Device to change the current density and direction in twin lines of suspected high voltage direct current transmission (HGV) interconnectors

摘要

1335245 HVDC power transmission BROWN BOVERI & CO Ltd 19 April 1971 [25 March 1970] 24998/71 Heading H2F In a multi-station HVDC network a pair of anti-parallel controlled rectifiers 7, 71 are included in one of the D.C. lines 19 between a rectifier 2 and an inverter 1, control circuits 17, 171 being provided to determine which of the auxiliary controlled rectifiers 7, 71 is to be operative and to control its voltage output so as to determine the magnitude and direction of current flow in line 19. As described the magnitude and direction of current is monitored at 14 and compared with a desired maximum current Imax. Only signal +# I due excess current passes diode 161 to controller 16 which determines the firing angle of one of the two gridvoltage controllers 17, 171 selected by relays 20 and 201 in dependence on the direction of current + I in the line. If the rate of change of current + I is excessive, e.g. if the current falls to zero, circuit 21 arranges the other controlled rectifier 7, 71 to become conductive. The auxiliary controlled rectifiers 7, 71 may comprise a plurality of series-connected rectifiers some of which may act as inverters and may be supplied from individual transformers or from an auxiliary winding on the transformers feeding the main rectifier 2. Quick-acting by-pass switches (not shown) may be provided to short circuit the auxiliary rectifiers 7, 71 in the event of breakdown.