基于FPGA的三电平LCL有源滤波器控制策略研究

发布时间：2018-06-02 13:27

本文选题：三电平有源电力滤波器 + 改进型预测电流控制　；参考：《北方工业大学》2017年硕士论文

【摘要】：近年来非线性负载得到大量应用,导致大量谐波电流与无功电流注入到电网,对电网造成污染,而有源电力滤波器(Active Power Filter,APF)可有效解决谐波电流污染问题。三电平APF由于其特有的拓扑结构,具有耐压等级高、开关应力小等优点,在高压、大功率应用场合,研究价值和应用前景较大。本文以三相三线制二极管箝位型三电平有源电力滤波器为研究对象,对电流跟踪控制策略、LCL滤波器参数优化设计和有源阻尼控制策略等关键技术进行了深入分析。三电平APF工作原理和数学模型是其控制策略建立的基础。本文首先介绍了三电平APF的工作原理,在此基础上建立了三电平APF在abc坐标系下的数学模型,为了方便控制器的设计,继续推导了其在dq坐标系下的数学模型和交流小信号模型,为控制器设计奠定了基础。电流跟踪控制策略是决定三电平APF性能的关键因素。由于控制系统为数字控制系统,不可避免的为系统控制带来一拍延时。为此本文提出一种考虑输出补偿电流的改进型预测电流跟踪控制策略,在传统预测电流控制策略仅对指令电流进行预测的基础上,利用三电平APF离散数学模型,对输出补偿电流进行预测,可有效消除数字系统延时,显著提高三电平APF补偿效果和动态响应速度。LCL滤波器的参数对三电平APF补偿效果和高频滤波性能具有重要影响。为此,本文采用一种基于图解的方法进行LCL滤波器参数设计,建立了单相LCL滤波器的数学模型,说明了 LCL滤波器参数设计指标和步骤。LCL滤波器存在谐振问题。为解决这一固有问题,本文采用一种基于状态反馈极点配置的有源阻尼控制策略,通过配置系统闭环极点来抑制LCL滤波器的谐振尖峰。为了方便三电平APF调试,开发了一套电力电子变换器通用调试系统,可以实现三电平APF设备状态监测、数据显示、修改和系统控制。该系统包括上位机和下位机两部分,其中上位机负责设备状态监控、数据显示、修改与系统控制,下位机负责数据采集和存储;上、下位机通过Modbus通信协议完成数据传输。为验证本文所提控制策略,设计了三电平LCL有源电力滤波器实验平台,详细介绍了控制电路RC滤波参数设计过程。最后在实验平台完成了本文所提改进型预测电流跟踪控制策略和有源阻尼控制策略的硬件实验,验证了控制策略有效性。
[Abstract]:In recent years, a large number of nonlinear loads have been applied, resulting in a large amount of harmonic current and reactive current being injected into the power network, which causes pollution to the power network. The active Power filter (APF) can effectively solve the problem of harmonic current pollution. Due to its unique topology, three-level APF has the advantages of high voltage resistance and low switching stress, so it has great research value and application prospect in high-voltage and high-power applications. In this paper, three-phase three-wire diode-clamped three-level active power filter (APF) is used as the research object, and the key technologies such as the optimization design of LCL filter parameters and the active damping control strategy are deeply analyzed. The operating principle and mathematical model of three-level APF are the foundation of its control strategy. In this paper, the working principle of three-level APF is introduced, and the mathematical model of three-level APF in abc coordinate system is established on this basis, in order to facilitate the design of the controller, The mathematical model and AC small signal model in DQ coordinate system are derived, which lays a foundation for controller design. Current tracking control strategy is the key factor to determine the performance of three-level APF. Because the control system is a digital control system, it inevitably brings a beat delay for the system control. In this paper, an improved predictive current tracking control strategy considering the output compensation current is proposed. Based on the traditional predictive current control strategy which only predicts the instruction current, the three-level APF discrete mathematical model is used. By predicting the output compensation current, the delay of digital system can be effectively eliminated, and the parameters of three-level APF compensation and dynamic response speed. LCL filter have important influence on the three-level APF compensation effect and the performance of high-frequency filter. In this paper, a graphic method is used to design the parameters of LCL filter. The mathematical model of single-phase LCL filter is established, and the parameter design index of LCL filter and the resonance problem of step .LCL filter are explained. In order to solve this inherent problem, an active damping control strategy based on state feedback pole assignment is used to suppress the resonant spike of LCL filter by configuring the closed-loop poles of the system. In order to facilitate the debugging of three-level APF, a general debugging system of power electronic converter is developed, which can realize the state monitoring, data display, modification and system control of three-level APF equipment. The system consists of two parts: the upper computer and the lower computer, in which the upper computer is responsible for equipment state monitoring, data display, modification and system control, and the lower computer is responsible for data acquisition and storage, and the lower computer is responsible for data transmission through Modbus communication protocol. In order to verify the proposed control strategy, a three-level LCL active power filter experimental platform is designed, and the design process of RC filter parameters of the control circuit is introduced in detail. Finally, the hardware experiments of the improved predictive current tracking control strategy and the active damping control strategy proposed in this paper are completed on the experimental platform, and the effectiveness of the control strategy is verified.
【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】：TM761

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