孤岛微电网下垂控制策略研究

发布时间：2018-04-20 21:45

本文选题：微电网 + 下垂控制　；参考：《南京师范大学》2017年硕士论文

【摘要】：微电网发电系统不仅可以为我们提供清洁、经济和可靠的能源,还可以缓解传统能源的短缺问题。作为微电网的一种重要应用形式,孤岛微电网具有很强的兼容性和环境适应性,可在多种地貌和环境下使用,对于减少污染排放、降低偏远地区的发电用电成本和改善电能质量有着积极作用。下垂控制作为孤岛微电网的一种重要控制策略,因其具有不依赖通信系统的功率调控能力和“即插即用”的优点而被广泛使用。然而,在下垂控制下的孤岛微电网中,实际的线路阻抗多为阻感特性,会造成功率耦合问题。线路阻抗和负荷波动还会造成电压跌落和频率突变等问题,难以实现良好的控制效果。本文主要研究在低压孤岛微电网环境下,下垂控制微电源存在的功率耦合、电压跌落和频率突变问题。(1)针对目前微电网的几种控制策略,在对比分析了下垂控制策略的孤岛运行优势后,又对传统下垂控制策略的局限性展开了分析。基于下垂控制原理,设计搭建了孤岛微电网下垂控制Matlab/Simulink仿真模型。(2)针对孤岛微电网线路阻抗引起的下垂控制功率耦合问题,在传统下垂控制方法的基础上引入虚拟阻抗环节。计算分析得到了虚拟阻抗的取值边界条件,进而实现下垂控制微电源输出功率的解耦控制。(3)针对孤岛微电网下垂控制中无功负荷和虚拟阻抗引起的电压跌落现象,提出了一种电压反馈控制方法。当系统电压发生跌落时,反馈环节能不借助通信模块快速调节电压使其恢复到额定值附近并维持稳定。(4)针对孤岛微电网下垂控制中有功负荷波动引起的频率突变问题,提出了一种动态惯性控制方法。通过模拟同步发电机转子的惯性特性,根据不同的负荷容量,动态调节惯性系数,可以有效抑制系统频率突变,给予低频减载或保护装置充分的响应时间来维持频率稳定。
[Abstract]:Microgrid power generation system can not only provide us with clean, economical and reliable energy, but also alleviate the shortage of traditional energy. As an important application form of microgrid, island microgrid has strong compatibility and environmental adaptability, and can be used in many kinds of geomorphology and environment. Reducing the cost of power generation and improving power quality in remote areas has a positive effect. As an important control strategy of isolated island microgrid, droop control is widely used because of its power control ability independent of communication system and "plug and play". However, in the isolated island microgrid with droop control, the actual line impedance is mostly resistive, which will lead to power coupling problem. The line impedance and load fluctuation can also cause voltage drop and frequency mutation, so it is difficult to achieve good control effect. In this paper, the problems of power coupling, voltage drop and frequency mutation in droop control micropower supply are studied in the environment of low-voltage isolated microgrid. After comparing and analyzing the island operation advantage of droop control strategy, the limitation of traditional droop control strategy is analyzed. Based on the droop control principle, the Matlab/Simulink simulation model of droop control of isolated island microgrid is designed and built. Aiming at the power coupling problem caused by line impedance of isolated island microgrid, virtual impedance link is introduced on the basis of traditional droop control method. The boundary condition of virtual impedance is obtained, and then the decoupling control of output power of droop control micro-power supply is realized. The voltage drop caused by reactive power load and virtual impedance in droop control of isolated microgrid is analyzed. A voltage feedback control method is proposed. When the voltage of the system falls, the feedback link can quickly adjust the voltage to near the rated value without the help of the communication module and maintain stability. 4) aiming at the frequency abrupt change caused by the active power load fluctuation in the sagging control of the island microgrid. A dynamic inertial control method is proposed. By simulating the inertial characteristics of the synchronous generator rotor and dynamically adjusting the inertial coefficient according to different load capacity, the frequency abrupt change of the system can be effectively suppressed, and the frequency stability can be maintained by giving the low frequency load reduction or sufficient response time of the protection device.
【学位授予单位】：南京师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM727

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