An Effective Signature for Detection of Flicker Sources in Transmission Networks Using Fast Fourier Transform

Before taking any action for reduction of flicker negative impacts, it is essential to identify the main contributors of flicker in the network. This paper proposes an effective signature, by which one can determine whether a flicker source is connected to a specified bus of the transmission network or not. Hence, it will be useful for rectifying disagreements between network operator and industrial consumers about flicker generation. The proposed signature is extracted from complex power angle versus frequency diagram for a specified bus of the network. This diagram is achieved by performing fast Fourier transform (FFT) on three-phase measurements of the bus voltage and load feeder current. Based on simulation results presented for a standard test system, it is shown that in case a flicker source is connected to a specified bus, this diagram has mirror symmetry around the system operating frequency. Moreover, relative extrema of this diagram occur at side frequencies that differ from the network operating frequency by the flicker source frequency. Hence, the proposed signature is also helpful for evaluating the frequency content of the flicker source.