18脉波不控整流外加辅助电路谐波抑制方法研究

发布时间：2018-01-25 23:33

本文关键词： 多脉波整流直流侧谐波抑制谐波畸变率电压不平衡度　出处：《中国矿业大学》2016年硕士论文　论文类型：学位论文

【摘要】：大功率整流电路会给电网带来大量的谐波污染,多脉波整流系统能很好的解决上述问题,但该系统并不能完全消除网侧低次谐波,为达到更好的谐波抑制效果,本文研究了一种应用于隔离场合的基于常规18脉波整流系统主电路拓扑结构的带单相逆变器的网侧谐波抑制系统。本文从常规12脉波整流系统出发,根据系统直流侧变量与交流侧变量之间的转换关系,计算出系统网侧电流和系统直流侧电压傅里叶表达式。基于直流侧谐波抑制原理,本文分别讨论了直流侧统一调制和直流侧电压可调这两种直流侧谐波抑制技术,并通过仿真分别验证了这两种方法对网侧电流谐波的抑制效果。本文在18脉波整流系统的基础上,研究了一种基于单相逆变器的直流侧谐波抑制系统。单相逆变器产生交流辅助方波电压,通过高频变压器耦合到系统直流侧,改进直流侧电流波形,使得网侧电流谐波得到抑制,并与常规18脉波整流系统输入电流及输出电压进行比较。多脉波整流系统输出电压不平衡的原因主要有网侧电压不平衡和整流变压器结构不对称。首先,本文研究了整流变压器绕组匝数不对称对系统输出电压不平衡的影响,根据三角形正余弦定理计算出它们之间的表达式,并通过仿真绘制出它们之间的波形示意图;其次,本文研究了变压器在结构对称的情况下,系统三相输入电压不平衡与整流变压器输出电压不平衡度之间的定量关系;最后研究了在各种不平衡条件下,网侧电流总谐波畸变率的变化规律,并与仿真结果进行比较。最后搭建了18脉波整流系统平台,给出了主电路器件选型的具体步骤及控制系统软件实现流程图。并对18脉波直流侧谐波抑制系统进行调试,完成实验验证。
[Abstract]:The high-power rectifier circuit will bring a lot of harmonic pollution to the power network, the multi-pulse rectifier system can solve the above problems well, but the system can not completely eliminate the low-order harmonics of the grid side, in order to achieve better harmonic suppression effect. A grid-side harmonic suppression system with single-phase inverter based on the main circuit topology of conventional 18-pulse rectifier system is studied in this paper. According to the conversion relationship between DC side variables and AC side variables, Fourier expressions of system network side current and system DC side voltage are calculated, based on the principle of DC side harmonic suppression. In this paper, two kinds of DC side harmonic suppression techniques are discussed, which are DC side unified modulation and DC side voltage adjustable. The simulation results show that these two methods can suppress the current harmonics on the grid side. This paper is based on the 18 pulse rectifier system. A DC side harmonic suppression system based on single-phase inverter is studied. The single-phase inverter generates AC auxiliary square wave voltage, which is coupled to the DC side of the system by high-frequency transformer to improve the DC side current waveform. The current harmonics on the grid side are suppressed. And compared with the conventional 18 pulse rectifier system input current and output voltage. The main reasons for the unbalanced output voltage of the multi-pulse rectifier system are the voltage imbalance of the grid side and the structure of the rectifier transformer asymmetry. First of all. In this paper, the influence of the unsymmetrical number of turns in the winding of rectifier transformer on the unbalanced output voltage of the system is studied, and the expressions between them are calculated according to the triangle sine cosine theorem. The waveform diagram between them is drawn by simulation. Secondly, the quantitative relationship between the unbalanced three-phase input voltage and the output voltage unbalance of rectifier transformer is studied in this paper. Finally, the variation law of total harmonic distortion rate of grid-side current under various unbalanced conditions is studied and compared with the simulation results. Finally, an 18-pulse rectifier system platform is built. The specific steps of the main circuit device selection and the software flow chart of the control system are given, and the 18 pulse DC side harmonic suppression system is debugged, and the experimental verification is completed.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TM761

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