逆变器的三相不平衡负载控制方法研究

发布时间：2018-01-06 05:40

本文关键词：逆变器的三相不平衡负载控制方法研究　出处：《西南交通大学》2014年硕士论文　论文类型：学位论文

【摘要】：三相电压是否对称是判断电能质量好坏的一个重要参数,这对用电设备能否安全稳定工作有很大的影响。由于分布式发电(如风力发电或光伏发电)会出现离网带不对称负载工作状态以及UPS或者航空电源等也会有出现不平衡负载情况,因此本文针对三相逆变器的输出电压不平衡问题展开研究工作。本文首先将普通三相逆变器作为研究对象,分析传统三相逆变器在负载平衡条件下能够很好输出三相对称电压,但对于负载不平衡或非线性负载而言,三相输出电压不能满足国标中的用电要求。对三种瞬时对称分量法进行了详细的分析与推导,在Matlab/Simulink仿真环境下建立三种瞬时对称分量法仿真模型,分析各自的优缺点。在对传统三相逆变器不平衡问题产生机理进行了分析的基础上,采用线性叠加原理和对称分量法对带△/Y隔离变压器三相逆变器研究,分别得到各相序的T型等值电路,列出微分方程进行计算。分析带△/Y隔离变压器的三相逆变器带不平衡负载的能力并搭建模型仿真论证。其次,针对三相逆变器带不平衡负载的能力由逆变器拓扑和控制策略共同决定,本文深入研究了三相四桥臂拓扑抗不平衡负载的能力。在三相静止abc坐标系下建立了数学模型并进行了稳态分析。针对三相四桥臂的拓扑特点,摒弃了基于αβγ坐标系下的三维SVPWM调制算法,采用了简便明了的基于abc坐标系的三维SVPWM,给出了详细的计算分析过程。简单介绍了TI公司设计的TMS320F28335DSP控制芯片的功能,进行初始化程序设计并列出初始化流程图。根据三维SVPWM算法思想画出流程图,利用C语言写出程序,在DSP上对3DSVPWM调制算法实现。由于采用的PI调节器无法对时变的交流量实现无静差跟踪控制,因此基于正负序各自特点建立了双同步旋转坐标系,有效的去除了正负序转换到直流量时2倍频分量的影响。为了消除零序分量对系统的影响,考虑到零序分量在旋转坐标系下值为零,因此在传统的PI直接控制法基础上,提出了加入PR比例谐振控制改进型以及利用零序虚拟构造αβ坐标系改进型等两种独立控制法进行了详细的讨论分析,并利用Matlab/Simulink对这三种方法进行仿真,比较各自优劣点,降低了工作复杂难度且对零序抑制效果明显。最后对系统进行参数设计,将结合了双闭环控制的三相四桥臂拓扑在各种带载情况下利用Matlab/Simulink建立仿真模型,与三相三桥臂及带隔离变压器的拓扑仿真结果做了对比分析,突出了三相四桥臂带不平衡负载的能力,验证了控制策略的正确性。
[Abstract]:Whether the three-phase voltage is symmetrical or not is an important parameter to judge the power quality. This will have a great impact on the safety and stability of electrical equipment. Because of distributed generation (such as wind power or photovoltaic power generation). There will be an off-grid asymmetric load working state, as well as UPS or aeronautical power will also have an unbalanced load situation. Therefore, this paper focuses on the unbalanced output voltage of three-phase inverter. In this paper, the common three-phase inverter is first taken as the research object, and it is analyzed that the traditional three-phase inverter can output the three-phase symmetrical voltage well under the condition of load balance, but for the unbalanced load or nonlinear load. The three-phase output voltage can not meet the requirements of the national standard. The three kinds of instantaneous symmetric component method are analyzed and deduced in detail. Three kinds of instantaneous symmetric component simulation models are established in Matlab/Simulink simulation environment. Based on the analysis of the generation mechanism of unbalanced problem of traditional three-phase inverter, the linear superposition principle and the symmetrical component method are used to study the three-phase inverter with a / Y isolation transformer. The T-type equivalent circuits of each phase sequence are obtained, the differential equations are listed for calculation, and the ability of three-phase inverter with Y / Y isolation transformer with unbalanced load is analyzed and the model simulation is built. Secondly, the ability of three-phase inverter with unbalanced load is determined by inverter topology and control strategy. In this paper, the topological anti-unbalanced load capability of three-phase four-arm is deeply studied. The mathematical model is established in three-phase static abc coordinate system and the steady-state analysis is carried out. The topological characteristics of three-phase four-leg are analyzed. The 3D SVPWM modulation algorithm based on 伪尾纬 coordinate system is abandoned, and a simple and clear 3D SVPWM based on abc coordinate system is adopted. The detailed calculation and analysis process is given, and the functions of the TMS320F28335DSP control chip designed by TI Company are introduced briefly. Carry on initialization program design and list initialization flowchart. According to the idea of three-dimensional SVPWM algorithm draw the flow chart, use C language to write the program. The 3DSVPWM modulation algorithm is realized on DSP. Because the Pi regulator can not realize the static error tracking control for the time-varying AC quantity. Therefore, based on the characteristics of positive and negative sequence, a double synchronous rotating coordinate system is established, which effectively removes the influence of the frequency doubling component when the positive and negative sequence is converted to DC. In order to eliminate the influence of the zero-sequence component on the system, considering that the zero-sequence component is zero in the rotating coordinate system, it is based on the traditional Pi direct control method. Two independent control methods including PR proportional resonance control and 伪尾 coordinate system improvement are proposed and discussed in detail. The three methods are simulated by Matlab/Simulink, and the advantages and disadvantages of each method are compared. The complexity of the work is reduced and the effect of zero sequence suppression is obvious. Finally, the parameters of the system are designed. The three-phase four-arm topology with double closed-loop control is used to establish the simulation model with Matlab/Simulink under various load conditions. Compared with the topology simulation results of three-phase three-leg and isolating transformer, the ability of three-phase four-arm with unbalanced load is highlighted, and the correctness of the control strategy is verified.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM464

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