| 摘要 |
Protective relay with selective phase selection in electric power distribution systems with double transmission lines between two stations (TP,TM) and with the ends of the two lines being connected to a common busbar station in each station. The protective device comprise a protection unit, terminal, at both ends of each line. All the terminals (M1,M2,P1,P2) comprises an identical basic design comprising measurement of phase quantities (17), filtering (18) and A/D conversion (19). Furthermore, the identical part comprises a parameter estimator (20) for Fourier series expansion of measured phase signals and generation of the respective residuals. The parameter estimator cooperates with a frequency estimator (21) and a sampling regulator (22). Each basic design also comprises a local logic unit which, by means of a transient and steady state analysis, finds out whether an event on the network is due to a fault or a connection/disconnection of the phase/line and the current direction at each terminal. At one of the terminals, at both stations, there is a station master unit (26) which compiles all information for the station in question, calculates the distance to a fault, etc.. For final decisions as to whether a recorded fault lies between the stations, as to faulty line(s) and phase(s), all information from the two stations is compiled in a superordinate unit (29) in one of the terminals at one of the stations. |
