Inclusão de proteção contra colapso de tensão de sistemas de potência em relês de subtensão

Abstract

In recent decades it has been observed the occurrence of voltage collapse phenomenon in several electric power systems around the world. This can be explained by the increase of generation to meet growing consumption without concomitant investment in transmission lines. It is usual to increment the active power transmission capability through the inclusion of reactive support devices. Due to excessive use of this resource, the load busses can become too capacitive. This implies in increase the risk of voltage collapse in these busses, even without transgressing the undervoltage limits. In this scenario the voltage collapse may occur without the actuation of a undervoltage load shedding scheme. In this case it is necessary to improve the undervoltage relay which can be achieved by the inclusion of a load shedding logic based on a voltage collapse proximity indicator. This work proposes a load shedding algorithm based on bus loading margins. In the context of electric power system protection, such methodology should be included in undervoltage digital relays that operate in load busses with capacitive power factor. The operation of the proposed algorithm is illustrated through simulations of situations favorable to voltage collapse using a reduced electric power system, represented by the Thevenin equivalent circuit coupled to a load bus, as well as the IEEE 14- bus power system.