Patent ID: 11887774
Assignee: nan
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H | IPC H

Claim 10:
11. A system for differential protection of a transformer under geomagnetically induced current (GIC), the system comprising electrical circuitry to execute:
a harmonic-based GIC detection module to receive differential currents associated with the transformer, and output a high GIC signal where second harmonic phasors of the differential currents are in a negative-sequence format and at least one magnitude of the second harmonic phasors is greater than a magnitude threshold, or waveforms of three phases of the differential currents are all asymmetrical in a positive or negative direction, otherwise outputting a low GIC signal;
a supplementary module to determine derivatives of the differential currents of three phases of the transformer, output a high supplementary signal where at least one of the derivatives of the differential currents is greater than a supplementary threshold, otherwise outputting a low supplementary signal, and combine the GIC signal with the supplementary signal using NAND logic to determine a supplemented GIC signal;
a second harmonic blocking module to combine the supplemented GIC signal with a second harmonic blocking signal using AND logic to determine a supplemented second harmonic blocking signal; and
a trip request module to output a trip signal for electrically tripping the transformer based on the supplemented second harmonic blocking signal.