共直流母线型模块化光伏并网发电系统相关关键技术研究

发布时间：2018-04-06 01:30

本文选题：光伏　切入点：模块化　出处：《浙江大学》2014年博士论文

【摘要】：近年来,为缓解能源危机和环境污染,太阳能、风能等清洁可再生能源得到了广泛的应用。在光伏发电系统中,为了提高系统转换效率和可靠性,模块化结构受到越来越多的青睐并成为学术界的研究热点。论文对共直流母线型的模块化光伏并网发电系统的相关关键技术进行了较为深入的研究。针对系统前级的直流模块,采用内置变压器和内置变压器倍压单元实现高增益高效率变换；针对系统后级的逆变模块并联,采用线性功率控制改善系统的动态性能,提高系统的稳定性和可靠性。首先,本文将变压器嵌入传统的交错并联Boost变流器中,形成非隔离型高增益变流器。通过对隔离型变流器中常用的整流结构进行重构,演绎出内置变压器结构作为电压增益拓展单元,实现了变流器电压增益的大幅提升,避免了开关管工作在极限占空比状态,同时降低了开关管的电压应力,可采用低导通电阻、高性能开关管降低导通损耗。采用有源箝位电路有效的吸收内置变压器漏感的能量,抑制开关管的关断电压尖峰。主开关管和箝位开关管均实现了零电压软开关,减小了开关损耗,提升了效率。内置变压器的漏感抑制了输出二极管的反向恢复电流,减小了反向恢复损耗,降低了EMI噪声。变流器的输入电感以及交错并联结构有效降低了输入电流纹波,减小对输入侧电解电容的冲击。此外,本文总结了内置变压器结构的形成规律和升压机理,据此可演绎出一系列含内置变压器结构的非隔离型高增益变流器,为新型高增益变流器的生成提供了新的方法。其次,本文将倍压整流电路与内置变压器结合,形成内置变压器倍压单元作为电压增益拓展单元,实现变流器电压增益的进一步提升。改进后的变流器进一步降低了输出二极管的电压应力,同时电压增益更高,开关管的电压应力更低,使该变流器更适合应用于高增益变换场合。为了简化驱动电路,采用无源箝位方案,提高了变流器的可靠性。开关管实现了零电流开通,箝位二极管实现了自然关断,降低了开关损耗,提高了效率。再次,为了实现逆变模块并联运行,本文设计了50kW光伏并网逆变模块。模块采用T型三电平拓扑,提高了效率和可靠性。为了设计模块控制系统,建立了T型三电平光伏并网逆变器小信号模型,进而得到控制系统框图,设计了关键控制参数。此外,模块采用无功功率扰动作为主动孤岛检测方案。实验结果显示,逆变模块具有良好的稳态性能和动态性能,并网电流各次谐波均符合国家标准,主动孤岛检测快速有效。模块结构采用分层设计,散热效率高。整个系统仅有一个并网接口,方便模块的安装和更换。最后,本文设计了光伏并网逆变模块并联系统。该系统采用层次控制架构,各个模块地位均等。模块控制输出电流实现并网发电,处于控制系统上层的中央控制器控制直流母线电压。论文采用线性功率控制方案,将直流母线电压信息引入到模块电流控制环的参考中,使逆变模块由恒功率特性变为根据母线电压变化的线性功率特性。当母线电压变化时,逆变模块可快速调整输出电流,提高了系统的动态性能,抑制了功率剧烈变化时母线电压的波动,降低了通讯速率对系统的影响。即使通讯线故障,系统仍可维持运行,提高了稳定性和可靠性。此外,设计了100kW模块化光伏并网逆变器工程样机,样机性能良好,运行稳定,体现了线性功率控制的工业应用价值。论文对共直流母线型的模块化光伏并网发电系统相关关键技术的研究有助于推动光伏发电的发展。
[Abstract]:In recent years, in order to alleviate the energy crisis and environmental pollution, solar, wind and other renewable and clean energy. It has been widely applied in photovoltaic power generation system, in order to improve the system efficiency and reliability, the modular structure has attracted more and more attention and become a hot research topic in academic circles. The key technology of common DC bus type the modular photovoltaic power generation system is studied. According to the DC module system level, using the built-in transformer and voltage doubling transformer unit built-in high gain and high efficiency transformation; for the parallel inverter modules level system, the dynamic performance of the linear power control to improve the system, improve the stability and reliability of the system.
First of all, the transformer into the traditional interleaved Boost converter, forming a non isolated high step-up converter. Through the reconstruction of the rectifier structure commonly isolated converter, deduce the built-in transformer structure as the voltage gain expansion unit to achieve a significantly improved converter voltage gain, avoid switch work in the limit the duty ratio, and reduce the voltage stress of the switches, with low resistance, high performance switch tube to reduce the conduction loss. The active clamp circuit can effectively absorb built-in transformer leakage inductance energy suppression switch turn off voltage spike. The main switch and clamp switch tube to realize zero voltage soft switching, the switching loss is reduced, to enhance the efficiency. With the leakage inductance of the transformer suppresses the output diode reverse recovery current, reduce the reverse recovery loss, low noise EMI The sound input inductor converter. And the interleaved structure effectively reduces the input current ripple, reduce the input side of the electrolytic capacitor impact. In addition, this paper summarizes the formation rules and boost mechanism built in transformer structure, which can deduce a series with built-in transformer structure of non isolated high step-up converter, provides a new a new method for the generation of high gain converter.
Secondly, this paper will combine with the built-in voltage doubler rectifier circuit transformer, transformer voltage unit as forming the built-in voltage gain expansion unit, further improve the converter voltage gain of the converter. The improved further reduces the voltage stress of the output diode, and higher voltage gain, lower voltage stress of the switches, the converter more suitable for high gain conversion applications. In order to simplify the drive circuit, the scheme of passive clamp, improves the converter reliability. Switches realize zero current turn-on, clamping diodes achieve natural shutdown, reduces the switching loss and improve efficiency.
Again, in order to realize the parallel operation of inverter module, this paper introduces the design of 50kW photovoltaic grid connected inverter module. The module uses the T type three level topology, improves efficiency and reliability. In order to design the module control system, set up three level photovoltaic grid connected inverter T small signal model, and then get the block diagram of control system is designed. In addition, the key control parameters that module by perturbation as the active islanding detection scheme of reactive power. The experimental results show that the inverter has good steady-state performance and dynamic performance, the grid current harmonics are in line with national standards, active islanding detection is fast and efficient. The module structure of the hierarchical design, high efficiency of heat dissipation. The entire system is only a grid interface, installation and convenient replacement module.
Finally, this paper designed the parallel photovoltaic grid connected inverter module system. The system uses a hierarchical control architecture, equal status. Each module module to control the output current of the realization of the grid, at the central controller to control the DC bus voltage control system. This paper adopts linear upper power control scheme, the introduction of information to the DC bus voltage module current control loop in reference, the inverter module is composed of constant power characteristic into linear power according to the characteristics of bus voltage change. When the bus voltage changes, inverter module can quickly adjust the output current, improve the dynamic performance of the system, the bus voltage fluctuation suppressing power dramatically, reduce the impact on the system. Even if the communication rate of communication line fault, system can still maintain the operation, improve the stability and reliability. In addition, the design of the 100kW modular photovoltaic inverter prototype The performance of the prototype is good and the operation is stable, which embodies the industrial application value of linear power control.
The research on the key technologies related to the common DC bus type modular photovoltaic grid connected power generation system will help to promote the development of photovoltaic power generation.

【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】：TM46;TM615

【参考文献】