STFT Filter Bank Based Islanding Detection Technique

Depleting coal reserves and increasing carbon emissions have propelled the use of renewable energy sources to generate electricity. Microgrids have been recognised as one of the solutions to provide continuity of power to critical loads even during natural disasters, as they can connect or disconnect from the main grid. The presence or absence of the grid is critical to the operation of the various inverter-based resources and load management in the Microgrid. Various active and passive methods have been proposed by researchers to detect islanding. This paper focuses on detecting the islanding condition based on the filter bank approach of Short Time Fourier Transform. The voltage at the interface of distributed generation was sensed and the amplitude of a particular frequency component was estimated using the filter bank approach. The estimated amplitude was then checked against a set threshold to detect islanding. The proposed islanding detection technique was tested and was found effective on a sample Microgrid for conditions like normal operation, operation during faults and operation during turning ON and OFF loads and sources.