Fault Analysis and Protection System Design for DC Grids by Abhisek Ukil & Yew Ming Yeap & Kuntal Satpathi

Author:Abhisek Ukil & Yew Ming Yeap & Kuntal Satpathi
Language: eng
Format: epub
ISBN: 9789811529771
Publisher: Springer Singapore

(6.13)

(6.14)

where, , and are the fixed setpoint (in ) of the magnitude of at , and respectively. Thus, either only the or , and can be used. This depends on the system and its requirements.

Fig. 6.8Variation of the STFT magnitude at Hz as the Hanning window progressively captures the fault current signal

Similar response is observed when STFT is applied on fault current signals. A low impedance fault current with fault resistance of 0.1 and the corresponding is illustrated in Fig. 6.8. It can be seen that magnitude of at 625 Hz is lowest in the pre-fault current. However, the magnitude of at gradually increases after 0.2, 0.4, 0.6, 0.8, 1.0 ms... of encompassing the fault current signal by the window function.

As STFT quantifies the frequency content of the signal present within the length of the window, it also quantifies the magnitude of ripple contents present in the signal. Thus, it is essential to understand to the selection of window length and window function and subsequently determining the selection of tripping thresholds for such fault detection method.

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