路中参数的设计方法,并通过实验测试平台,验证了该电路的工作特性。 最后,运用上述理论,结合并网标准以及安全规范,设计完成了具有高可靠性、高转换效率的3kW的单相非隔离光伏并网逆变器产品,该产品经过实践论证与第三方机构的评测,已基本达到了工业界主流产品的水平。
[Abstract]:In recent years, the problems of global environmental pollution and energy shortage have been increasing, and the countries of the world have stepped up the development of supporting clean renewable energy from a strategic point of view. The solar photovoltaic power generation has received extensive attention due to its rich resources and high efficiency. With the deep development of the related technologies of the photovoltaic power generation industry, the cost of the photovoltaic power generation system is continuously reduced, and the total amount of the photovoltaic installation in the world continues to climb. The application of PV power generation technology has also entered a transition period driven by policy to market. However, the initial investment of the photovoltaic power generation system is high and the cost recovery period is long, so the system cost can be further reduced, the power generation efficiency and the reliability of the system can be improved, and the investment recovery period is shortened to become the most important problem in the photovoltaic power generation industry. In the household-type distributed photovoltaic grid-connected power generation system, the non-transformer type inverter is highly favored by the users and the integrator of the photovoltaic system because of the advantages of low cost and high conversion efficiency of the electric energy. in the transformer-free system, however, the parasitic capacitance of the grid-connected inverter and the photovoltaic cell panel and the power grid form a common-mode loop, The grid inverter system can not meet the requirements of the common mode leakage current limit in the network standard. In this paper, a research on the leakage current of the co-mode in a non-transformer type photovoltaic grid-connected system In this paper, the common mode leakage current suppression condition of the non-transformer type circuit is analyzed, and two types of single-phase topological structure with common mode leakage current suppression capability are obtained: the circuit structure based on the symmetric inductance configuration and the circuit junction based on the asymmetric inductance configuration The method of forming a single-phase inverter circuit with a common-mode leakage current suppression capability and an optimization method of the total-mode leakage current are explored from the two circuit structures, respectively. First, the thesis derives the hybrid system based on the symmetric inductance configuration structure from the high-performance HERIC circuit. Based on the analysis of the basic working mode of the hybrid full bridge circuit, it is proved that the circuit has a common mode leakage current suppression capability In this paper, the PWM control method of the hybrid full bridge circuit is given, and the work of the hybrid full bridge circuit under the PWM control strategy is analyzed. The influence of non-ideal factors such as the asymmetry of the filter inductance and the non-synchronization of the switch action on the model property of the circuit is discussed, and the model of the model is also given. The circuit characteristics of the hybrid full bridge circuit structure and other symmetrical inductance configuration circuits are compared, and the industry of the hybrid full bridge circuit is emphasized. The experiment test platform of 3kW is set up, and the hybrid full bridge structure is verified. In this paper, the influence of the parasitic parameters and the difference of the parameters on the leakage current in the non-transformer type inverter circuit based on the symmetric inductance structure is analyzed. In this paper, the model of the common mode resonant circuit related to the parasitic parameters of the system is given, and the disturbance of the high-frequency co-mode voltage and the parasitic parameters of the circuit are obtained. Based on the above-mentioned analysis, the common mode voltage and position structure of the high-frequency co-mode leakage current of the system is further eliminated, and the structure is optimized by using the existing full-bridge type symmetrical inductance configuration circuit, so that the common mode voltage in the existing topological scheme is effectively reduced, the high-frequency disturbance of the system is reduced, the parasitic parameter of the circuit is reduced, the system co-mode leakage is reduced, The effect of the current is verified by using the HERIC circuit based on the active voltage and the level of the active voltage. In this paper, an asymmetric inductor-based configuration with a flying-span capacitor junction is proposed. The circuit is formed by combining a three-level Buck structure of a flying capacitor and a power-frequency phase-changing structure, not only inherits the advantages of high conversion efficiency of the multi-level circuit and small filter inductance, but also retains the high-frequency co-mode leakage in the circuit of the power frequency switching structure the power of the current is reduced, the electricity is reduced, The DC input voltage of the circuit is based on the analysis of the working mode of the circuit. The design method of the parameters in the circuit is given from the angle of the conversion efficiency and the power density of the optimized circuit. Finally, using the above theory, combined with the network standard and the safety specification, the single-phase non-isolated photovoltaic grid-connected inverter product with high reliability and high conversion efficiency is designed, and the product has been proved by practice. The evaluation of the third-party organization has basically reached the work level.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM615;TM464
