【作者】 陈文砚；

【导师】 李林川；

【作者基本信息】 天津大学 ， 电力系统及其自动化， 2010， 硕士

【摘要】 分布式发电代表着21世纪电力能源的发展方向,它可以增加系统的供电能力、降低对环境的污染、提高电力系统的可靠性和经济性。研究分布式发电的运行技术和改善其电能质量具有重要的实际意义。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,称为微电网。微网的引入既补充了电网的供电模式,也给电力系统带来了其它问题,如:分布式电源一般需要通过逆变器和变压器接入电网,逆变器的接入会向配电网引入大量谐波;微电源本身也会造成如电压波动、功率因数偏低等电能质量问题。微网中如果存在无功需求较大的微源或者负荷,还需要实现无功的就地补偿,以保持电压的稳定。根据分布式电源本身和负荷对供电的要求,必须对微网采取一定的改善电能质量的措施。有源电力滤波器(APF)是配网中常见的滤波和无功补偿装置,一般采用瞬时无功检测法检测谐波电流,APF可以实现谐波和无功电流的动态跟踪和补偿,反应速度快,滤波效果好。APF控制比较复杂,投资较大,且有容量限制,在无功需求量大的系统中如果完全使用APF作为补偿器件,从经济性角度考虑是不太合适的。SVC作为配网中常用的无功补偿装置,能够快速、平滑地调节无功功率,满足动态无功补偿的需要,具有价格低廉、补偿容量大的优势。本文考虑在微网中应用APF和SVC联合系统,APF装设在分布式电源出口进行滤波并进行小容量的无功电流补偿,SVC装设在负荷侧实现大容量无功的就地补偿。APF可以实现快速跟踪补偿,弥补SVC对快速变化功率反应较慢的缺点。SVC可以弥补APF补偿容量不足的缺点,两者互为补充。采用Matlab-Simulink搭建了各种电力器件和电网系统的模型,分别对联网模式和孤岛模式下的控制方法进行了仿真,实现了各自的有效控制。在此基础上添加APF和SVC联合系统对电能质量进行改善,仿真证明APF+SVC联合系统能很好的改善电能质量。更多还原

【Abstract】 Distributed generation represents the development direction of the electric energy in the 21st century. Distributed generation can increase the supply ability of the power system; reduce pollution to the environment; improve the reliability and efficiency of the power system. Studies of the distributed power generation technology and improving DG’s electric power quality have important practical significance.Micro electric gird is a system including the distributed generation and the load as a unity. It’s a controllable system which can be operated both in the interconnected mode and islanding mode. The introduction of the Micro gird supplement the modes of operation of the power grid, but at the same time, it brings a lot of problems, for example, DGs usually access to the grid through inverters and transforms, the inset of the inverters bring plenty of harmonics to the distributing grid; The DG itself can also cause problems such as voltage fluctuation and low power factor. If there exists Micro source or load which has big reactive power demands in the Micro grid, the on-spot compensation of the reactive power is needed to keep the voltage’s stability. According to the demands of the distributed generations themselves and the loads, measures must be taken to improve the electric quality of the Micro grid.APF is a devices widely used in the distributing gird for harmonic filtering and reactive power compensation. It usually adopts the Instantaneous Reactive Power Theory for harmonic detection.APF can realize the dynamic tracking and compensation of the harmonic and reactive current; it has fine filtering effect due to its quick response. The controlling of APF is relatively complex. Which more, the investment of APF is often expensive while comparing with its capacity. So it’s not a suitable choice from the economic consideration if we use APF as the only compensation device in the power grid which has big demands for reactive power compensation.SVC is a common device for reactive power compensation in the distributing grid which has superior in low price and big capacity. It can adjust the reactive power quickly and smoothly, satisfy the need of dynamic reactive power compensation. In this paper, an APF-SVC combination system is introduced in the Micro gird, APF is installed at the export of the DG to fulfill the function of harmonic filtering and compensation of small volume of reactive current. SVC is installed at the side of the load for on-spot reactive power compensation. APF’s quick response can offset the weakness that SVC has slow response to rapid-changing power needs while SVC can make up for the defect that APF has small compensation capacity. Matlab– Simulink is used to build the modes of the electrical devices and power system. Both the control methods in networking mode and island mode are simulated and realize their effective control. On the basis, APF-SVC combination system is introduced to improve the electric quality. Simulation results prove APF-SVC combination system can improve power quality commendably.更多还原