微电网并网与孤岛运行模式切换的研究.doc

摘 要 摘 要 太阳能、风能、潮汐能和地热能等清洁、廉价且无污染的可再生能源的开发和利用日益受到人们的重视，并且为了提高电能的安全性、可靠性、经济性以及灵活性等方面特性，促使了以可再生能源发电为主的分布式发电技术的发展。合理有效利用分布式电源的关键技术是如何将分布式电源与大电网并网发电，大量的分布式电源并网对大电网的安全可靠性带来了很大的影响。微电网作为一种能很好发挥分布式发电潜能的组织形式被提出，微电网是将分布式电源和负荷作为一个整体，形成可控的、既可并网运行也可以孤岛运行的小电网。微电网作为超高压、远距离、大电网供电模式的补充，代表着电力系统新的发展方向。 本文建立以逆变器为微电源的微电网模型，提出针对微电网独立和并网运行两种模式下，微电源的相应控制方法和策略，重点比较了并网 PQ 控制，单机孤岛 V/f 控制、多机孤岛下垂控制的效果，并在微电网模型中实现孤岛检测方法。 建立微电网分别在并网和独立运行模式下的小信号模型，采用特征值分析方法分析各参数对其稳定性的影响，并重点比较了微电网运行模式切换前后的特征值分布变化规律，据此提出切换的相应控制策略。 最后利用 MATLAB/simulink 软件对微电网进行建模，并实现并网和孤岛及两种模型的切换几种情况下逆变器控制策略，研究微电网运行模式切换过程中的动态特性规律，对切换控制器进行优化，减小切换过程中的暂态振荡。并在此基础上总结微电网中各参数对微电网平稳切换所造成的影响，针对不能平稳过渡的情况提出解决方案。关键词：微电网；小信号分析；平滑切换 I Abstract Abstract As more and more attention has been paid to solar wind tidal geothermalenergy and other clean cheap and pollution-free renewable energy ‘s developmentand utilization and in order to enhance energy security reliability economy andflexibility as well the renewable energy based distributed generation technologies hasbeen prompted. The key technology to rational and effective use of distributed powersupply is these distributed power how to cooperation with bulk power grid the safetyand reliability of large power grid is influence by the large number of distributedpower. Micro-grid as a distributed generation can play a very good potential forms oforganization have been proposed it’s a distributed power supply and load as a wholethe formation of controllable and can run the network also run a small island grid.Micro-grid as a high pressure long distance bulk power supply mode of thesupplement represents a new direction power system. This paper establish a micro-grid model based on inverter according to the twomodes of the micro-grid the grid-connected and the autonomous modes proposedcontrol methods and strategies mainly compares the PQ controlV/f control and droopcontrol and implement the islanding detection method in the model. Establish the small signal model of the two modes analysis the stability of t