Modeling of Polarization in Oil-Paper Insulation Using Recovery Voltage Measurements

The state of the oil-paper insulation is a key factor for assuring a reliable operation of power transformers. Recovery voltage measurement is one of the methods utilized to estimate the polarization spectrum. Analysis of the polarization spectrum is used to evaluate the condition of the insulation with respect to moisture content and aging. In this paper, the elements which represent a polarization process are determined from recovery voltage measurement test results by using a new method based on genetic algorithm. The method was successfully tested on a simple circuit and then applied to two power transformers located in hydropower plants.