【作者】 孙东森；

【导师】 葛宝明；

【作者基本信息】 北京交通大学 ， 电气工程， 2013， 博士

【摘要】 太阳能光伏发电清洁、环保,是最具前景的新能源之一。而功率变换器则是光伏发电系统中的关键部件,其可靠性、运行效率以及制作成本对整个光伏发电系统至关重要。由于传统的单级式或两级式功率变换器在光伏发电应用中存在着不足,众多学者将研究目光投向了近年来提出的Z源逆变器(Z-Source Inverter,ZSI)和Quasi-Z源逆变器(Quasi-Z Source Inverter, qZSI),以及低谐波高效率的级联多电平逆变器(Cascade Multilevel Inverter, CMI)。本文根据研究现状,提出了三种新型逆变器拓扑,并将其应用于光伏发电系统,对其基本理论进行研究,并提出了相应的控制策略。具体如下：首先,结合光伏发电的特点以及用户的需求,提出了适用于光伏发电系统的储能型qZSI (Energy Stored qZSI, ES-qZSI)。对ES-qZSI进行数学建模,详细分析了电路中各状态变量以及各功率的关系。将ES-qZSI分别应用于独立光伏发电系统以及并网光伏发电系统,并研究了相应的控制策略。特别地,针对系统中的储能电池,本文提出了储能电池能量管理控制策略来确保储能电池的安全工作。其次,鉴于qZSI、ES-qZSI以及CMI的优点,提出了qZS级联多电平逆变器(qZS-CMI)和储能型qZS级联多电平逆变器(Energy Stored qZS-CMI, ES-qZS-CMI),并将这两种逆变器分别应用于光伏发电系统中。该部分研究主要包括以下几个方面：针对qZS-CMI及其光伏发电系统,研究了其基本模块—ZSI模块。文中考虑2倍频分量对qZSI模块进行了数学建模,首次推导得出了精确计算系统状态变量2倍频分量的数学公式。以此为基础,分析了系统状态变量2倍频分量随qZS网络参数的变化规律,提出了抑制2倍频纹波的qZS网络参数设计方法。详细分析了qZSI模块中各器件的工作状态、换流过程以及导通电流,计算了qZSI模块的功率损耗以及运行效率。研究了qZSI模块的光伏发电控制策略,采用波特图法对系统中各控制器的参数进行了整定。该部分研究为此类qZS-CMI的参数设计、器件选取提供了重要依据。针对qZS-CMI及其光伏发电系统,提出了该系统的控制方法,既可以实现对光伏电池的分布式MPPT控制,又可以确保每个模块拥有相同的直流母线电压,同时整功率因数并网。针对ES-qZS-CMI及其光伏发电系统,提出了该系统的控制方法,既可以实现对光伏电池的分布式MPPT控制,又可以保证各模块输出功率平衡,而且可以满足用户／电网需求灵活地提供负载／并网功率,平抑PV功率的波动。另外,分别研制了储能型qZS光伏发电系统样机、qZS级联多电平光伏发电系统样机以及储能型qZS级联多电平光伏发电系统样机,并对各样机进行了实验测试。实验结果验证了所提出的三种新型光伏逆变器及其光伏发电系统。更多还原

【Abstract】 Photovoltaic (PV) power generation is considered to be one of the most prospective renewable energies due to its pollution-free and environmental-protective characteristic. The power converter is a critical component in the PV power generation system, and its reliability, operating efficiency, and cost are significant for the whole system. Due to the shortcomings of the conventional single-stage or two-stage converters employed in PV systems, more and more researchers focus on the newly proposed Z-Source inverter (ZSI)/Quasi-Z Source inverter (qZSI) and the low harmonic high efficiency cascade multilevel inverter (CMI). According to the research status the dissertation proposes three novel inverter topologies, and applies them in the PV power generation system. Then the basic theory is studied and the control schemes of the proposed inverters when applied in PV system are proposed. The details are as follows:Firstly, considering the characteristic of solar energy and the users’demand, the dissertation proposes an energy-stored qZSI (ES-qZSI) for PV system. The mathematical model of the ES-qZSI is built and the relationship among the system state variables and powers is established. The ES-qZSI can be applied to stand-alone PV system and the grid-tie PV system respectively, and the corresponding control scheme for two systems are investigated. Furthermore, an energy management control scheme is proposed to control the system while taking into account battery safety.Secondly, in view of the advantages of qZSI, ES-qZSI and CMI, the dissertation proposes the qZS cascade multilevel inverter (qZS-CMI) and energy-stored qZS cascade multilevel inverter (ES-qZS-CMI), and then applies them to PV system. The investigation mainly includes the following aspects:For qZS-CMI, qZSI module which is the basic module to make up the cascade multilevel PV system is studied in detail. The dissertation proposes the mathematic model to calculate the2ω ripple component for system state variables accurately. Moreover, the relationship between the2ω ripple and the qZS network parameters is investigated, and the qZS network parameters selection method to limit2ω ripple is proposed. Also, the operating states, the power loss and the operating efficiency of qZSI module are presented in detail. Detailed study on the control strategy of qZSI module based PV system is carried out, and the controller parameters are obtained by using bode plots method. The work will provide important guidance of the parameter design and the device selection for this type cascade multilevel inverters.For qZS cascade multilevel PV power generation system, the control strategy is proposed. With the control strategy, the qZS cascade multilevel PV system can achieve distributed maximum power point tracking (MPPT), balanced DC-link voltage for each module, and the unity power factor operation.For ES-qZS cascade multilevel PV power generation system, the dissertation also proposes the control strategy, with which the system not only can balance the module power difference automatically, but also can satisfy the load/grid demand flexibly, except for the distributed MPPT.Finally, the prototype of ES-qZS PV system, the qZS cascade multilevel PV system, and the ES-qZS cascade multilevel PV system are set up and tested in the lab. Experimental results verify the proposed inverters and their PV systems.更多还原