交流微电网运行控制方法研究

发布时间：2018-03-06 13:14

本文选题：微电网　切入点：联网模式　出处：《长沙理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着能源问题和环境问题的日益突出,开发并充分利用清洁能源已经成为世界各国和社会可持续发展的重要战略。微电网能够减轻分布式发电对电网的冲击与不良影响,使分布式发电的效益和价值得到充分利用。微电网的关键技术之一就是运行控制,灵活多变的运行模式是微电网实现各种经济技术优势的前提。微电网存在联网运行模式和孤岛运行模式,本文将分两个层面对微电网运行控制策略展开研究。在微电源控制策略上,首先将微电源按功率输出稳定与否分为间歇型微源和可控型微源,对分布式微源的逆变器直流侧进行简化,着重研究逆变器控制策略,并建立起三相电压源型逆变器的数学模型。其次设计了电流内环控制器,深入分析了微电源逆变器的三种控制方式,即PQ控制、下垂控制以及V-f控制,表明在联网运行时改变PQ控制的参考功率可以实现公共连接点的潮流控制。孤岛运行模式下,通过下垂控制和V-f控制两种控制的协调配合可以实现微电网电压和频率的稳定,并针对下垂控制中的下垂系数进行改进,使下垂系数随微电网电压和频率动态变化,改进的下垂控制可以使系统出现功率缺额时,微电网的电压和频率下降幅度变小。最后通过设计预同步控制单元作用在下垂控制和V-f控制上实现孤岛运行模式向联网运行模式的切换。在微电网多电源协调控制策略上,分析了主从控制和对等控制。可知对等控制简单可靠、容易实现,当运行模式变化时不需要改变微源的控制方式,但是不能保证电压和频率的稳定性。主从控制能够支撑微网电压和频率,但是在运行模式变化时都需要改变主控微源的控制方式。因此本文提出一种主从和对等相结合的综合控制方法,该方法不仅可以实现电压和频率的稳定,而且还能减少微电源控制方式的切换次数,降低了控制方式切换失败的可能性,在一定程度上提高了微电网运行的可靠性。通过在微电源控制策略和微电网多电源协调控制策略上的相互配合,能够保证微电网在联网运行、孤岛运行以及两种运行模式之间相互切换过程中的电压和频率的稳定,有效减少微电网运行模式变化时主控微源的切换次数,在一定程度上提高了微电网运行的可靠性。
[Abstract]:With the increasingly prominent energy and environmental problems, the development and full use of clean energy has become an important strategy for the sustainable development of the world and society. Microgrid can reduce the impact and adverse impact of distributed generation on the grid. One of the key technologies of microgrid is operation control. Flexible and changeable operation mode is the premise for microgrid to realize various economic and technological advantages. In this paper, the operation control strategy of microgrid is studied in two aspects. In the control strategy of micro-power supply, the micro-power supply is firstly divided into intermittent microsource and controllable micro-source according to the stability of power output. The DC side of the distributed microsource inverter is simplified, the control strategy of the inverter is studied, and the mathematical model of the three-phase voltage source inverter is established. Secondly, the current inner loop controller is designed. Three control methods of micro-power inverter, namely PQ control, droop control and V-f control, are analyzed in depth. It shows that changing the reference power of PQ control can realize the power flow control of common connection point in the operation mode of isolated island. The voltage and frequency of microgrid can be stabilized by the coordination of droop control and V-f control, and the sagging coefficient in droop control can be improved to change dynamically with the voltage and frequency of microgrid. Improved droop control can cause power gaps in the system, The voltage and frequency decrease of microgrid becomes smaller. Finally, the island operation mode is switched to the network operation mode by designing presynchronous control unit in droop control and V-f control. The master-slave control and peer-to-peer control are analyzed. It is known that peer-to-peer control is simple, reliable and easy to realize. But there is no guarantee of voltage and frequency stability. Master and slave control can support the voltage and frequency of the microgrid. However, it is necessary to change the control mode of the main control microsource when the operation mode is changing. Therefore, this paper proposes a comprehensive control method combining master and slave with peer-to-peer control, which can not only realize the stability of voltage and frequency. It can also reduce the frequency of switching of the control mode of the micro-power supply, and reduce the possibility of the failure of the switching mode of the control mode. To a certain extent, the reliability of microgrid operation is improved. Through the cooperation of micro-power control strategy and multi-power coordinated control strategy, the micro-grid can be operated in the network. The island operation and the stability of the voltage and frequency in the switching process between the two operation modes can effectively reduce the switching times of the main control microsource when the operation mode of the microgrid changes and to a certain extent improve the reliability of the microgrid operation.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM732

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