三相不平衡问题的分析与研究.doc

PAGE 4 论文题目：配电网三相不平衡问题的分析与研究 专 业：电气工程及其自动化 本 科 生：xx （签名） 指导教师：xx （签名） 摘 要 三相不平衡因素分为事故性和正常性两大类。本文针对正常性三相不平衡进行研究，阐明了三相不平衡对供电系统中变压器、电动机、发电机，输电线路等的危害,以及配电网三相平衡的重要性。本文通过MATLAB仿真对三相不平衡产生原因进行了建模和分析：1、单相接地是配电系统最常见故障，多发生潮湿、多雨天气。一般由于导线断线落地、绝缘子击穿等原因造成，最终引发电压和电流的不平衡。2、电压互感器铁磁谐振，主要原因是系统中电磁式电压互感器由于各种原因导致铁心磁饱和，从而与系统电容产生铁磁谐振，引起三相不平衡。3、消弧线圈，中性点经消弧线圈接地能使三相不平衡度增大，并当与系统电容发生谐振时，三相电压都骤增，对系统设备损坏很大。针对三相不平衡的不同起因，进行 MATLAB仿真，得到了三相电压波形图及电压值，并根据仿真结果进行详细分析，提出相应的解决措施。 本课题是以35kV配电网三相不平衡项目为依托，通过建模仿真分析与研究，找出了该电网三相电压不平衡的起因，并提出了解决电压不平衡的方案及措施。本文的研究方法和结果既有针对性地解决了实际中的问题同时也提供了一种行之有效的理论分析方法，可以有效地提高电力系统的运行和管理水平。 关键词:三相不平衡，消弧线圈，MATLAB仿真，铁磁谐振 Subject : Unbalanced three-phase distribution network analysis and research Specialty : Power System and Automation Name : xx (Signature) Instructor: xx (Signature) ABSTRACT Unbalanced three-phase factors are divided into two major categories of accidents and normal.For normal sexual unbalanced three-phase study, illustrates the hazards of unbalanced three-phase power supply systems, transformers, motors, generators, transmission lines, and with the importance of the grid three-phase equilibrium. MATLAB simulation of three-phase imbalance causes the modeling and analysis: 1 .Single-phase grounding is the most common failure distribution system, occurs damp, wet weather. General because the wires break ground, insulator breakdown causes such as, eventually cause the voltage and current imbalance. 2. ferromagnetic resonance of saturated voltage transformer. Direct-to-ground inductive reactance of system isunbalanced partly in general system. Because voltage transformer is saturated,direct-to-ground inductive reactance is unbalanced partly. 3. effect of extinction coil. Thedegree of three-phase unbalance is increased by adding extinction coil. Th