Load blinding stabilisation for DOC relays subjected to reverse load flow

The evolution of modern power systems has seen an increase in the generation at the distribution end of the system, thus bringing to an end the uni-directional power flow of traditional systems. Reverse load flow from distribution to transmission is now becoming more common, which is problematic for the DOC (directional overcurrent) protection which could mal-operate if the exported load exceeds the current threshold. This presentation discusses the use of load blinders to prevent mal-operation of the DOC relay during export conditions, whilst maintaining maximum sensitivity for resistive faults on the sub-transmission network.