【作者】 张超；

【导师】 何湘宁；

【作者基本信息】 浙江大学 ， 电力电子与电力传动， 2006， 博士

【摘要】 随着经济全球化进程的加速和工业经济的迅猛发展，世界范围内的能源短缺和环境污染已成为制约人类社会可持续发展的两大重要因素。光伏发电因发电过程中无污染、无噪音、维护简单、无需生产原料等优点而逐步显示出其无比广阔的发展空间和应用前景。因此，大力发展光伏发电技术和产业已成为当务之急。本文以光伏并网发电系统为研究对象，对光伏并网发电系统中的最大功率点跟踪控制、孤岛效应的检测、交流光伏模块系统新型拓扑等问题进行了深入系统的研究。在此研究的基础上，分别提出了非对称模糊最大功率点跟踪控制和双模式最大功率点跟踪控制两种新的最大功率点跟踪控制方法、周期性扰动正反馈有源频率漂移孤岛检测方法和一种用于交流光伏模块系统的新型拓扑：BBHF逆变器。针对光伏发电系统中光伏器件的输出功率易受外部环境影响而降低了光伏发电系统效率的问题，本文提出了两种新的最大功率点跟踪控制方法：非对称模糊最大功率点跟踪控制和双模式最大功率点跟踪控制。这两种方法均能使光伏发电系统输出功率快速跟踪外部环境的变化，同时可有效消除或减弱光伏器件在最大功率点附近的功率振荡现象，从而提高了光伏器件的利用率。上述两种方法均通过实验得到了验证。光伏发电系统并网工作时，电网停电造成的孤岛效应会导致用电设备损坏和人身伤亡事故，因此必须及时检测出孤岛效应的发生并切断系统与电网的连接。针对孤岛效应检测中，有源频率漂移法检测盲区较大的缺陷，本文提出了周期扰动正反馈有源频率偏移法。通过仿真及实验验证，该方法在电网出现故障时，检测速度更快，具有更小的检测盲区，能够迅速切断电网与光伏发电系统的连接，从而避免孤岛效应造成的设备和人员损伤。为了验证以上所提方法的有效性和优越性，本文基于DSP设计了一套单相两级式光伏并网发电系统。该电路由最大功率点跟踪电路、逆变器、滤波电路、保护和控制电路构成。其具有独立运行和并网运行两种工作模式，可以根据用户的需要进行切换。实验结果表明：该电路运行可靠，保护功能完善，并在实验过程中为后续的研究工作积累了大量的实验数据和经验。最后，针对交流无损耗逆变器和反激式交流光伏模块系统存在系统运行过程中光伏器件最大功率点易受电路运行干扰的缺点，本文提出了一种用于交流光伏模块系统的新型逆变器拓扑结构：BBHF逆变器。实验表明：该电路不仅实现了最大功率点控制电路与后级逆变器的解耦，确保了光伏器件稳定工作在最大功率点，且电路中部分功率器件工作频率为工频，能够减少开关损耗，部分提高系统效率。更多还原

【Abstract】 In recent years, there has been an increase in the use of renewable energy due to the growing concern for the pollution caused by fossil-fuel-based energy. On-site power generation using sources like photovoltaic (PV) arrays can be used to reduce the dependence on energy from the grid as well as provide back up power for critical systems during grid outages.This thesis proposed a PV grid-connected power generation system that can be used in stand-alone mode and grid-connected mode, to convert the DC power output of the PV arrays to the more useful 220V AC. The operation and design of the various stages of the system are discussed. During the processes of developing PV energy generation system, maximum power point tracking, anti-islanding equipment, novel topology for AC photovoltaic module system and the control of inverter are researched. And some valuable results are obtained.In the first part of this paper, to extract more power from PV arrays, two novel MPPT methods are presented: asymmetric fuzzy maximum power point tracking (MPPT) method and two-mode maximum power point tracking method. Simulation and experimental results show that the PV power generation system has good steady state and transient characteristics with the control of the two proposed MPPT control methods.In the second part of this paper, the active frequency drift with periodical disturbance and positive feedback method is provided to detect islanding based on the active frequency drift (AFD) anti-islanding method. This new anti-islanding method can reduce the non-detection zone (NZD) and increase the speed of anti-islanding detection compare to the AFD method. In the third part of this paper, a PV grid-connected power generation system is designed based on the above work. It is composed of a MPPT circuit, an inverter, filter, control circuits and protection circuits. It can work under the stand-alone mode and the grid-connected mode according to the choice of user. The PV power generation system sets up a good base for the next work.At last, a novel topology for ACM( AC photovoltaic module) system is presented. The new topology consists of a BUCK-BOOST converter and a current source inverter. The BUCK-BOOST circuit implements maximum power point tracking of PV array well due to eliminateing the power perturbation from inverter. The current source inverter transforms this DC power into the 220V and 50Hz AC power at last. The effectiveness of the proposed inverter is confirmed experimentally and through simulation results.更多还原