Six-phase transmission line over current protection by numerical relay

Six-phase transmission line is an alternative solution for increasing the power transmission capability of overhead power transmission lines over existing rights of way. Double circuit three phase lines can be converted to six-phase transmission line. The idea of this new technique is very useful, but there are some protection problems due to complexity of the network. The modern Digital Signal Processor (DSP) embedded with numerical relays can improve the protection operation of the relays in six phase transmission lines. The numerical relays perform fast computing and process the signal with higher accuracy. This work presents new algorithm for numerical relay over current protection in a six phase transmission line. The numerical relay is simulated and tested using PSCAD, for single line to ground and three phase to ground faults on a six phase transmission line in a model system. It was observed that the numerical relay gives the best solution for complicated six phase transmission line protection.