Application of modified all-phase FFT to extract signals in microgrid for condition monitoring and control purposes

Microgrid with multiple grid-connected inverters produces abundant harmonic voltage and current components. Such harmonics make it difficult to extract fundamental component and other useful components. Accurate yet time-efficient algorithm is in high demand to solve this problem not only for producing accurate reference signals but also for fulfilling effective control and event detection in microgrid. This paper adopts a modified all-phase FFT method for accurate extraction of both magnitudes and phase angle of signals in a microgrid. Such algorithm is tested by using synthesized signals and its efficacy is pronounced compared with conventional FFT. Furthermore a microgrid test system is built in Simulink to validate the effectiveness of proposed algorithm. It is found that even under harsh circumstances, the proposed algorithm still works effectively. By detecting a number of harmonic components, one can effectively detect events in power system, such as inverter switching-in and arcing fault happening. All this information is necessary input into a power and data management centre that manages the microgrid for a reliable and efficient operation.