Application of distance relay for distribution system monitoring

The traditional distribution network is primarily composed of radial feeders, designed for unidirectional power flow. Therefore, many operation regulation, protection and control system, in distribution network, are based on the radial distribution systems assumption. The integration of decentralized renewable sources will create a multidirectional power flow condition in the distribution grid which was originally designed for unidirectional power flow only. Integration of that active element increases the importance of new distribution system monitoring. In addition, based on the distributed generation interconnection of some utilities, over current protection is not sufficient for feeder protection in presence of renewable energies integration. Therefore, it is recommended to install a distance relay as the main protection of feeder. This paper presents using the distance relay not only as a protection device, but also as a monitoring tool at presence of renewable energies.