直流偏磁下变压器运行状态量化评估方法

Quantitative state assessment method for transformer under DC bias

针对现有的变压器状态评估方法难以有效量化直流偏磁及其持续时间对变压器状态影响的问题,在分析直流偏磁下变压器振动强度、噪声、油温温升的变化规律的基础上,结合专家知识,采用降半柯西分布函数建立了直流偏磁下振动加剧的量化评估模型,采用指数分布函数建立了直流偏磁下噪声增加的量化评估模型,采用降半正态分布函数建立了直流偏磁下油温温升增加的量化评估模型。采用层次分析法(AHP)对3种量化评估结果进行综合,形成了考虑直流偏磁持续时间的变压器状态评估修正因子,实现了对直流偏磁影响的量化,为制定相应的应对策略提供技术参考。通过实例验证了所提方法的合理性。

Aiming at the problem that it is difficult to effectively quantify the influence of DC bias and its duration on transformer state by existing methods for transformer state assessment,based on the change law analysis of the vibration intensity,noise and oil temperature rise under DC bias and combined with the expert knowledge,a quantitative evaluation model of vibration aggravation under DC bias is established adopting the semi-Cauchy distribution function,the quantitative model of noise increase under DC bias is established adopting the exponential distribution function and the quantitative model of oil temperature increase under DC bias is established adopting the semi-normal distribution function. AHP is used to synthesize the results of the above three kinds of quantitative evaluation,and the correction factor of transformer state assessment considering the duration time of DC bias is formed,which can quantify the influence of DC bias and provide technical reference for making the corresponding countermeasures. The correctness of the proposed method are verified by case study.