基于MMC的UPFC接地方式及本体保护策略研究

发布时间：2018-04-18 15:34

本文选题：MMC + UPFC　；参考：《华北电力大学(北京)》2017年硕士论文

【摘要】：基于模块化多电平换流器(modular multilevel converter,MMC)的统一潮流控制器(unified power flow controller,UPFC)是适应高电压大容量输电的高度可控型灵活交流输电系统装置,其构成复杂,故障影响不容忽视,对接地设计及保护策略要求高。本文以基于MMC的UPFC接地方式及本体保护策略为核心,围绕MMC-UPFC本体保护配置及配合、接地方式对故障特性及本体保护的影响、UPFC接入对系统保护的影响这三个部分开展研究。首先,本文介绍基于MMC的UPFC本体结构、工作原理及详细保护区域划分;结合上海MMC-UPFC示范工程进行仿真实验,考虑阀控制保护影响,重点分析了几种典型故障下的故障特性,指出传统保护可能存在的问题。并针对上述问题,改进了并联阀侧短引线差动保护,T接线差动保护及串联变压器差动保护。其次,针对接地方式对故障特性与本体保护的影响,提出三种可行的交流侧接地方式,分别为仅并联变阀侧中性点经大电阻接地,仅串联变阀侧中性点经大电阻接地及仅并联变阀侧中性点经小电阻接地。进一步,结合示范工程系统参数与RTDS实时数字仿真实验,详细分析不同接地方式对故障特性与保护配置的影响,重点讨论接地点位置对串联变网侧单相接地故障及对应保护配置影响,接地电阻阻值对阀侧短引线单相接地故障、换流器桥臂单相接地故障及相应保护配置影响,最终得出MMC-UPFC较优的接地方案。最后,针对UPFC接入对系统保护的影响,本文给出UPFC本体保护与系统保护的配合,根据示范工程实际需要,明确本体保护与系统保护的动作范围。进一步,将UPFC模型简化等效并仿真分析UPFC接入对故障特性的影响,搭建距离保护计算模型,比较UPFC不同接入地点、不同故障位置,距离保护不同原理情况下,线路首端保护安装处测量电阻、测量电抗及距离保护动作情况,分析UPFC接入对线路距离保护的影响。
[Abstract]:The unified power flow controller based on modular multilevel converter (Modular multilevel convertor) is a highly controllable flexible AC transmission system for high voltage and large capacity transmission. Its structure is complex and the fault influence can not be ignored.High requirements for grounding design and protection strategy.This paper focuses on the UPFC grounding mode and the protection strategy based on MMC. It focuses on the configuration and cooperation of the MMC-UPFC ontology protection, the influence of the grounding mode on the fault characteristics and the impact of the MMC-UPFC access on the system protection.First of all, this paper introduces the structure, working principle and detailed protection area division of UPFC based on MMC, and analyzes the fault characteristics of several typical faults based on the simulation experiment of Shanghai MMC-UPFC demonstration project, considering the influence of valve control protection.The possible problems of traditional protection are pointed out.Aiming at the above problems, this paper improves the parallel valve side short lead differential protection and the series transformer differential protection.Secondly, in view of the influence of grounding mode on fault characteristics and body protection, three feasible AC side grounding methods are put forward, namely, only the neutral point of the side of the parallel variable valve is grounded by large resistance.Only the neutral point on the side of the series variable valve is grounded by large resistance and only the neutral point of the side of the parallel variable valve is grounded with small resistance.Furthermore, the effects of different grounding modes on fault characteristics and protection configuration are analyzed in detail by combining the system parameters of the demonstration project and the real-time digital simulation experiment of RTDS.This paper mainly discusses the influence of grounding point position on single-phase grounding fault and corresponding protection configuration of series transformer grid, the influence of grounding resistance value on valve side short lead single-phase grounding fault, commutator bridge arm single-phase grounding fault and corresponding protection configuration.Finally, the optimal grounding scheme of MMC-UPFC is obtained.Finally, aiming at the influence of UPFC access on system protection, this paper presents the cooperation of UPFC ontology protection and system protection. According to the actual needs of demonstration project, the scope of action between ontology protection and system protection is defined.Furthermore, the UPFC model is simplified and equivalent, and the influence of UPFC access on fault characteristics is simulated and analyzed. A distance protection calculation model is built to compare the different access locations, different fault locations and different principles of distance protection in UPFC.The resistance, reactance and distance protection action are measured at the first end of the line protection installation, and the influence of UPFC access on the line distance protection is analyzed.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM761;TM77

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