The Effect of Network Reduction on Overcurrent Relay Coordination in Interconnected Power Networks

Network reduction due to the lack of information of adjacent networks or limitations imposed by software is an inevitable task in interconnected power networks (IPN). The equivalent network (reduced network) is important since it can affect the entire simulation. While the effects of network reduction on the load flow and steady state conditions have been studied, the consequences of the network scale-down on the setting and coordination of protective devices have not. In this paper the effect of static network reduction approach on the setting and coordination of overcurrent (OC) relays is discussed to Figure out whether reduced networks can be used for OC relay setting calculation and coordination studies. The Ward method is applied to reduce the network and the OC relay optimal coordination method is used to find the OC relay time setting.