本文编号：2385484
[Abstract]:In recent years, the problems of global environmental pollution and energy shortage have been increasing, and the countries of the world have stepped up the development of supporting clean renewable energy from a strategic point of view. The solar photovoltaic power generation has received extensive attention due to its rich resources and high efficiency. With the deep development of the related technologies of the photovoltaic power generation industry, the cost of the photovoltaic power generation system is continuously reduced, and the total amount of the photovoltaic installation in the world continues to climb. The application of PV power generation technology has also entered a transition period driven by policy to market. However, the initial investment of the photovoltaic power generation system is high and the cost recovery period is long, so the system cost can be further reduced, the power generation efficiency and the reliability of the system can be improved, and the investment recovery period is shortened to become the most important problem in the photovoltaic power generation industry. In the household-type distributed photovoltaic grid-connected power generation system, the non-transformer type inverter is highly favored by the users and the integrator of the photovoltaic system because of the advantages of low cost and high conversion efficiency of the electric energy. in the transformer-free system, however, the parasitic capacitance of the grid-connected inverter and the photovoltaic cell panel and the power grid form a common-mode loop, The grid inverter system can not meet the requirements of the common mode leakage current limit in the network standard. In this paper, a research on the leakage current of the co-mode in a non-transformer type photovoltaic grid-connected system In this paper, the common mode leakage current suppression condition of the non-transformer type circuit is analyzed, and two types of single-phase topological structure with common mode leakage current suppression capability are obtained: the circuit structure based on the symmetric inductance configuration and the circuit junction based on the asymmetric inductance configuration The method of forming a single-phase inverter circuit with a common-mode leakage current suppression capability and an optimization method of the total-mode leakage current are explored from the two circuit structures, respectively. First, the thesis derives the hybrid system based on the symmetric inductance configuration structure from the high-performance HERIC circuit. Based on the analysis of the basic working mode of the hybrid full bridge circuit, it is proved that the circuit has a common mode leakage current suppression capability In this paper, the PWM control method of the hybrid full bridge circuit is given, and the work of the hybrid full bridge circuit under the PWM control strategy is analyzed. The influence of non-ideal factors such as the asymmetry of the filter inductance and the non-synchronization of the switch action on the model property of the circuit is discussed, and the model of the model is also given. The circuit characteristics of the hybrid full bridge circuit structure and other symmetrical inductance configuration circuits are compared, and the industry of the hybrid full bridge circuit is emphasized. The experiment test platform of 3kW is set up, and the hybrid full bridge structure is verified. In this paper, the influence of the parasitic parameters and the difference of the parameters on the leakage current in the non-transformer type inverter circuit based on the symmetric inductance structure is analyzed. In this paper, the model of the common mode resonant circuit related to the parasitic parameters of the system is given, and the disturbance of the high-frequency co-mode voltage and the parasitic parameters of the circuit are obtained. Based on the above-mentioned analysis, the common mode voltage and position structure of the high-frequency co-mode leakage current of the system is further eliminated, and the structure is optimized by using the existing full-bridge type symmetrical inductance configuration circuit, so that the common mode voltage in the existing topological scheme is effectively reduced, the high-frequency disturbance of the system is reduced, the parasitic parameter of the circuit is reduced, the system co-mode leakage is reduced, The effect of the current is verified by using the HERIC circuit based on the active voltage and the level of the active voltage. In this paper, an asymmetric inductor-based configuration with a flying-span capacitor junction is proposed. The circuit is formed by combining a three-level Buck structure of a flying capacitor and a power-frequency phase-changing structure, not only inherits the advantages of high conversion efficiency of the multi-level circuit and small filter inductance, but also retains the high-frequency co-mode leakage in the circuit of the power frequency switching structure the power of the current is reduced, the electricity is reduced, The DC input voltage of the circuit is based on the analysis of the working mode of the circuit. The design method of the parameters in the circuit is given from the angle of the conversion efficiency and the power density of the optimized circuit. Finally, using the above theory, combined with the network standard and the safety specification, the single-phase non-isolated photovoltaic grid-connected inverter product with high reliability and high conversion efficiency is designed, and the product has been proved by practice. The evaluation of the third-party organization has basically reached the work level.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM615;TM464
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