Coordination of overcurrent relays in microgrids according to the input and output of resources

In this paper, the directional overcurrent relays are adjusted according to the input and output of resources in the microgrid. Changes in the network structure will change the performance of the relays, so they will cause interruptions and thus reduce the reliability of the network. In the method used, by considering the injection of a virtual current according to the source isolated from the system, an attempt has been made not to change the initial settings of the directional overcurrent relays. Accordingly, using a telecommunication platform, all the required information is sent to the relays, and the relays, due to the presence or absence of sources, have a virtual value equal to the amount of short-circuit current of the separated or added sources in a soft way. They receive hardware, and this prevents the relay settings from changing to the original state where all resources are in service. The method used in an IEC microgrid with different generation types and in different operating modes and with respect to the presence or absence of short circuit power supplies, has been investigated.