Comparison of maintenance scheme effects on power transformer reliability performance

Power transformer failures have a significant impact on electrical systems reliability, as they compromise the electricity delivery. Failures impact the operational cost of electric utilities as they endanger the accomplishment of power commitments. Power transformer failure rate can be modeled from its health condition, which is determined from different condition parameters. This paper is aimed to compare different maintenance schemes that allow the asset to be available the longest possible time. The power transformer operation is represented considering actual electric load profiles and temperature. Electrical and thermal transformer parameters are taken from manufacturer tests and technical standards. An electrical-thermal model is employed to estimate the life span reduction and temperature changes. From life span and loading, the health condition is determined, so as the effects of different maintenance schemes. The failure rates are calculated for unmaintained conditions and different maintained schemes, allowing to determine their effects on transformer reliability. Optimal maintenance schemes are determined and the expected benefits in failure rate reduction, asset reliability and life span extension are presented. As a result, it was found that certain time-based maintenance schemes provide better transformer reliability performance in comparison to condition based schemes, allowing to reduce the interruptions andextending the life of the transformer. Las fallas en los transformadores de potencia tienen un impacto significativo sobre la confiabilidad de los sistemas eléctricos, debido a que comprometen la prestación del servicio de energía. Las fallas impactan los costos operacionales de la energía debido a que ponen en riesgo el cumplimiento de los contratos de energía. La tasa de falla en los transformadores de potencia puede modelarse a partir de su condición de salud, la cual es determinada a partir de diferentes parámetros de condición. Este artículo apunta a comparar diferentes esquemas de mantenimiento que permitan tener el activo disponible el mayor tiempo posible. La operación del transformador de potencia es representada considerando perfiles reales de temperatura y carga eléctrica. Los parámetros eléctricos y térmicos del transformador son tomados de pruebas de fabricantes y estándares técnicos. Un modelo eléctrico-térmico es empleado para estimar la reducción de vida útil y los cambios de temperatura. A partir de la vida útil y la c