同步逆变器的控制方法及闭环参数设计

发布时间：2018-05-23 14:19

本文选题：同步逆变器 + 并网逆变器　；参考：《华中科技大学》2015年硕士论文

【摘要】：基于可再生能源的分布式发电系统(Renewable Energy based Distributed Power Generation System,RE-DPGS)是开发和利用可再生能源的重要途径,对于缓解能源危机与环境污染具有重要意义。并网逆变器是RE-DPGS与电网的能量交换接口装置,同步逆变器(Synchronverter)是使并网逆变器模拟同步发电机特性,可以根据电网电压频率和幅值的变化自动调节其输出的有功功率和无功功率,为电网提供支撑。本文研究同步逆变器的控制策略及其闭环参数设计。本文首先详细推导了同步发电机的数学模型,接着从模拟同步发电机的角度给出了同步逆变器的控制方法,包括模拟同步发电机的惯性、频率有功功率下垂特性、电压幅值无功功率下垂特性。为了了解同步逆变器中的虚拟惯性作用,本文分析比较了虚拟惯性控制与下垂控制方法,得出虚拟惯性可以很好地提高系统频率和电压幅值稳定性。接着对同步逆变器功率环进行小信号建模,得出其工频小信号模型,并证明了其有功功率环和无功功率环的耦合很弱,因此其控制参数可分别独立设计。介绍了一种根据系统截止频率和相角裕度要求设计控制参数的方法,该方法在兼顾系统稳定性、动态性能和对功率脉动抑制能力要求的前提下,能够快速准确地计算出相应的控制参数。分析了开关管死区对同步逆变器输出电压和并网电流的影响,指出同一桥臂两只开关管的死区不同会导致并网电流中出现直流分量。为此,提出了一种基于虚拟电容的方法来抑制同步逆变器并网电流中的直流分量。为了验证本文理论分析的准确性,在实验室搭建了一台三相20kW同步逆变器原理样机。实验结果证明了同步逆变器控制策略的有效性和本文理论分析的正确性。
[Abstract]:Renewable Energy based Distributed Power Generation system RE-DPGSbased on renewable energy is an important way to develop and utilize renewable energy, which is of great significance to alleviate energy crisis and environmental pollution. Grid-connected inverter is an energy exchange interface between RE-DPGS and power grid. Synchronous inverter synchronizes the characteristics of synchronous generator. It can automatically adjust the active power and reactive power according to the change of voltage frequency and amplitude. Provide support for the power grid. This paper studies the control strategy of synchronous inverter and its closed-loop parameter design. In this paper, the mathematical model of synchronous generator is deduced in detail, and then the control method of synchronous inverter is given from the angle of simulating synchronous generator, including the inertia of analog synchronous generator and the droop characteristic of active power. Voltage amplitude / reactive power sag characteristics. In order to understand the virtual inertia effect in synchronous inverter, this paper analyzes and compares the virtual inertial control and droop control methods, and draws the conclusion that virtual inertia can improve the stability of the frequency and voltage amplitude of the system. Then the power loop of synchronous inverter is modeled with small signal and its power frequency model is obtained. It is proved that the coupling of active power loop and reactive power loop is very weak, so its control parameters can be designed independently. This paper introduces a method to design control parameters according to the system cut-off frequency and phase angle margin. The method takes into account the stability, dynamic performance and power pulsation suppression ability of the system. The control parameters can be calculated quickly and accurately. The effect of dead time of switch on output voltage and grid-connected current of synchronous inverter is analyzed. It is pointed out that different dead-time of two switches with the same bridge arm will result in DC component in grid-connected current. Therefore, a method based on virtual capacitance is proposed to suppress the DC component in the grid-connected current of synchronous inverter. In order to verify the accuracy of the theoretical analysis, a prototype of a three-phase 20kW synchronous inverter is built in the laboratory. The experimental results show that the control strategy of synchronous inverter is effective and the theoretical analysis is correct.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM464

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