电力变压器是电力系统中重要的设备之一.doc

摘 要 电力变压器是电力系统中重要的设备之一，其安全运行直接影响着供电的安全性和可靠性。所以判断在故障电流作用下，变压器绕组是否会发生变形、变形程度是否会影响变压器的安全运行，是一项非常重要的任务。 频率响应分析法（简称FRA）是一种通过分析系统频率响应来分析系统特征的方法。近几十年，频率响应法在分析变压器绕组变形的研究中已渐渐成为一种重要的诊断方法。本文的主要内容是探索频率响应法中变压器的频响特性。为了了解尽可能大的频率范围内绕组参数和电磁场特性，我们的仿真是在50Hz~10MHz频率范围内进行的。 目前对绕组变形的分析方法主要是基于对其幅频响应曲线的分析。本文总结了前人变压器频率响应的方法和经验，对其不足之处作了更进一步改进细化，用Ansoft－Maxwell软件分大小尺度对变压器绕组和铁心参数进行仿真计算。在小尺度中，充分考虑集肤效应和邻近效应的影响，把绕组和铁心导电性能、导磁性能的频率特性等效为等效电导率和磁导率随频率的变化,细致地研究变压器绕组和铁心的等值参数的频率特性；在大尺度中，求解绕组的RLC等值参数。然后以此为基础构建了变压器的RLC等值网络模型，通过用Matlab求解矩阵电路方程，从而求取变压器的频响曲线。 关键词： 变压器，绕组，等值参数，仿真，频率响应分析法 ABSTRACT As one of the most important electrical equipment, whether can the Power transformers work safely influences the system’s security of the electrical grid directly. So how to know whether the winding of the Power transformers is out of shape or whether the winding shape is under control is very significant. Frequency response analysis (FRA) is a method of system characterization by analyzing its frequency responses. During the past few decades, application of this FRA for power transformers has evolved as a diagnostic tool. Here the main task is to study the frequency characteristics of power transformer for FRA. We discuss the results of the calculations performed in the frequency range 50 Hz–10 MHz and show that the largest variations of both the magnetic field and parameters of the windings. At present time, the method of monitoring winding shape is basic on FRA. After summarizing the experience and method, I improved some parts to make the model better. My progress made with the software named Ansoft-Maxwell is divided into two computation parts, which are small-scale and large-scale. In small-scale part, the power transformers model is computed with considering the skin effect and proximity effect. We contribute the varying of resistance and inductance depending on frequency to the parameters of power transformers changing with frequency. After getting the effective parameters of power transformer winding in sm