低压微网运行控制的下垂控制器研究与设计

发布时间：2018-11-01 11:32

【摘要】：随着电网规模的扩大,传统大电网集中供电难以适应用户多元化的供电需求,促使了分布式发电技术的发展。但由于分布式电源的随机性和不可控性,又限制了分布式电源的利用和使用效率。作为分布式电源的有效利用形式,微网既能充分利用分布式电源的优势,又能协调分布式发电和大电网之间的矛盾。微网的控制策略决定其在孤岛和并网模式下的运行情况,并影响运行模式切换的平滑性。因此,确定合适的控制策略是实现微网稳定运行的关键。首先,本文分析了下垂控制基本原理和微网的下垂控制特性,给出了三相电压型逆变器的数学模型及其LC滤波器参数的设计准则,依据逆变器的数学模型和设计准则分析了包含功率测量模块、下垂特性控制模块和电压电流双闭环控制模块的逆变器下垂控制器,并给出了下垂控制器在低压微网中的应用。其次,本文在微网对等控制体系下的运行模式基础上,给出了低压微网运行控制策略。在孤岛运行模式下,针对连接阻抗差异造成的功率分配不准确以及负荷变化引起的电压不稳定问题,给出了改善无功分配精度、提高电压稳定性的自调节改进下垂控制器设计；在模式切换状态下,给出了同步并网下垂控制器设计,通过调节微电网输出的电压使得微电网与大电网的电压幅值差、频率差和相角差满足并网要求,以实现微网在孤岛和并网两种模式之间的平滑切换。最后,在Matlab/Simulink环境下搭建了低压微网运行控制仿真系统,分别对微网孤岛模式运行、模式切换运行状态进行了仿真实验,仿真结果分析表明所提出的低压微网运行控制策略和所设计的自调节改进下垂控制器及同步并网下垂控制器的有效性。
[Abstract]:With the expansion of power grid scale, traditional centralized power supply in large power grid is difficult to adapt to the diversified power supply demand of users, which promotes the development of distributed generation technology. However, due to the randomness and uncontrollability of distributed power, the utilization and efficiency of distributed power are limited. As a form of efficient utilization of distributed generation, microgrid can not only make full use of the advantages of distributed generation, but also can coordinate the contradiction between distributed generation and large power grid. The control strategy of microgrid determines its operation in isolated island and grid-connected mode, and affects the smoothness of switching operation mode. Therefore, to determine the appropriate control strategy is the key to realize the stable operation of the microgrid. Firstly, the basic principle of droop control and the droop control characteristics of microgrid are analyzed, and the mathematical model of three-phase voltage source inverter and the design criteria of LC filter parameters are given. According to the mathematical model and design criterion of inverter, the droop controller of inverter including power measurement module, droop characteristic control module and voltage and current double closed loop control module is analyzed, and the application of droop controller in low voltage microgrid is given. Secondly, based on the operation mode of micro-grid peer-to-peer control system, a low-voltage microgrid operation control strategy is presented. In the isolated operation mode, aiming at the inaccurate power distribution caused by the difference of the connection impedance and the voltage instability caused by the load variation, a self-regulating improved sagging controller is designed to improve the reactive power distribution accuracy and increase the voltage stability. In the mode switching state, the design of synchronous grid-connected droop controller is presented. By adjusting the output voltage of microgrid, the voltage amplitude difference, frequency difference and phase angle difference between microgrid and large power grid can meet the requirements of grid-connected. In order to realize the smooth switching between island and grid-connected modes. Finally, the simulation system of low-voltage microgrid operation control is built in Matlab/Simulink environment, and the simulation experiments are carried out for the operation of isolated island mode and mode switching state of microgrid. The simulation results show the effectiveness of the proposed low-voltage microgrid operation control strategy and the self-tuning improved droop controller and synchronous grid-connected droop controller.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM732

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