基于MMC-HVDC的控制策略仿真分析与故障测距研究

发布时间：2018-05-22 19:02

本文选题：MMC + 柔性直流输电　；参考：《昆明理工大学》2017年硕士论文

【摘要】：模块化多电平换流器(Modular Multilevel Converter,MMC)由于具有波形质量好,不需要再配置滤波器装置,开关损耗低,器件均压简单,采用了模块化设计,容易拓展,可以独立的控制有功功率和无功功率,可以向无源系统供电等优点而得到越来越多的关注与应用,但对于模块化多电平换流器的柔性直流输电(MMC-HVDC)的研究还只是处于初始阶段。本文主要针对MMC-HVDC系统的控制策略和直流侧单极接地故障测距进行分析与研究,本文的结构如下:首先分析了 MMC的拓扑结构及工作原理,分析了子模块不同的工作状态,分析了三相模块化多电平换流器的工作原理及模块化多电平换流器中子模块的类型。其次,介绍了 MMC-HVDC系统的构成及其主电路的拓扑结构,由主电路拓扑结构图得到该系统的等效电路图。分析了 MMC的暂态数学模型及MMC-HVDC控制系统的组成和结构,研究了各层控制系统的功能与控制器的结构。在PSCDA/EMTDC仿真软件中搭建了两端MMC-HVDC系统的仿真模型,对系统在稳态运行时、有功功率发生阶跃时、直流电压发生阶跃时其他物理量的响应特性进行了仿真分析。再次,分析了电容电压产生波动及产生环流的原因,介绍了 MMC电容电压的均衡控制及环流抑制控制器的原理,分析了通用环流抑制器,利用仿真模型验证了该控制器能够改善桥臂电流畸变的情况。最后,研究了 MMC-HVDC系统的边界条件及行波的传变特性,仿真分析了不同的过渡电阻及不同的故障距离对行波特性的影响。利用行波测距方法对系统的直流侧发生单极接地故障的情况进行了故障测距的研究。
[Abstract]:Because of its good waveform quality, no need to reconfigure filter devices, low switching loss, simple voltage sharing, modularized design and easy expansion, modularized multilevel converter (MMC) is easy to be extended, because of its good waveform quality, low switching loss and simple voltage sharing. More and more attention has been paid to the advantages of controlling active and reactive power independently and supplying power to passive systems. However, the study of modularized multilevel converters for flexible direct current transmission (HVDC) is still in its initial stage. In this paper, the control strategy of MMC-HVDC system and DC side single-pole fault location are analyzed and studied. The structure of this paper is as follows: firstly, the topological structure and working principle of MMC are analyzed, and the different working states of sub-modules are analyzed. The working principle of three-phase modularized multilevel converter and the type of neutron module of modularized multilevel converter are analyzed. Secondly, the structure of the MMC-HVDC system and the topology of the main circuit are introduced. The equivalent circuit diagram of the system is obtained from the topology structure diagram of the main circuit. The transient mathematical model of MMC and the composition and structure of MMC-HVDC control system are analyzed. The functions of each layer control system and the structure of controller are studied. The simulation model of two ends of MMC-HVDC system is built in the PSCDA/EMTDC simulation software. The response characteristics of other physical quantities are simulated and analyzed when the active power step occurs and the DC voltage step occurs when the system is in steady state. Thirdly, the causes of the fluctuation of capacitor voltage and the circulation are analyzed, the equalization control of MMC capacitor voltage and the principle of the loop suppression controller are introduced, and the general circulation suppressor is analyzed. The simulation model is used to verify that the controller can improve the current distortion of the bridge arm. Finally, the boundary conditions of MMC-HVDC system and the transmission characteristics of traveling wave are studied, and the effects of different transition resistance and different fault distance on the traveling wave characteristics are simulated and analyzed. The traveling wave fault location method is used to study the fault location of DC side of the system.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM721.1;TM46

【参考文献】