变压器在谐波条件下的损耗及热问题分析-电气工程专业论文.docx

华北电力大学硕士学位论文 Ⅰ 摘 要 谐波是影响电能质量的稳态扰动之一。现代电力系统中，电力电子技术的发展、 电气化铁路的发展以及工业电器的大量使用使得注入电网的谐波日益增多，对电能 质量产生严重危害。变压器在电力系统中占有重要地位。目前，变压器在电力工程 的各个领域中获得了广泛的应用，由于技术上与经济上的原因，变压器的单台容量 越来越大，因此变压器的损耗及热点、温升更加引起人们的注意。电力系统的谐波 会使变压器铜损和杂散损耗增加，外壳、外层硅钢片和某些紧固件发热，还会造成 变压器噪声增大、降低变压器额定容量、降低设备寿命及可靠性等。因此研究谐波 对变压器损耗及温升的影响具有重要的现实意义。 本文分析了谐波在变压器中产生的磁滞损耗、绕组损耗及涡流损耗等，应用变 压器电磁场理论以及有限元分析理论，通过建立变压器三维模型，进行变压器的??? 磁场分析，对变压器铁芯、绕组的磁场分布、谐波损耗及温升进行计算分析，得出 变压器损耗及温升与谐波次数的关系，铁芯主通道轴向磁场密度分布情况，绕组及 铁芯的热点分布情况等，这对于减少变压器损耗、延长变压器使用寿命、保障电力 系统安全稳定运行具有重要意义。 关键词：变压器；谐波；损耗；温升 Ⅱ Abstract Harmonic is one of steady state disturbances which can influence the electric power quality.In the modern power system,with the development of power electronic technology and electrified railway and the extensive use of industrial electrical equipment,more harmonic are get into the power system,and bring serious consequences to the electric power quality.Transformer plays an important role in the power system,and has accessed to a wide range of applications in every domain of electric power engineering.Because of the reason of technology and economy,single capacity of the transformer become bigger and bigger,thus more attention is bring up to the loss,temperature rise and the hottest of transformer.The harmonic current of power system can make the transformer’s copper loss and stray loss increases,the outer shell, silicon steel sheet and some fasteners fever,and can cause transformer noise increases, reduce transformer rated capacity,life and reliability.Therefore analysis of harmonic loss and thermal problems on transformer has the important practical significance. This thesis analyzes the winding loss,hysteresis loss and eddy current loss in transformer caused by harmonic generation.With the theory of electromagnetic field in transformer and the finite element analysis theory,we make an analysis on the magnetic leakage in transformer,and the magnetic field distribution, harmonic loss and temperature rise of transformer iron core, winding and o