低压微电网多源协调控制策略研究

发布时间：2018-12-08 15:00

【摘要】：微电网是集分布式电源、储能装置、能量转换装置、控制装置、监控保护装置、能量传输线路及负荷于一体的小型发电、配电及供电系统。而分布式电源通过逆变装置接入电网,充分利用分布式电源的优势和逆变装置的灵活可控为改善微电网系统的电能质量提供了条件。在低压微电网中采用下垂控制实现微源逆变器功率分配时造成电压跌落,如何实现逆变器功率的精确分配和电压稳定的均衡控制成为低压微电网稳定运行的关键问题。因此,本文研究了基于虚拟阻抗的下垂控制,在此基础上,利用基于分层控制的协调控制策略提高逆变器功率分配精度与电压稳定的均衡控制。首先,研究了微电网常用控制策略以及微电网接口逆变器中常用的控制方法。建立风力发电、光伏电池、储能蓄电池和燃料电池的数学模型,并利用MATLAB/Simulink仿真软件对其出力特性进行仿真分析。其次,分析逆变器功率传输特性,设计功率控制器和电压电流环控制器。针对低压微电网中逆变器输出功率的精确分配与电压稳定的均衡控制问题,提出基于虚拟阻抗的改进下垂控制策略,通过引入虚拟阻抗控制环可实现功率解耦,提高逆变器功率输出精度和电压稳定性。再次,针对孤岛过渡期间及孤岛模式下因微源逆变器测量环节的延时和微源响应速度慢而造成微电网系统电压跌落,改进燃料电池和储能电池的功率控制环,提出基于分层控制的联网和孤岛模式下微电网运行控制策略,保证系统暂态稳定性。最后,在MATLAB/Simulink仿真环境下对基于分层控制的联网和孤岛模式下的微电网运行控制策略进行仿真分析。仿真结果表明本文所提出的基于虚拟阻抗的改进下垂控制策略在功率精确分配与电压稳定的均衡控制中具有良好的控制效果,对低压微电网系统的暂态稳定性和电能质量的提高具有重要意义。
[Abstract]:Microgrid is a small power generation, distribution and power supply system that integrates distributed power generation, energy storage, energy conversion, control, monitoring and protection, energy transmission lines and loads. The power quality of microgrid system can be improved by fully utilizing the advantages of distributed power generation and the flexibility and controllability of inverter devices. Voltage drop is caused by droop control in low-voltage microgrid. How to realize accurate distribution of inverter power and balanced control of voltage stability has become a key problem in the stable operation of low-voltage microgrid. Therefore, the droop control based on virtual impedance is studied in this paper. On the basis of this, the coordinated control strategy based on hierarchical control is used to improve the power distribution accuracy and voltage stability equalization control of the inverter. Firstly, the common control strategies of microgrid and the common control methods of microgrid interface inverter are studied. The mathematical models of wind power generation, photovoltaic cell, energy storage battery and fuel cell are established, and their output characteristics are simulated and analyzed by MATLAB/Simulink simulation software. Secondly, the power transmission characteristics of the inverter are analyzed, and the power controller and the voltage current loop controller are designed. Aiming at the problem of accurate distribution of inverter output power and balanced control of voltage stability in low-voltage microgrid, an improved droop control strategy based on virtual impedance is proposed. Power decoupling can be realized by introducing virtual impedance control loop. Improve the power output accuracy and voltage stability of the inverter. Thirdly, in view of the delay of microsource inverter and the slow response speed of microsource inverter during the island transition period and in isolated island mode, the voltage drop of microgrid system is caused, so the power control loop of fuel cell and energy storage cell is improved. In order to ensure the transient stability of the system, a strategy of microgrid operation control based on hierarchical control is proposed in this paper, which is based on interconnection and islanding mode. Finally, the operation control strategy of microgrid based on hierarchical control and islanding mode is simulated and analyzed in MATLAB/Simulink simulation environment. The simulation results show that the proposed improved droop control strategy based on virtual impedance has a good control effect in the equalization control of accurate power distribution and voltage stability. It is of great significance to improve the transient stability and power quality of low voltage microgrid system.
【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM464;TM727

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