Abstract of Thesis presented at COPPE/UFRJ as a partial fulfillment of the requirements for the degree of Master of Science (M.Sc.)

Modeling and Optimization of Power Transformers' Maintenance Scheduling

Christian Ducharme

July/2012

Advisor:

Alexandre Pinto Alves da Silva

Department:

Eletrical Engineering

      Lately in Brazil, the quality of of the electrical energy transmission service has been measured by the availability and capacity of its facilities, which has granted the the maintenance division of transmission companies a leading role – planning the maintenance program of their facilites, mainly in relation to power transformers, so as to assure that the required shutdowns will result in the lowest possible number of fines issued to the company. This paper aims at proposing a model for the power transformers’ maintenance program in order to optimize their outage schedule and to minimize costs and risks arising therefrom. The methodology evaluates the importance of each transformer, the maintenance costs, the benefits of the best time for an intervention, and takes into consideration the main restrictions present in a maintenance program. The problem was mathematically modeled as a Mixed-Integer Linear programming problem and we have employed the algebraic modeling language in order to apply the proposed model in a computational tool. To this end, data of the 2010 Brazilian electric system was used for building up the historical background and 2011 data was employed to test the effectiveness of the model. The output argument of this tool is the optimum viable arrangement for the maintenance schedule of a power transformer population within a 52-week timespan. This result represents an innovative, robust and empirical-based solution, which adequately supports the experts’ decision-making process. The use of such solution allows a greater control of the variables involved and lowers risks for the company.