Patent ID: 11885843
Assignee: HITACHI ENERGY LTD
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 4:
5. The method according to claim 1, wherein the instantaneous comparison voltage value specified by the operation criterion of the protection device is calculated by:
determining the instantaneous comparison voltage value between the first phase and the second phase of the three-phase transmission line of the power transmission system, based on:
the sampled value of the current between the first and second phases at the measurement point;
the resistance value of the resistor and the inductance value of the inductor in the time-domain lumped parameter model; and
a differential value of the sampled value of the current between the first and second phases at the measurement point; and

determining the instantaneous comparison voltage value of the first phase based on:
the sampled value of the current of the first phase at the measurement point;
the resistance value of the resistor and the inductance value of the inductor in the time-domain lumped parameter model;
a proportion of the zero and positive sequence resistances of the three-phase transmission line;
the zero sequence current; and
a differential value of a combination of the sampled value of the current of the first phase at the measurement point, a proportion of zero and positive sequence inductances of the three-phase transmission line, and the zero sequence current.