Método de cálculo de fasores para linhas de transmissão com compensação em série.

Abstract

It is presented here the proposition of a phasor calculation method to be used in distance protection of capacitive series compensated transmission lines. The proposed method consists in the usage of cascades of non-recursive time invariant linear digital filters. The used filters were projected to eliminate oscillatory components with exponential decays. This kind of component is present in signals from transmission lines with the mentioned sort of compensation, and it is convenient to avoid its influence because it can cause wrong fault classifications as being in the protection zone. Other methods of phasor calculation existent in

the literature presented as suitable to series compensated transmission lines are based in non- linear methods and the usage of time invariant linear filters, as proposed in this thesis, is an

advantage because the analysis of the method is easier. The filter proposed in this thesis is stable, it has in some shown examples a compatible frequency response, and it has a compatible actuation time of distance protection. In some examples shown, the proposed method corresponds to an impedance trajectory with a reduced or absent spiral around the final value, when others methods proposed in the literature generate an expansive swirling trajectory. These examples are for short-circuits in the remote bus. It was noted that the proposed method has a better performance in determining whether the short-circuit belongs to the first protection zone in situations prone to a spiraling impedance trajectory around the final impedance calculated value.