孤岛微网分布式功率控制方法研究

发布时间：2018-07-08 08:47

本文选题：微网 + 分布式控制　；参考：《东北电力大学》2017年硕士论文

【摘要】：微网孤岛运行中,下垂控制作为一种广泛使用的方法,能够实现负荷功率在各分布式电源间的按比例分配,但由于低压微网一般呈阻性,且受到分布式电源输出阻抗以及线路阻抗不匹配的影响,负荷无功功率很难实现按比例分配,另外下垂控制作为一种有差控制,负荷变化后,电压、频率会有误差。为解决上述两种问题,本文对其进行了相关研究。本文首先研究了孤岛微网的分布式一级功率控制,给出了微网中无逆变器接口分布式电源以及逆变器接口分布式电源的控制方法,确定下垂控制能够按比例分配负荷功率的变化,探讨了分布式二级控制的理论基础,引进了通信有向图、一阶一致性控制以及含有领导者节点的一致性控制,在分布式一级及二级控制的基础之上,构建了一种以下垂控制作为一级控制的分布式分级控制结构,该结构一级控制主要用来分配负荷功率,二级控制则主要用于弥补一级控制带来的电压、频率偏差。然后,针对传统下垂控制方法不能按比例分配负荷无功功率的问题,本文提出了一种基于坐标变换的改进下垂控制方法,并设计了改进下垂控制器,分析了孤岛微网的功率分配机理,根据不同的线路参数特征设计了三种场景的仿真算例并进行了验证。最后,为了解决改进下垂控制方法带来的电压、频率偏差问题,本文提出了一种分布式二级控制方法和一种改进分布式二级控制方法,并分别按照两种方法设计了虚拟无功-电压控制器和虚拟有功-频率控制器,为验证两种方法的有效性,分别搭建了一个简单网络和一个网状网络的仿真算例进行了仿真验证。通过仿真验证得知,本文提出的分布式一级改进下垂控制方法不仅能够在低压微网阻性网络中实现负荷无功功率的按比例分配,也能适用于阻感性的中压微网网络;本文提出的分布式二级控制方法以及对其进行的改进控制方法相比于改进下垂控制方法以及集中式二级控制方法,能更好改善电压及频率质量。
[Abstract]:In the operation of microgrid islanding, sagging control, as a widely used method, can realize the proportional distribution of load power among the distributed power sources, but the low voltage microgrid is generally resistive. Due to the mismatch of output impedance and line impedance of distributed power supply, it is difficult to realize proportional distribution of load reactive power. In addition, sagging control is a kind of differential control. After load changes, there will be errors in voltage and frequency. In order to solve the above two kinds of problems, this paper has carried on the related research to them. In this paper, the distributed primary power control of island microgrid is studied, and the control methods of distributed power supply without inverter interface and inverter interface in microgrid are given. It is determined that droop control can distribute load power according to proportion. The theoretical basis of distributed secondary control is discussed. Communication digraph, first-order consistency control and consistency control with leader nodes are introduced. On the basis of distributed primary and secondary control, a kind of distributed hierarchical control structure with droop control as primary control is constructed, which is mainly used to distribute load power. The second-level control is mainly used to compensate the voltage and frequency deviation brought by the first-level control. Then, aiming at the problem that the traditional droop control method can not distribute the reactive power according to the proportion of load, an improved droop control method based on coordinate transformation is proposed in this paper, and an improved droop controller is designed. The power distribution mechanism of island microgrid is analyzed, and simulation examples of three scenarios are designed and verified according to different line parameters. Finally, in order to solve the voltage and frequency deviation problem caused by the improved droop control method, a distributed secondary control method and an improved distributed secondary control method are proposed in this paper. The virtual reactive power voltage controller and the virtual active power frequency controller are designed according to the two methods respectively. In order to verify the effectiveness of the two methods, a simple network and a mesh network simulation examples are built to verify the effectiveness of the two methods. The simulation results show that the improved droop control method proposed in this paper can not only realize the proportional distribution of load reactive power in low-voltage microgrid resistive networks, but also be suitable for medium-voltage microgrid networks with resistive inductance. Compared with the improved droop control method and the centralized two-stage control method, the distributed two-stage control method and the improved control method proposed in this paper can improve the voltage and frequency quality better than the improved sagging control method and the centralized two-stage control method.
【学位授予单位】：东北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM727

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