孤岛微网逆变器控制与并联技术研究

发布时间：2018-03-10 02:09

本文选题：三相全桥逆变器　切入点：比例准谐振控制　出处：《哈尔滨工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着电力电子技术的发展,由多台逆变器配合其他发电设备共同构成的低压交流微网常作为主电网的后备或替代而得到广泛应用。交流微网中供电设备不连接主电网而独立工作的模式即孤岛微网模式。孤岛微网中的不平衡非线性负载会造成电压畸变供电质量降低,因此对逆变器的电压控制技术提出了较高的要求。由于失去主电网作为电压支撑,孤岛模式微网中的逆变器需要与其他逆变器或发电设备共同工作在电压源模式提供负载电压,因此需研究逆变器的电压源并联运行技术。本文针对三相孤岛微网,分析了微网常用的三相逆变器的拓扑结构与优缺点,选择基于单相独立控制的三相全桥逆变器作为功率变换器,该拓扑具有母线电压利用率高的优点并能够有效应对负载不平衡造成的输出电压不对称。针对三相全桥逆变器的单机控制策略,本文分析了大功率下传统电压电流双闭环控制中电流内环存在的缺陷,并改用电压单闭环控制,通过对比单闭环和双闭环的性能提出了控制器的相位补偿和增强稳定性的要求。在此基础上,提出一种基于比例准谐振-重复控制并联结构的复合控制策略。其中比例准谐振控制通过增加相位超前补偿提高基波控制性能,重复控制设计了基于模型对消滤波器的控制策略提高稳定性并抑制电压谐波。针对电压单闭环控制缺乏电流环限流的问题,本文提出一种基于电压电流幅值检测的控制器切换策略,实现过流情况下的电流环限流控制。通过分析无源阻尼对系统模型的影响,采用电容回路无源阻尼增强两种控制模式下的稳定性。对于三相逆变器的并联组网,本文研究基于无互联线的功率下垂控制。通过建立数学模型分析均功率调节过程动态特性,提出下垂控制的改进策略增加系统稳定性。最后,设计以ARM控制芯片STM32F407为核心的三相全桥逆变器实验硬件平台并对系统软件进行编程实验。在实验平台上验证了所提出控制策有较强的带不平衡非线性负载的能力且能够通过两种控制模式的切换进行限流保护。
[Abstract]:With the development of power electronics technology, Low-voltage AC microgrid, which is composed of several inverters and other generation equipments, is widely used as the backup or substitute of the main grid. The mode in which the power supply equipment in AC microgrid works independently without connecting to the main grid is isolated. Island microgrid mode. The unbalanced nonlinear load in the island microgrid will cause the voltage distortion to reduce the quality of power supply. Therefore, the voltage control technology of the inverter is required. Because of the loss of the main grid as the voltage support, the inverter in the island-mode microgrid needs to work with other inverters or generating equipment to provide the load voltage in the voltage source mode. Therefore, it is necessary to study the voltage source parallel operation technology of the inverter. In this paper, the topology structure, advantages and disadvantages of the three-phase inverter commonly used in micro-grid are analyzed, aiming at the three-phase isolated microgrid. Three-phase full-bridge inverter based on single-phase independent control is selected as power converter. The topology has the advantage of high bus voltage utilization and can effectively deal with the asymmetry of output voltage caused by unbalanced load. The single-machine control strategy for three-phase full-bridge inverter is proposed. In this paper, the defects of the current inner loop in the traditional voltage and current double closed loop control under high power are analyzed, and the voltage single closed loop control is used. By comparing the performance of single closed loop and double closed loop, the requirements of phase compensation and enhanced stability of the controller are put forward. A compound control strategy based on proportional quasi-resonance and repetitive control parallel structure is proposed, in which proportional quasi-resonance control improves fundamental wave control performance by increasing phase advance compensation. The control strategy based on model canceling filter is designed to improve stability and suppress voltage harmonics. In this paper, a controller switching strategy based on voltage and current amplitude detection is proposed to realize current loop current limiting control under overcurrent. The influence of passive damping on the system model is analyzed. The passive damping of capacitor loop is used to enhance the stability of the two control modes. For the three-phase inverter connected in parallel, this paper studies the power droop control based on the non-interconnected wire. The dynamic characteristics of the process of average power regulation are analyzed by establishing a mathematical model. An improved strategy of droop control is proposed to increase the stability of the system. Finally, The experimental hardware platform of three-phase full-bridge inverter with ARM control chip STM32F407 as the core is designed and the system software is programmed. The ability of the proposed control strategy with unbalanced nonlinear load is verified on the experimental platform. And the current limiting protection can be carried out by switching between two control modes.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM464

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