引入虚拟阻抗的逆变器并联均流的控制方法

发布时间：2018-05-05 00:04

本文选题：SPWM逆变器 + 负序分量　；参考：《华中科技大学》2015年硕士论文

【摘要】：本文致力于利用SPWM以及其他的调制方法来控制UPS的单机以及并机的运行。首先介绍了UPS的特点及要求的性能指标,本文对逆变器的电路控制策略、非线性负载及不平衡负载、并联模块的环流性质及有功功率,无功功率的均分等问题进行了详细的探讨。本文首先推导了逆变器开环运行时在abc以及dq坐标系下的数学模型以及传递函数,并指出了它的稳态和动态特性的不足之处,从而引出了逆变器的双闭环控制。另外对于三相半桥逆变器需要考虑不平衡负载,本文介绍了一种dq坐标系下正负序分量分离的方法,以及??坐标系下的PR控制法。在单机运行良好的基础上,本文深入研究了逆变器在相并联的过程中输出功率的传输特性,建立了逆变器并联模块的近似数学模型。逆变器并联时的环流与2个因素相关:(1)2台逆变器的等效电压源之差(包括幅值和相位),这与给定电压有关;(2)2台逆变器在一定的控制方法下的对外输出阻抗之差(包括阻值和感值)。我们一般利用逆变器的输出有功差和无功差来调节给定电压的幅值以及相位(频率)。但由于逆变器的输出阻抗并不一定是纯感性的,而通常是既有阻性分量也有感性分量,所以并联系统中均流控制的有功差和无功差与给定电压的幅值差及相位差之间存在耦合关系,故一般的下垂控制法不仅耦合严重,而且准确度较差,本文先对这种方法进行分析,然后引入了虚拟阻抗的概念,可实现均流算法中的解耦,而且还可以大大减弱由于输出阻抗的差别而带来的环流。
[Abstract]:In this paper, SPWM and other modulation methods are used to control the single and parallel operation of UPS. Firstly, the characteristics and performance index of UPS are introduced. The circuit control strategy of inverter, nonlinear load and unbalanced load, circulation property of parallel module and active power are introduced in this paper. The average distribution of reactive power is discussed in detail. In this paper, the mathematical model and transfer function of the inverter in abc and DQ coordinate system are derived firstly, and the shortcomings of its steady and dynamic characteristics are pointed out, which leads to the double closed loop control of the inverter. In addition, for the three-phase half-bridge inverter to consider the unbalanced load, this paper introduces a method of separating the positive and negative sequence components in dq coordinate system, and also introduces the method of separation of the positive and negative sequence components in the dq coordinate system. PR control method in coordinate system. Based on the good operation of the single machine, the transmission characteristics of the output power of the inverter in the process of parallel operation are studied in depth, and the approximate mathematical model of the parallel module of the inverter is established. The circulating current of the inverter in parallel is related to two factors: the difference of the equivalent voltage source (including amplitude and phase) of the two inverters, which is related to the external output impedance of the two inverters with a given voltage under a certain control method It includes resistance value and sense value. We generally use the output active power difference and reactive power difference of the inverter to adjust the amplitude and phase of a given voltage. However, the output impedance of the inverter is not necessarily pure inductive, but usually has both resistive and inductive components. So there is a coupling relationship between active power difference and reactive power difference of current sharing control in parallel system and amplitude difference and phase difference of given voltage, so the general droop control method not only has serious coupling, but also has poor accuracy. This paper first analyzes this method, then introduces the concept of virtual impedance, which can decouple the current sharing algorithm and greatly reduce the circulation caused by the difference of output impedance.
【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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