Islanding Detection Method for Grid-Forming Inverter by Reactive Power Injection

Abstract

The operation of grid-connected inverters in islanding presents critical issues for grid operation, utility workers' safety, and stakeholders, due to the control of voltage magnitude and frequency, reconnection caused by phase mismatch, among others. In such cases, grid-following inverters can detect islanding due to their current source operational characteristics, whether they are supplying 100% power or not. However, grid-forming inverters, during islanding with droop control, supply power at a frequency lower than the grid frequency under load, and cannot detect islanding when not supplying power due to their voltage source operation mode. To overcome this limitation of grid-forming inverters, this paper proposes a method to detect islanding by injecting reactive power into the power command of the droop controller. The method is validated through simulations in a 380V/60Hz system using PSCAD/EMTDC. © The Institution of Engineering & Technology 2024.