Substituição de transformadores de potência em subestações de energia: uma estratégia global

Abstract

The knowledge of the operating conditions of power transformers in substations is of great relevance to the power system in order to improve their reliability. From the point of view of the concessionaires, it is necessary to promote better investment planning, helping in decision-making to replace and maintain these equipments. Therefore, this work has the objective of developing a new global methodology, through a multicriteria analysis, to verify the operating conditions and the importance of the power transformers currently installed in the high voltage substations. This methodology concomitantly considers the characteristics of life cycle (failure risk factor) and systematic importance (impact factor) of these equipments for the system in the process of prioritizing the replacement of transforming units. To achieve this objective, an analysis of the structural importance of each transforming unit for the system in which it operates is performed through composite reliability indexes (hierarchical level NH2 - generation / transmission). Additionally, a new methodology for calculating the Health Index for power transformers, practicable to different realities of Brazilian energy concessionaires, is used in this work. In addition, an analysis of the additional aging to which the transformer is being subjected is performed, based on the operating conditions of these equipments, such as loading curve, ambient temperature and physical characteristics of the transforming unit. Finally, the classification of the need for power transformers replacement is carried out with the aid of the multicriteria Analytic Hierarchy Process. In order to evaluate the performance of the methodology, power transformers were ranked through the proposed multicriteria methodology and only through the calculation methodology of the Health Index used in this work. The results demonstrate the importance of considering not only the risk of equipment failure, but also the systemic relevance of the transforming unit in the system in which it operates, in the process of prioritizing the replacement of power transformers in power substations.