Adaptive protection coordination scheme for power networks under penetration of distributed energy resources

Integration of distributed energy resources in power networks make them interconnected and active. Depending upon the type, short circuit capability and location of distributed energy resource in transmission and distribution systems, design of protection coordination schemes becomes very challenging. Complexity further increases in the design of protection coordination schemes, when penetration effect of these resources reaches to upstream transmission lines and coordination among the distance and over current relays requires a review. The protection coordination scheme discussed in this article monitors the state of power network continuously. Depending upon the operational topology of the network, time dial settings as well as plug settings of over current relays and zone-2 setting of distance relays are selected from pre-optimsed relay group settings. Whenever there is any change in the network fault level either due to change in line parameters or incoming of new distributed energy resource, new relay group settings are communicated to corresponding relays. The proposed protection coordination scheme is implemented in RSCAD software for modified eight bus test bus and modified IEEE14 bus system. It is observed that the proposed protection approach is highly flexible to maintain the coordination among the over current and distance relays.