Abstract:
The present invention relates to an HVDC switchyard arranged to interconnect a first part of a DC grid with a second part of the DC grid. By means of the invention, a first part of the DC grid is connected to the busbars of the HVDC switchyard via a fast DC breaker, while further part(s) of the DC grid are connected to the busbars of the HVDC switchyard by means of switchyard DC breakers of lower breaking speed. By use of the inventive HVDC switchyard arrangement, the cost for the HVDC switchyard can be considerably reduced, while adequate protection can be provided. In one embodiment, the fast DC breaker is an HVDC station DC breaker forming part of an HVDC station. In another embodiment, the fast DC breaker is a switchyard DC breaker.
Abstract:
The present invention relates to an HVDC converter station for interconnection of a DC transmission line and an AC system of at least one AC phase. The HVDC converter station comprises a VSC converter and a DC breaker connected in series between the VSC converter and the DC transmission line. The HVDC converter station comprises a protection system configured to monitor the temperature of a reverse-conducting component of the reverse-conducting switch arrangement, and trigger the opening of the DC breaker if the temperature of the reverse-conducting component exceeds a temperature threshold.
Abstract:
An apparatus (302) for controlling the electric power transmission in a high voltage direct current, HVDC, power transmission system comprising at least one HVDC transmission line (102, 104, 106, 108, 110, 112, 114) for carrying direct current, wherein the apparatus (302) comprises a DC-to-DC converter (304) and a second converter (306) for converting alternating current to direct current and/or direct current to alternating current, the DC-to-DC converter having two DC sides for output and/or input of direct current, the second converter having an AC side (308) for output and/or input of alternating current and a DC side (310) for output and/or input of direct current. The DC-to-DC converter is connectable to the HVDC transmission line (102), and the second converter is connected via its DC side to the DC-to-DC converter. The second converter is connectable via its AC side to an AC source (314), and the apparatus is adapted to control the direct current of the HVDC transmission line by introducing a DC voltage in series with the HVDC transmission line. A HVDC power transmission system comprising the above-mentioned apparatus (302).
Abstract:
An arrangement for exchanging power, in shunt connection, with a three-phase electric power network (2) comprises on one hand for each said phase a reactive impedance element (31, 41, 51) and a Voltage Source Converter (32, 42, 52) connected in series with said element, and on the other a control unit (25) configured to control semiconductor devices of turn-off type of said converter for generating a voltage with a fundamental frequency being equal to the fundamental frequency of the voltage of the respective said phase and by that control a flow of reactive power between said arrangement and the respective phase of said electric power network. Each Voltage Sou rce Converter comprises a series connection of switching cells in the form of so-called H-bridges comprisi ng two switch ing elements connected in parallel and each having at least two semiconductor assemblies connected in series. Each switching cell further comprises at least one energy storing capacitor connected in parallel with said switching elements.
Abstract:
An arrangement to determine a cell capacitor voltage value (U dc ) of a cell (10") of a multi-cell power converter comprises the cell (10") and a control unit (28). The cell (10") itself comprises four power electronic valves (1-4) interconnected as a full-bridge converter having a first and a second phase leg, where each phase leg comprises a series-connection of two (1, 3; 2, 4) of the four power electronic valves and where the connection point (6; 7) between the two power electronic valves of each phase leg is externally connectable, a cell capacitor (5) being connected in parallel to the first and the second phase legs, and four gate units (16-19), each being connected to a corresponding one of the power electronic valves (1-4) as well as to the control unit (28). Each of the four gate units (16-19) comprises a voltage measurement unit (24-27) adapted to take a continuous voltage measurement across the corresponding power electronic valve, and each of the four gate units (16-19) is adapted to transmit its continuous voltage measurement. The control unit (28) is adapted to receive from each of the four gate units (16-19) its continuous voltage measurement and to determine the cell capacitor voltage value (U dc ) based on at least one of these voltage measurements.
Abstract:
It is presented a high voltage DC/DC converter for converting between a first DC connection and a second DC connection. The high voltage DC/DC converter comprises: a first set of DC terminals; a second set of DC terminals); a multiphase transformer device comprising a plurality of primary windings and a corresponding plurality of secondary windings; a first converter arranged to convert DC to AC, comprising a plurality of phase legs serially connected between the first set of DC terminals, wherein each phase leg is connected to an AC connection of a respective primary winding; and a second converter arranged to convert AC from the secondary windings to DC on the second set of DC terminals.
Abstract:
It is presented a method of controlling a magnitude of an electrical parameter in a power system by means of a high voltage electron tube. The method comprises the steps of measuring (S1) the magnitude of the electrical parameter; generating (S2) a control signal based on the magnitude of the electrical parameter and on a reference magnitude of the electrical parameter;and switching (S3) the high voltage electron tube by means of the control signal such that the reference magnitude of the electrical parameter is essentially obtained. It is also presented a control arrangement and a power system.
Abstract:
The invention concerns an arrangement (23) for transmitting power between a DC power line (12) and an AC power line (22A, 22B, 22C) carrying a voltage having a number of phases. The arrangement comprises a number of transformers (20A, 20B, 20C), one for each phase and a number of power transfer modules, one for each phase, connected in series between the DC power line and ground, where each module comprises a first branch including series connected converter cells (CA1, CA2, CB1, CB2, CC1, CC2 ) and a second branch comprising series connected switching elements (SW1A, SW2A, SW1B, SW2B, SW3A, SW3B). The primary winding of a transformer (20A, 20B, 20C) is connected to a corresponding AC phase conductor (22A, 22B, 22C) of the AC power line and the secondary winding is connected between a midpoint of the first branch and a midpoint of the second branch of a corresponding power transfer module.
Abstract:
Voltage source converter based on a chain-link cell topology, said converter comprising one or more phases (L1, L2, L3), each of said phases comprising one or more series- connected chain- link cell modules connected to each other, an output voltage of said voltage source converter is controlled by control signals applied to said cell modules. In case of failure of a chain- link cell module that module is controlled, by said control signals, such that zero output voltage is provided at its output voltage AC terminal.