基于分层控制的并联逆变器功率均衡技术研究

发布时间：2018-06-23 09:23

本文选题：微电网 + 下垂控制　；参考：《北方工业大学》2017年硕士论文

【摘要】：使用化石燃料发电的传统发电方式带来环境问题日益凸显,因此将可再生能源集成到当前的电力系统中是今后发展的趋势。微电网的提出极大促进了新能源在配电网中的集成,有利于增强电压支撑能力,提高系统的效率和可靠性。在当前微电网控制中,下垂控制是实现有功和无功功率分配的基本方法,但该方法并不适用于阻性线路为主的中低压配电网。因此,本文围绕适用于微电网系统中低压特点的负荷分配控制策略展开研究,主要工作包括:(1)整体介绍当前微电网接口逆变器控制技术,分别从单元级和系统级详细分析现有的技术原理和优缺点。分析了当前并联逆变器控制策略研究现状,介绍当前的研究重点和方向。(2)在旋转坐标系下建立三相逆变器数学模型,进而推得电压电流双环控制器模型,并通过频域法分析微源逆变器闭环控制特性,设计了滤波器参数和控制器参数。通过微源功率传输特性建立微源下垂控制器,给出了下垂系数设计依据。同时在逆变器并联模型的基础上,分析了并联逆变器环流的成因和本质,为后续工作奠定理论基础。(3)阐述了基于下垂控制的传统分层控制基本原理和局限性,引入虚拟阻抗的基本概念,并提出一种自适应虚拟阻抗分层控制策略:在传统一级控制基础上,引入功率等效阻抗概念,从而有效解决了本地负荷对多逆变器功率分配的影响。并在传统二级控制调压调频的基础上,引入了调功的控制策略。介绍了传输线路参数辨识的意义,并通过带遗忘因子的递推最小二乘方法对线路阻抗参数进行辨识,从而实现了不完全依赖通信的分布式控制策略。仿真证实改进的分层控制策略可有效解决本地负荷不匹配带来的功率分配误差。(4)搭建功率均衡半实物仿真平台,详细介绍了基于模型的设计方法,通过硬件在环方式对所提控制策略进行了实验验证。
[Abstract]:The traditional power generation method using fossil fuels has brought more and more environmental problems, so it is a trend to integrate renewable energy into the current power system. The proposed microgrid greatly promotes the integration of new energy in the distribution network, which is conducive to enhancing the voltage support capacity and improving the efficiency and reliability of the system. Sagging control is the basic method to realize active and reactive power distribution in microgrid control, but it is not suitable for middle and low voltage distribution networks with resistive lines. Therefore, this paper focuses on the load distribution control strategy suitable for the characteristics of low voltage in microgrid system. The main work includes: (1) introduce the current control technology of microgrid interface inverter. The existing technical principles, advantages and disadvantages are analyzed in detail from unit level and system level respectively. The current research status of the control strategy of parallel inverter is analyzed, and the emphasis and direction of the current research are introduced. (2) the mathematical model of three-phase inverter is established in the rotating coordinate system, and the voltage and current dual-loop controller model is derived. The closed-loop control characteristics of micro-source inverter are analyzed by frequency domain method, and filter parameters and controller parameters are designed. The microsource droop controller is established by the power transmission characteristics of microsource, and the design basis of droop coefficient is given. At the same time, on the basis of the parallel model of the inverter, the cause and essence of the circulating current of the parallel inverter are analyzed, which lays a theoretical foundation for the subsequent work. (3) the basic principle and limitation of the traditional hierarchical control based on droop control are expounded. The basic concept of virtual impedance is introduced, and an adaptive hierarchical control strategy of virtual impedance is proposed: based on the traditional primary control, the concept of power equivalent impedance is introduced, which effectively solves the influence of local load on power distribution of multi-inverter. On the basis of traditional two-stage control and frequency modulation, the control strategy of power regulation is introduced. The significance of transmission line parameter identification is introduced, and the recursive least square method with forgetting factor is used to identify the line impedance parameters, thus realizing the distributed control strategy which is not completely dependent on communication. Simulation results show that the improved hierarchical control strategy can effectively solve the power allocation error caused by local load mismatch. (4) the simulation platform of power balance is built and the model-based design method is introduced in detail. The proposed control strategy is verified by hardware in loop mode.
【学位授予单位】：北方工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM464

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