| Abstract: | Transformer Differential and overcurrent schemes are traditionally used as main and backup protection respectively.
The differential protection relay (SEL487E) has dedicated harmonic restraint function which blocks the relay tripping
during the transformer magnetizing inrush conditions. However, the backup overcurrent relay (SEL751A) applied to
the transformer protection does not have harmonic restraint element and trip the overcurrent relay during the inrush
conditions. Therefore, major contribution of this research work is the developed harmonic blocking scheme for
transformer which uses element (87HB) of the transformer differential relay (SEL487E) to send an IEC61850 GOOSE-based
harmonic blocking signal to the backup overcurrent relay (SEL751A) to inhibit from tripping during the transformer
magnetizing inrush current conditions. The simulation results proved that IEC61850 standard-based protection scheme is
faster than the hardwired signals. Therefore, the speed and reliability of the transformer scheme are improved using the
IEC61850 standard-based GOOSE applications. |
