【作者】 耿乙文；

【导师】 伍小杰；

【作者基本信息】 中国矿业大学 ， 电力电子与电力传动， 2014， 博士

【摘要】 近年来，在人类社会科技与经济高速发展的过程中，不可再生能源的大量使用带来了严重的环境污染和生态恶化的问题，严重地影响了社会的发展和人类的健康，太阳能、潮汐能和风能等可再生能源的利用引起了广泛的重视。光伏发电系统是太阳能利用的重要形式，而且具有有源滤波功能的光伏发电（PhotovoltaicPower Generation and Active Filter，PV-AF）系统拓宽了光伏发电系统的功能，在实现向电网注入有功电能的同时，还能有效地抑制电网中的谐波等问题，具有广阔的发展及应用前景。本文针对接入三相四线制低压电网的四桥臂PV-AF系统关键技术进行了研究。在分析基于保守功率理论（Conservative Power Theory，CPT）的谐波电流检测方法的基础上，针对电网电压畸变的情况，提出了一种基于电网电压消谐的改进型CPT谐波电流检测方法，通过提取公共连接点电压中的基波成分，抑制电压中谐波成分对补偿电流计算的影响。仿真和实验验证了所提方法的合理性及可行性。最大功率点跟踪（Maximum Power Point Tracking，MPPT）技术是提高能量转换的关键环节，决定了四桥臂PV-AF系统的工作效率，本文对各种MPPT方法进行了比较，对扰动观察法在最大功率点（Maximum Power Point，MPP）附近的振荡进行了分析，研究了系统工作点处于MPP附近的判断方法，提出了一种扰动观察法与恒定电压法相结合的改进型MPPT新方法。实验和仿真表明该方法能够准确快速地跟踪最大功率点。四桥臂PV-AF系统的控制策略中，电压外环用于直流侧电压的控制和最大功率点的跟踪，电流内环用于跟踪基波并网电流和电网中谐波电流指令，电流环控制性能至关重要，本文提出了一种基于PI和重复H_∞控制的复合控制器的电流环控制策略，PI控制环节保证系统的动态性能，内模环节使得稳态误差更小，鲁棒控制环节有效增强了系统的抗干扰性能，在连续域对复合控制器参数进行设计，通过离散化完成控制器的数字实现，并且在离散域中研究了离散化对系统性能的影响。在不同情况下对提出的复合控制器进行了实验和仿真验证，结果表明系统具有良好的动态性能、更小的稳态误差和优良的鲁棒性，具有穿越低电压区域的能力。针对系统中存在的负阻抗将会影响系统稳定性的问题，本文研究了基于小信号模型的四桥臂PV-AF系统阻抗建模，对不同控制策略下参数变化对系统阻抗特性的影响进行了比较研究。验证了优化后的复合控制器参数，在保证系统性能的前提下，能够有效地减小负阻抗对系统稳定性的影响。主电路参数是影响四桥臂PV-AF系统性能的关键因素之一，本文对四桥臂PV-AF系统主电路参数进行了设计，对器件进行了选型，搭建了5kVA三相四桥臂PV-AF系统实验平台。更多还原

【Abstract】 In recent years, with the rapid development of technology and economy, themass utilization of non-renewable energy has brought severe problems ofenvironmental pollution and ecological deterioration, which has a negative impact onthe social development and human health. Thus, much attention has been paid to therenewable energy, such as solar energy, tidal energy, wind energy, etc. Photovoltaic(PV) power generation system is an important form of utilization of solar energy andone kind of distributed power generation systems. Besides, photovoltaic powergeneration and active filter (PV-AF) system broadens the function of PV powergeneration system. As the active power is injected into the grid, harmonics in the gridcan be suppressed effectively. Thus PV-AF system has broad development andapplication prospect. In this dissertation, key technology for three-phase four-wirelow-voltage four-leg PV-AF system has been studied.Based on the analysis of conservative power theory (CPT) harmonic currentdetection method, an improved CPT harmonic current detection method based on gridvoltage harmonic elimination has been proposed in distorted grid voltage conditions,by extracting the fundamental component of voltage at the point of common coupling(PCC), which inhibits the influence of voltage harmonic components on the currentcalculation. Simulation and experimental results verify the rationality and feasibilityof the proposed method.The maximum power point tracking (MPPT) technique is the key to improve theenergy conversion, maintaining the operation efficiency of four-leg PV-AF system. Inthis dissertation, different kinds of MPPT methods are compared. The oscillationnearby the maximum power point (MPP) is analyzed while adopting the perturb andobserve method. The method judging whether the MPP is nearby the MPP has beenstudied and an improved MPPT method has been proposed. Experiments andsimulation show that the proposed method can track the MPP quickly and accurately.As for the control strategy of four-leg PV-AF system, the outer voltage loop isadopted for controlling DC voltage and tracking the MPP. The inner current loop isused to track the fundamental grid current and the harmonic current reference value,which is vital to the entire system controlling. In this dissertation, a novel current loopcontrol strategy based on compound controller with PI (Proportional Integral)controller and H_∞repetitive controller has been proposed. PI controller ensures the dynamic performance of the system. The internal model makes smaller steady-stateerror. Robust control effectively enhances the anti-interference performance of system.The parameters for the compound controller have been designed and the digitalimplementation for the controller has been conducted by discretization. The influenceof the discretization on the system performance has been studied in the discretedomain. Simulation and experiments have been implemented on the proposedcompound controller under different conditions. The results show that the systemowns decent dynamic performance, smaller steady-state error, good robustness andlow voltage ride through ability.For that the existence of negative impedance in the system will affect thestability of the system, the small-signal impedance modeling for the four-leg PV-AFsystem has been studied. Via different control strategies, the research about theinfluence of impedance mpedance characteristics on system stability has beenconducted comparatively. On the premise of guaranteeing the system performance,the impact of the negative impedance on system stability has been reduced throughthe optimization of the controller parameters, which has been verified.The main circuit parameters are the key factors affecting the performance of thefour-leg PV-AF system. In this dissertation, the parameters for the main circuit offour-leg PV-AF system have been designed. The devices are selected. Experimentalplatform of5kVA three-phase four-leg PV-AF system have been set up.更多还原