Abstract:
A high power d.c. breaker for connection into a d.c. carrying high-voltage line (L), has two normally closed and electrically series-connected mechanical breaks (BSI, BSII) adapted to be traversed by the line current (I) and to be opened for breaking the current. A capacitor (CB) is connected in parallel with the series connection of the breaks. A semiconductor member (HO) is connected in parallel with one of the breaks (BSI). Upon opening the breaks, a control member (SO) controls the semiconductor member such that a zero crossing of the current through the second break (BSII) is obtained, whereby the line current (I) is commutated over to the capacitor. (FIG. 1)
Abstract:
A method and a device in an electric power network (1), comprising an active filter (4) controllable via a control input (41), for reducing disturbances generated by a disturbance source (6) located in and/or connected to the power network. A control member (8) is adapted, based on at least one first state variable (Y1i) sensed in the power network (1) and a model of the power network (1), to calculate the disturbances (X2) which occur in a second section (B--B) in the power network (1) without action from the active filter (4), to calculate a control signal (C1) such that, supplied to the control input (41), it would generate in the second section (B--B) the calculated disturbances (X2) with reversed polarity, and to generate the control signal (C1) and supply this to the control input (41). By sensing, in addition, at least one second state variable (Y2i) in the second section (B--B), the control signal (C1) can also be generated in dependence on the control deviation (DU) of the second state variable (Y2i) from a desired value (Y2R). (FIGS. 1 and 2A)
Abstract:
A method and a device in an electric power network (1), comprising an active filter (4) controllable via a control input (41), for reducing disturbances generated by a disturbance source (6) located in and/or connected to the power network. A control member (8) is adapted, in dependence on the control deviation (DU) from a desired value (Y2iR) of at least one state variable (Y2i) sensed in the power network (1), to generate a control signal (C1) which is supplied to the control input (41). The control member (8) is adapted to transform the control deviation (DU) in a filter device (93) with a transfer function (FI) which simulates the inverse of the transfer function (F1') from the control signal (C1) to the control deviation (DU) and/or to filter the output signal of the controller in a filter device (943, 953, 956) without any phase shift. (FIGS. 1 and 10)
Abstract:
A power converter includes a plurality of thyristors, each of which is controlled by a control circuit. A multi-section voltage divider is connected in parallel with a thyristor and provides the control circuit with power as well as means for measuring voltage across the thyristor. The present voltage divider components minimize the space required and cost of fabrication.
Abstract:
A thyristor overvoltage protection circuit wherein an avalanche diode conducts to divert overvoltage energy from a thyristor to avoid self-ignition of the thyristor when the overvoltage reaches a particular level. A simulator circuit monitors the thermal loading on the conducting diode and activates an ignition pulse device if the thermal loading exceeds the safe operational range of the diode. The activated ignition pulse device ignites the thyristor so that the thyristor may divert the overvoltage energy and thereby discharge the diode.
Abstract:
A high voltage DC breaker apparatus configured to break a fault current occurring in a high voltage DC conductor includes a current limiting arrangement having at least one section with at least one semiconductor device of turn-off type and at least one arrester connected in parallel therewith, and a mechanical DC breaker connected in series with the current limiting arrangement and including a mechanical switch. The mechanical DC breaker is configured to enable breaking of a fault current in said DC conductor once said semiconductor devices of said arrangement have been turned off.
Abstract:
Contact means (4) related to a vehicle are adapted to comprise an elongated arm (50), one end portion (50a) of which is rotatably attached to the underside (bottom) of the vehicle (1) and the other end portion (50b) of which is adapted to support said contact means (4). One or more sensors (151a, 151b) are disposed at the vehicle (1) and are intended to be able to sense the presence of and the orientation of a track or groove (51) and transfer sensed information to a power control circuit (100), which is adapted to comprise a control circuit (100b), which when sensing the existence of and a sensed orientation of a track or groove (51), within a covered and restricted area, is to be adapted to actuate means (7) adapted to a sidewise movement and/or a lowering (or raising) movement at the contact means (4).
Abstract:
The present invention has its application to a vehicle-related arm-shaped contact means ((4)) related to a contact means arrangement as a current collector or system (“S”) for propelling an electrically, i.a. by batteries (“II”, B), propellable vehicle (1) along a roadway (2) comprising “a” a plurality of roadway portions (2a, 2a1), wherein said road portions are allotted at least one track or slit (51, 52), having introduced therein current supplyable conductors (4a, 4b), and “b” one or more powerable vehicles (1), with each vehicle exhibiting a control circuit (100, “R1”) adapted for necessary distribution of power, wherein said vehicle (1) is on its underneath side provided with a displaceable contact means ((4)) as said current collectors. Said current collector (41,41′) is shaped as a main portion (141), made of an electrically insulating material, and having a lower surface (142) facing towards the contact surface (4a′) being shaped flat, and having a lower contact surface (144) consisting of an electrically conductive material (160). The electrically conductive material (160) is adapted to extend through the main portion (141) for forming one or more upper contact surfaces (146a) and/or connecting conductors (146b).
Abstract:
A VSC converter includes in each valve one first semiconductor device of turn-off type with a voltage blocking capacity rating of a first, high level and connected in parallel therewith a series connection of a plurality of second semiconductor devices of turn-off type with a voltage blocking capacity rating of a second, lower level. A control arrangement of the converter is configured to switch a said valve into a conducting state starting from a forward biased blocking state of the valve by controlling the second semiconductor devices to be turned on and then the first semiconductor devices to be turned on with a delay, and at the end of the conducting state to turn off the first semiconductor device in advance of turning the second semiconductor devices off.
Abstract:
A device for converting a DC voltage into an AC voltage and vice versa comprises a control system to control the voltage conversion and at least one phase leg (1) with a first (Uvp1) voltage source connected in series between a first DC terminal (4) and a first AC terminal (6) and with a second (Uvn1) voltage source connected in series between the first AC terminal (6) and a second DC terminal (5). Each of the voltage sources comprises at least a first and a second submodule (15) in series-connection, where each submodule (15) comprises at least two power electronic switches (16) connected in parallel with at least one capacitor (17). The control system comprises a central control unit (19) and at least two subunits (20), where the central control unit (19) transmits to each subunit (20) a reference AC voltage (ua_ref) and a switching carrier signal (s_sw) and where each subunit (20) controls the switching of the power electronic switches (16) of one of the submodules (15) according to a PWM pattern so that each time the switching carrier signal (s_sw) crosses the reference AC voltage (ua_ref) either the voltage across the capacitor (17) or a zero voltage are applied to output terminals (26, 27) of the corresponding submodule (15).