微网分布式混合储能系统建模及控制策略研究

发布时间：2018-06-30 00:17

本文选题：微网 + 混合储能　；参考：《华中科技大学》2014年硕士论文

【摘要】：近年来随着环境污染、化石能源的耗尽、以及电力电子技术的发展，越来越多的新能源接入中低压电网，进而出现了供电新形式——微电网，它一般包含多种间歇性能源、负荷和相关的监控保护装置，有并网和孤网两种运行状态，主要采用主从控制和对等控制两种控制模式。微网为新能源并网打开了新的局面，但是也有诸多问题，例如可能给接入的电网造成功率扰动，孤网运行时电压和频率难以稳定，为了解决这些问题，储能装置必不可少。目前储能元件众多，各有优劣，其中液流电池（VRB）储存能量大，超级电容器（EDLC）充放电速度快，所以本文将两者结合，设计搭建了混合储能系统，针对其中DC/DC和DC/AC变换器的控制方法进行了研究，最终仿真分析了微网中分布式混合储能系统的作用。本文首先介绍了微网的基本结构和主从和对等两种控制模式，对两种控制模式的特点进行了对比，并阐述了储能对于微网安全稳定的必要性，在综合分析各种储能技术的基础上，提出了液流电池/超级电容器混合储能，进而开始对混合储能系统进行了结构设计和控制策略研究。然后，比较了储能系统并联和级联结构，，在此基础上改进得到带有两个DC/DC变换器的级联拓扑结构，并分别对液流电池和超级电容器进行等效建模。新颖的拓扑结构为结合储能元件的优势奠定基础，而DC/DC控制回路中将先进的BP神经网络算法与传统PID结合，真正实现了两者功率的合理分配——液流电池按照计划平稳充放电，超级电容器平抑快速波动。针对微网不同的运行方式，对DC/AC的控制也采取不同的控制目标和方法，其中P/V控制，意在维持并网模式下功率交换的恒定和电压的稳定，Droop控制可以实现并网和孤网模式之间的无缝转换，V/f控制则可以维持孤网模式下电压频率的无差控制。最后，仿真分析了混合储能对微网的三大作用，包括改善电能质量、提高供电可靠性和优化间歇性能源出力。此外，针对因Droop控制参数不合理引起的问题，提出了一种参数优化的方法，在等效简化微网结构之后，该方法以系统小信号状态空间方程为基础，综合考虑了系统渐近稳定、控制带宽和鲁棒性等因素，通过混沌粒子群算法寻优求出参数，最终仿真验证了该参数可以维持系统的电压和频率稳定，并实现功率的合理分配。
[Abstract]:In recent years, with the environmental pollution, the depletion of fossil energy, and the development of power electronics technology, more and more new energy sources are connected to the medium-low voltage power grid, and then a new form of power supply-microgrid has emerged, which generally contains a variety of intermittent energy. Load and related monitoring and protection devices have two operation states, connected and isolated, which are mainly controlled by master-slave control and peer-to-peer control. The microgrid opens up a new situation for the new energy grid, but there are many problems, such as the power disturbance of the connected power grid and the difficulty of voltage and frequency stability during the operation of the isolated grid. In order to solve these problems, the energy storage device is essential. At present, there are many energy storage components, each of which has its own advantages and disadvantages, among which the liquid flow battery (VRB) has a large energy storage capacity and a supercapacitor (EDLC) charge / discharge speed is high. So, a hybrid energy storage system is designed and built in this paper. The control methods of DC / DC and DC / AC converters are studied. Finally, the function of distributed hybrid energy storage system in microgrid is simulated and analyzed. This paper first introduces the basic structure of microgrid and the master-slave and peer-to-peer control modes, compares the characteristics of the two control modes, and expounds the necessity of energy storage for the security and stability of microgrid. Based on the comprehensive analysis of various energy storage technologies, the hybrid energy storage of liquid flow battery / supercapacitor is proposed, and the structure design and control strategy of the hybrid energy storage system are studied. Then, the parallel and cascade structures of the energy storage system are compared, and the cascade topology with two DC / DC converters is improved, and the equivalent modeling of the liquid-flow battery and the supercapacitor is carried out respectively. The novel topology lays the foundation for combining the advantages of energy storage elements, and the DC / DC control loop combines the advanced BP neural network algorithm with the traditional pid, and realizes the reasonable distribution of the power between them-the liquid flow battery charges and discharges smoothly according to the plan. Supercapacitors neutralize rapid fluctuations. According to the different operation mode of microgrid, the control of DC / AC also adopts different control objectives and methods, among which the P / V control, The purpose of this paper is to maintain constant power exchange and stable voltage in grid-connected mode. It can realize the seamless conversion between grid-connected and isolated grid-mode and can maintain the no-difference control of voltage frequency in isolated mode. Finally, three functions of hybrid energy storage on microgrid are simulated and analyzed, including improving power quality, improving reliability of power supply and optimizing intermittent energy output. In addition, in order to solve the problem caused by unreasonable Droop control parameters, a parameter optimization method is proposed. After equivalent simplification of microgrid structure, the method is based on the small signal state space equation of the system and considers the asymptotic stability of the system synthetically. Controlling bandwidth and robustness, the parameters are obtained by chaotic particle swarm optimization algorithm. The simulation results show that the parameters can maintain the voltage and frequency stability of the system and realize the reasonable power allocation.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM46

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