直流微电网稳定控制策略研究

发布时间：2018-03-23 20:14

本文选题：直流微电网　切入点：主从控制　出处：《南京理工大学》2017年硕士论文

【摘要】：在能源需求和环境问题的双重压力下,为了充分发挥分布式发电的优势,减小分布式电源接入大电网时对大电网产生的供电可靠性及电能质量方面的负面影响,微电网的概念由此提出。而伴随着直流负荷越来越普遍的情况,损耗较小、可控性强的直流微电网具有很强的发展潜力,对其的研究也越来越多。直流微电网分为孤岛和并网两种运行模式,实现两种模式下的稳定运行及平滑切换是必要的,因此研究直流微电网稳定控制策略是十分重要的。直流微电网的稳定控制主要分为两块内容,一是直流微电网能量协调管理策略,二是直流母线电压稳定控制策略。本文首先介绍了直流微电网的概念,归纳了直流微电网的发展现状和稳定控制研究现状。然后选取典型微电源,建立了光伏电池的数学实用模型,在得到光伏电池输出特性曲线的基础上采用了扰动观察法实现了光伏电池的最大功率跟踪;建立了蓄电池的通用数学模型,在Buck-Boost电路小信号分析的基础上实现了蓄电池的充放电控制;对双向DC/AC数学模型进行派克变换,实现了双向DC/AC变流器恒直流母线电压的解耦控制。其次,以直流微电网能量管理策略为研究对象,详细分析了直流微电网主从控制策略,对蓄电池作为正常运行时主电源情况下的并网模式和孤岛模式下的能量协调管理进行了分析,并对蓄电池退出运行时系统的能量管理进行了研究。以各变流器输出未达到限流值为前提,对直流微电网并网正常运行、孤岛运行、并网与孤岛切换以及蓄电池退出时并网运行四种运行方式进行了仿真分析,验证了主从控制策略的可行性。针对传统PI控制无法满足系统大扰动下直流母线电压的稳定性,对双向Buck-Boost变流器提出了基于状态反馈线性化的逆推滑模控制,通过仿真证明其响应速度快、扩大了系统的稳定区域的优点;对双向DC/AC变流器提出了自适应逆推滑模控制,该方法能很好地跟踪系统不确定参数,具有响应速度快、最大偏差量小的特点,系统的鲁棒性得到了提升。
[Abstract]:Under the dual pressure of energy demand and environmental problems, in order to give full play to the advantages of distributed generation and reduce the negative impact on power supply reliability and power quality when distributed generation is connected to large power grid, The concept of microgrid is put forward. With the increasing prevalence of DC load, the DC microgrid with low loss and strong controllability has great potential for development. The DC microgrid is divided into two operation modes: isolated island and grid-connected, so it is necessary to realize stable operation and smooth switching between the two modes. Therefore, it is very important to study the stability control strategy of DC microgrid. The stability control of DC microgrid is mainly divided into two parts: one is the coordinated energy management strategy of DC microgrid. The second is the voltage stability control strategy of DC bus. Firstly, this paper introduces the concept of DC microgrid, summarizes the development status and stability control status of DC microgrid, and then selects the typical micro-power supply. A practical mathematical model of photovoltaic cell is established. Based on the output characteristic curve of photovoltaic cell, the maximum power tracking of photovoltaic cell is realized by perturbation observation method, and the general mathematical model of battery is established. On the basis of small signal analysis of Buck-Boost circuit, the charge and discharge control of battery is realized, and the decoupling control of constant DC bus voltage of bidirectional DC/AC converter is realized by using Pike transform to the mathematical model of bidirectional DC/AC. Taking the energy management strategy of DC microgrid as the research object, the master-slave control strategy of DC microgrid is analyzed in detail, and the coordinated energy management in grid-connected mode and islanding mode is analyzed. Based on the premise that the output of each converter does not reach the current limit value, the DC microgrid is connected to the grid normally, and the isolated island is operated, and the energy management of the system is studied when the battery is out of operation. The simulation analysis of four operation modes of grid-connected and islanded switching and grid-connected operation when battery exits is carried out, which verifies the feasibility of master-slave control strategy. The traditional Pi control can not meet the stability of DC busbar voltage under the large disturbance of the system. A sliding mode control based on state feedback linearization is proposed for the bidirectional Buck-Boost converter. The simulation results show that its response speed is fast and the stable region of the system is enlarged, and the adaptive backstepping sliding mode control is proposed for the bidirectional DC/AC converter. This method can track the uncertain parameters of the system well and has the characteristics of fast response speed and small maximum deviation. The robustness of the system is improved.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM727

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