| 摘要 |
PROBLEM TO BE SOLVED: To implement a protection relay device capable of avoiding occurrence of breaker trip unnecessary for a short time system accident, with a simple configuration.SOLUTION: Secondary current Is of a current transformer 40 whose primary current is current Ip of a power transmission line is converted to a voltage signal before passing through an analog filter 120, an A/D converter 130, and a digital filter 140 and being input to an accident detection unit 160. The accident detection unit 160 detects occurrence of an accident in a power system on the basis of magnitude of current shown by the input signal, and generates a trip instruction TP on a breaker installed on the power transmission line when the accident is detected. A short time accident detection unit 170 detects the occurrence of the accident in the power system on the basis of an input signal obtained by bypassing the digital filter 140, and turns on a restriction flag RL for restricting the generation of the trip instruction TP when accident duration time in the occurrence of the accident is shorter than a predetermined threshold. |
