| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to narrow a power failure range as much as possible by separating an accident section in a power plant without relying on a transmission line protection relay (so-called backup relay), in the case that a bus accident occurs when a bus protection relay stops its function.SOLUTION: A backup protection method for a bus protection relay comprises the steps of: detecting occurrence of a bus accident in the case that the bus accident occurs when a bus protection relay 31 stops its function (a first step); comparing a value of impedance based on current flowing on the side of a first bus 101 and that of impedance based on current flowing on the side of a second bus 201 where the buses sandwich a bus contact breaker 11, and determining that the accident occurs in a bus having a larger value (the first bus 101 or second bud 201) (a second step); and opening the bus contact breaker 11 when detecting the occurrence of the accident, and opening all breakers 111 and 112, or 211 and 212 which are connected to a bus (the first bus 101 or second bus 201) where the occurrence of the accident is determined (a third step). |
