| 摘要 |
PROBLEM TO BE SOLVED: To provide a protective relay method capable of avoiding an unnecessary operation caused by reverse power from a single-phase load. SOLUTION: Each phase voltage and current in three-phases power is detected at a power receiving point, in which a cogeneration system and a commercial power system are linked to each other. Reverse power in each phase is calculated (S2) on the basis of the detected each-phase output (S1). Whether the reverse power in each phase is concurrently detected or not is judged (S3). Then, the protective operation for the counter power is carried out (S4) if each reverse power in all three phases is concurrently detected. As a result, an unnecessary operation caused by reverse power from the single-phase load can be prevented. |
