Adaptive Coordination of Overcurrent Relays Considering Setting Changes Minimization to Improve Protection System's Reliability

The dynamic behavior of active distribution networks has caused a lot of difficulties for the conventional coordination between protective devices. To overcome these coordination challenges, adaptive protection schemes (APSs) are provided as a solution. APS can protect different network states (NSTs) by changing settings where it is needed. Frequent change of APS' settings increases the possibility of applying wrong settings to the relays. In this paper, an algorithm is proposed to reduce the number of setting changes in a Setting Group based APS. By reduction of setting changes, the possibility of applying wrong settings is reduced and as a result, the APS' reliability is improved. Applying the restriction on APS' settings results in longer operation times of relays. A Multiobjective optimization algorithm is proposed to show the relation between the total protection time of main protective relays and the number of setting changes of APS and select preferred settings.