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

Interaction Between Power Autotransformers and High Frequency Applications of Electric Power System

Carlos Magno Rodrigues Vasques

October/2011

Advisors:

Luiz Pereira Calôba Helvio Jailson Azevedo Martins

Department:

Eletrical Engineering

      In recent years, failures in power autotransformers have been reported by Brazilian utilities, which are associated, in some cases, with the interaction between these equipment and electric power system.
      In this scenario, this work started from the investigations and measure information of on-site relating to stresses imposed on dielectric power autotransformers caused by switching of circuit-breakers and disconnectors during the insertion of power autotransformers bank in the electric power system. SFRA (sweep frequency response analysis) measurements were performed in autotransformers and instrumentation, beyond the evaluation of the methodology for measuring and monitoring of transient voltages from bushing capacitive taps of power.
      Based on the information of frequencies and amplitudes, of the switching in power substation, the following were evaluated: effect of the switching on the natural frequencies oscillation of the power autotransformers, estimation of the voltage transfer between the windings of power autotransformers and finally, the evaluation of the risk involved in the switching through the frequency domain severity factor (FDSF).