文档介绍：毕业设计(论文)
变压器励磁涌流抑制控制器设计
系别:
机电信息学院
专业名称:
电气工程及其自动化
学生姓名:
学号:
指导教师姓名、职称:
完成日期 2011 年 12 月 8 日
论文题目:变压器励磁涌流抑制控制器设计
专业:电气工程及其自动化
本科生: 文晨(签名)
指导教师:李忠(签名)
摘要
当变压器空载合闸或外部故障切除后电压恢复时,由于铁芯饱和会产生很大的励磁涌流,在最不利的情形下,可达到到正常励磁电流的上百倍,或者说可达到变压器额定电流的5一7倍。这一大大超过正常励磁电流的空载合闸电流称为励磁涌流。励磁涌流的大小和衰减时间与外加电压的相位、铁芯中剩磁的大小和方向、电源容量的大小、回路的阻抗、变压器容量的大小和铁芯饱和程度轶芯的剩磁以及合闸时的相角等因素有关。同时,在变压器空载合闸这一瞬变过程中,电流、电压的波形也会发生畸变,产生谐波;在一定的条件下,还可能会引起电力系统谐振,产生过电压。
变压器差动保护动作正确率长期偏低的一个主要原因是励磁涌流的存在。而识别励磁涌流有很多方法,由于受变压器铁芯材料磁饱和点的降低、TA暂态饱和等诸多因素的影响,其可靠性可能大幅降低。因此有待研究一种可靠性更高的识别,抑制励磁涌流的新方法。
本文利用MATLAB软件的仿真平台,在变压器各种运行情况下进行计算机仿真,并对所产生励磁涌流的特点进行分析。基于这些仿真分析,提出抑制变压器励磁涌流的方法,并且对于这些方法进行仿真分析,确实这些方确实简单易行。
关键词:变压器;励磁涌流;励磁涌流抑制;差动保护
Subject :Transformer inrush current suppression controller design
Specialty :Electrical system and automation
Name: wen chen (signature)
Instructor:li zhong (signature)
Abstract
When closing or external transformer no-load voltage recovery after fault clearing ,As the core saturation will have a huge inrush current ,In the worst case, can reach to a hundred times the normal excitation current, or up to the rated current of the transformer 5 to 7 times .This greatly exceeds the normal no-load excitation current is called inrush current closing .Inrush current size and decay time and the applied voltage, phase, iron core in the size anddirection of the remanence, the power capacity of the size of the loop impedance, the transformer core saturation capacity of the size and extent of Yi and closing at the core of theremanence the phase angle and other factors .Meanwhile, the transient in the transformer no-load closing process, the current and voltage waveform distortion can occur, resulting in harmonic ;In certain conditions, may also cause power system resonance, resulting in over-voltage .
Transformer differential protection accuracy is a major cause of long-term low inrush currentexists .And there are many ways to identify the izing inrush current, the ic material due to tr