| 摘要 |
A three-region current differential protection method belongs to the technical field of current differential protection in electric power systems. The method comprises: determining a region on an amplitude-phase plane to which the relative relation of double-end currents belongs and the type of faults, respectively, and then on the basis of the determination results of the both, determining whether or not protective actions are performed. The amplitudes and phases of the double-end currents are fully utilized; the whole amplitude-phase plane is divided into three regions, including a brake region, a fuzzy region and an action region; whether the protective actions are performed or not is determined according to which region the relative relation of the double-end currents is in; and in the fuzzy region, external fault CT linear region criteria are employed to distinguish internal high-resistance faults from external fault CT saturation, thus the contradiction between sensitivity and safety is eliminated, and meanwhile, there is a good quickness in the action of transforming an external fault into an internal fault. |
