Adaptive coordination of overcurrent relays in active distribution networks utilizing a multi-objective optimization approach

Abstract

Digital Overcurrent Relays (OCRs) can store multiple Setting Groups (SGs) to be capable of protecting different network states (NSTs) by changing the activated SG of OCRs when it's needed. Therefore, in a network with a high number of possible topologies and a high penetration factor of Distributed Generations (DGs), the number of required setting changes rises. There is always the risk of applying wrong settings to the OCRs in case of NST changes. The risk of applying wrong settings to the relays rises by the increment of setting changes. In this paper, NSTs are grouped and protected by one SG of OCRs in a way that the minimum number of setting changes are used considering all possible configuration changes and DGs connection/disconnection. Doing so reduces the possibility of activating the wrong SGs in OCRs by decreasing the number of setting changes. In this paper, a multi-objective optimization algorithm is proposed to find the optimum operation point considering the number of setting changes, the number of SGs and total protection time. It has shown in the results that the number of setting changes has been reduced a lot by using this paper's method.