运行电力变压器内部的热点温度直接影响其使用寿命和运行可靠性.为准确评估电力变压器内部过热故障的严重程度,文章借助焓变理论提出一种计算故障能量系数的方法,为故障赋予一定的权值系数;并基于能量系数这一概念,以电力变压器各类不同程度的热故障为研究对象,建立其严重程度分级评估基准,此基准是以563组电力变压器热故障油色谱分析数据所计算出的能量系数值作为样本数据,利用最大熵原理得出最符合实际分布的电力变压器热故障能量系数概率分布函数,并求取其分位值Q20、Q70和Q95作为热故障严重程度的分级评估值.经实际算例分析,采用文中所提方法,不仅可以实现对热故障严重程度的量化评估,还可以合理地划分其严重等级,可为检修人员制定和执行维护计划提供参考.
The hot spot temperature inside the operating power transformer directly affects its service life and operational reliability.In order to accurately evaluate the severity of the internal overheating fault of a power transformer,this paper firstly used the theory of enthalpy change to propose a novel method for calculating the fault energy coefficient,and as-signed a certain weight coefficient to the fault;Secondly,based on the concept of energy coefficient,different degrees of thermal failures for various types of power transformers were the research objects,and the severity level evaluation criteria were established.This benchmark was based on the energy coefficient values calculated from the chromatographic analysis data of the 563 groups of power transformer thermal faults as the sample data,and the principle of maximum entropy was used to obtain the most consistent actual distribution of power transformer thermal fault energy coefficient probability distri-bution function,and the quantile values Q20,Q70 and Q95 were calculated as the graded evaluation value of the thermal fault severity.Finally,the method proposed in this paper could not only realize the quantitative assessment of the severity of thermal faults,but also reasonably divide the severity levels through analyzing the actual calculation examples,which can provide references for maintenance personnel to formulate and implement maintenance plans.