Dimensionamento de MOV para proteção de bancos de capacitores série.

Abstract

This work shows the procedure for dimensioning the Metal Oxide Varistors (MOVs) of the Series Capacitor Banks (BCS) 05C5 and 05C6 located in the São João do Piauí Substation. The energies absorbed by each MOV are determined so that they are correctly sized to withstand short-circuit requests in the electrical system. The ATP (Alternative Transient Program) software was used to simulate the electrical system in the 2022 horizon as well as the electric scheme of the BCS and the protection control system, the latter using the TACS language. The level of short-circuit current and energy to which the MOVs can be submitted and which serve as a parameter to carry out BCS ¬by-pass or not is determined. For this, several faults were simulated in the system in order to adjust the protection for the most severe conditions and the performance of the found adjustment was evaluated. It was also compared the proposed adjustment with the current one and it was verified that the current adjustment will be obsolete for the system of the mentioned horizon. The parameters of activation of the Spark Gap by current were overcome, those of energy remained close to the current ones. The nominal energy of one of the MOVs in the Boa Esperança line - São João do Piauí found was about twice the previous value, while the MOV energy located in line 1 of the line between São João do Piauí and Sobradinho remained close to the value previous.