| 摘要 |
PCT No. PCT/SE97/00856 Sec. 371 Date Apr. 28, 1998 Sec. 102(e) Date Apr. 28, 1998 PCT Filed May 26, 1997 PCT Pub. No. WO97/45905 PCT Pub. Date Dec. 4, 1997An installation for power transmission by high-voltage direct current has at least two converter stations which are interconnected by a dc line (DC), at least one station (SR1) having a line protection device (LP) adapted to detect a ground fault on the dc line and, when a ground fault is detected, to achieve a reduction of the voltage (UD) and the current (ID) of the line and thereafter to make a restart attempt. The installation has, in addition, a detection circuit (FD) for detection of a permanent low-impedance ground fault on the dc line. The detection circuit is activated after an intervention by the line protection device. During a detection interval, the detection circuit causes one of the stations (SR1) to feed a current into the line. The detection circuit senses the line voltage, compares the growth of the line voltage with the corresponding expected growth in case of a faultless line and prevents a restart of the installation if the sensed voltage growth is smaller than the expected growth. |
