1 Corresponding author: Om Hari Gupta E-mail: omggupta@gmail.com Received: July 16, 2025 Revision Requested: September 13, 2025 Last Revision Received: October 2, 2025 Accepted: October 23, 2025 Publication Date: February 5, 2026 DOI: 10.5152/electrica.20

Abstract

It is quite challenging to protect AC microgrids that operate in both islanded and grid-connected modes due to the large differences in fault currents between the two modes. Microgrid protection is a challenging task, as traditional overcurrent relays do not function effectively with integrated renewable distributed power due to the bidirectional flow. When it comes to power supply, solar-based distributed generators (DGs) are quite reliable; however, when they are integrated with inverters, the fault current is limited, making protection challenging. This article proposes a novel protection scheme that uses differential current followed by a Teager Kaiser Energy Operator with a dual filtering method. The scheme is able to detect faults with high impedances up to 1000 Ω in grid-connected mode and 500 Ω in islanded mode. The scheme was also tested for load switching, capacitor switching, nonlinear loading, and DG outages and is able to differentiate between the non-fault transient events and fault events. The scheme’s efficiency was checked in radial and mesh configurations. The scheme is able to detect faults within 1.3 ms. Rigorous simulations were conducted to validate the scheme’s efficiency, including evolving faults, simultaneous faults, and composite faults. The scheme performed very well in detecting these faults.

Cite this article as: T. N. Mahato, S. Ansari and O. H. Gupta, “A Teager Kaiser energy operator–based novel differential energy technique for the detection of very high impedance faults in AC Microgrid feeder,” Electrica, 26, 0197, 2026. doi:10.5152/electrica.2026.25197.