电力变压器是电网中的最重要的设备之一，利用它可以把不同电压的电网联结在一起，组成复杂的电网或庞大的电力系统，并在其中发挥着重要的作用；电力变压器的可靠性直接关系到电网能否安全、高效、经济的运行。由于变压器长期连续在电网中运行，不可避免地发生各种故障和事故，因而如何对电力变压器在运行中的故障进行诊断，已成为电力部门急需解决的问题。

IEC三比值法是电力变压器内部故障诊断的常用方法。IEC三比值法是经IEC审议后，在四比值法（即罗杰斯法）的基础上修改而得到的一种简化的新的比值方法，它是将变压器油裂解产生的CH4、H2、C2H6、C2H4、C2H2几种气体相互比较而得到一组数字编码，根据编码的不同组合可以分析得出变压器的各种故障类型。

IEC三比值是一种比较成熟的对电力变压器故障进行检测的方法，而且检测的精度相对较高，并不会象其他检测方法那样要求停机检测而影响变压器的工作，提高了电网的经济运行，也提高了工作的效率。因而，IEC三比值法在国际上得到广泛的应用。

在完成本次设计过程中，要求对电力变压器的内部故障进行广泛了解，并用VB语言对IEC三比值法进行故障诊断算法的程序设计，完成故障诊断模块和数据管理模块，实现变压器内部故障论断。

-Power transformer in the grid is one of the most important equipment, it can use the network of different voltage linked together, to form a complex network or large electric power system, and plays an important role in it　the reliability of the power transformer is directly related to the power grid safe, efficient, economic operation. Because the transformer long-term continuous in operation of power grids, inevitably occurs a variety of failures and accidents, so how to power transformer in operation fault diagnosis, has become urgent to solve the problem of electric power sector.



IEC three ratio method is the electric power transformer fault diagnosis methods. IEC three ratio method is the IEC deliberation, in the ratio of four (Rodgers method) based on the modified and get a new simplified ratio method, it is the transformer oil cleavage to generate CH4, H2, C2H6, C2H4, C2H2 several kinds of gases are compared with each other and get a group of digital coding, according to enc