Fault detection Scheme for AC Microgrids based on Sum of Squared Relay Current and TKEO

The design of an efficient protection scheme for an inverter-based distributed generator (IBDGs) microgrid is a complex engineering challenge. An inverter has a low fault current property, and therefore, the conventional protection schemes are not appropriate to detect a fault in an inverter-based microgrid. This paper introduces a protection scheme that employed a Teager-Kaiser energy operator (TKEO) based concept to assessthe one-end current-based signal to detect the fault in the microgrid. The current-based signal is the sum of squared relay currents (SSRCs), evaluated at one end of the distribution line in the microgrid. During regular operation of the microgrid, the SSRC is almost negligible, whereas its variation is considerable in any possible disturbance. The TKEO is applied on the SSRC and based on various simulations, a fault detection index (FDI) is calculated. When FDI is more than the threshold, it is reported as an internal fault; otherwise, it is an external fault or other disturbance. With the help of a simulation study, the suggested protection scheme is testedfor different adverse conditions such as different fault types, fault resistances, fault locations, etc.Furthermore, numerous non-faulty events such as load switching, capacitor switching, and non-linear loading were also used to test the robustness and effectiveness of the proposed scheme. Moreover, the technique is also verified for fault during single-pole tripping. It is found that it can successfully detect the fault even in a two-phase system that indicates the accuracy and efficacy of the scheme.The findings reveal that the proposed approach is proficient in detecting faults in an inverter-based AC microgrid in various operating conditions.