【作者】 张秀青；

【导师】 杜少武；

【作者基本信息】 合肥工业大学 ， 电力电子与电力传动， 2008， 硕士

【摘要】 随着世界能源枯竭问题日趋严重,可再生能源的发展和应用倍受世界各国的重视。太阳能凭其可再生性和无污染性成为人类开发利用绿色可再生能源的焦点,正由补充型能源走向替代型能源,故光伏并网发电系统是太阳能利用的必然发展趋势。作为光伏并网发电系统的核心部分,逆变器越来越受到学术界和产业界的关注。目前,太阳能电池的电压等级不高,若与高压电网并网,则要增加变压器、DC/DC变换器等中间升压环节,使得并网系统结构复杂、系统可靠性降低。后来出现的级联逆变器可以将太阳能发出的电能直接并于高压电网,从而简化并网系统结构、提高系统可靠性。但是目前级联逆变器存在电路拓扑结构复杂、调制不方便等问题。脉冲阶梯调制(PSM)技术是阶梯调制(SM)技术和脉宽调制(PWM)技术相结合的一种调制技术,具有电路简单、控制方便等优点,是高压大功率电源系统中重要的调制技术。基于PSM技术的变换器具有更高的连续可调的输出电压、更大的输出功率、高可靠性、高效率等众多优点。若能将PSM技术应用于级联逆变器,则可以解决上述问题。本文任务是将PSM技术应用于级联逆变器,并将PSM级联逆变器应用于光伏并网系统。本人主要工作:一、详细阐述PSM级联逆变器的工作原理和控制方法,在MATLAB/SIMULINK环境下设计其仿真电路,通过仿真验证其原理及控制方法的可行性;二、研究PSM级联逆变器光伏并网系统的控制策略,在MATLAB/SIMULINK环境下设计该并网系统的仿真电路,通过系统仿真验证了其控制策略的可行性和优越性。更多还原

【Abstract】 With the world’s energy sources drying up day by day, the development and application of the reproducible energy sources get much world attention. Solar energy became the focus of human development and utilization new energy sources for its renewable and pollution-free. Now, solar energy is tending towards substitute sources from complementary sources, so photovoltaic grid-connected power generation system is the inevitable trend of using solar energy. As its hard core, inverter more and more arrests academe’s and industry’s attention. At present, voltage scale of solar cell isn’t high enough, so it must add some middle taches such as transformer and DC/DC convertor etc in the PV grid-connected system. It makes the system’s structure complicated and its reliability lower. Cascaded inverter can directly connect PV cell and high grid-connected. The structure of system was simplified and its reliability was heightened. However, now the structure of Cascaded inverter is complex and its modulation method is inconvenience.The pulse step modulation (PSM) technology is the combination of the pulse width modulation (PWM) and the step modulation (SM). It is an important technology which is used high-voltage, high-power switching power supply system. If the PSM technology can be used in cascaded inverter, the above problem will be resolved.This paper’s main tasks are operating the PSM technology to cascaded inverter and making the PSM cascaded inverter applied to PV grid-connected system. The main works as follows: Firstly, the principle and the control method of the PSM cascaded inverter are expatiated and analyzed. Secondly, the control policy of the PV grid-connected system based on PSM cascaded inverter is researched and the simulation circuit of the system is designed under MATALEB/SIMULINK circumstance. At last, the advantages of the PSM cascaded inverter and the new system is verified on the result of simulation.更多还原