Resumo:
Power transformers are directly related to the electrical system reliability and power companies are pressured to improve the quality of service provided. In this scenario, real-time monitoring presents a strategic advantage by providing alarms and information for diagnostic algorithms and asset condition. However, the associated cost still is a limiting factor in the dissemination of monitoring systems, especially for lower value transformers such as those in distribution substations. This work contributes to the real-time monitoring of transformers on two aspects. The first being the development of a partial discharge sensor based on the IEC 60270 electrical method, motivated by the fact that the transformer life is directly associated with the condition of its insulation system and, according to the literature, approximately 36% of transformer failures are of dielectric origin, and the partial discharge measurement presents as one method for evaluating the condition of this system, since they are indicative of incipient defects and present an accumulative behavior. The developed sensor was submitted to laboratory tests to guarantee the operational safety of its application in 06 transformers of 145 kV for online monitoring and, also, it was used to measure partial discharges in a transformer with formation of combustible gases. The second contribution is a methodology for prioritizing investment in monitoring systems for distribution power transformers in the Brazilian regulated energy market, considering that for the monitoring of all subsystems of a transformer, other sensors are needed together with the partial discharge sensor developed in this work. This methodology considers the technical, technological, and regulatory dimensions and was implemented for a population of 848 transformers.
