Linhas de transmissão não compensadas: manobra controlada considerando a correção da resposta do TPC.

Abstract

This work presents a recursive digital filter to rectify the Coupling Capacitor Voltage Transformers (CCVT) secondary voltage, with the purpose of correctly estimate the polarity of the trapped charge onto an uncompensated line and allow the application of controlled switching techniques. Overvoltages in transmission systems cannot be totally avoided, but their effects can be minimized. The analysis of the techniques available to mitigate these surges is extremely important for enhance the quality of energy. The controlled switching of transmission lines eliminates the need for pre-insertion resistors. While the electrical performance of two solutions is similar, controlled switching has become an economical solution for the lowest initial costs and increases the reliability of the circuit breaker due to the reduced number of moving parts. Controlled Switching of transmission lines requires measurements of its primary voltages. These voltages are obtained from existing Coupling Capacitor Voltage Transformers on the busbar. In steady state, the voltage obtained from the secondary of a CCVT is a replica of the voltage applied to its primary. However, the performance of this equipment is not ideal when subjected to transient situations or for measuring DC voltages. These inaccuracies may cause the closing of the circuit breaker contacts at the instant when the polarity of the line voltage may be the opposite of that last seen by the controller. As a consequence, high levels of surge can be achieved. Case studies using data from Brazilian Power System Grid will be simulated by Alternative Transients Program (ATP). The analyses are based on data obtained from electrical systems in service and on the performance of the filters. According to the results indicated that the insertion recursive digital filter reduce measurement errors caused by the CCVT when subjected to transient conditions, thereby improving the performance of the controlled switching.