Granted Patent B2

US 12,726,015 · App. 18/705,946 · Granted Sep 1, 2026

Inventors: Jimmy Öhman (Ludvika, SE); Ying Jiang Häfner (Ludvika, SE); Johan Österberg (Dalarna, SE); Michael Jons (Avesta, SE)

Assignee: HITACHI ENERGY LTD

H02H7/122H02J3/36

Abstract

Claims (29)

1 . A method for handling a fault in a High Voltage Direct Current, HVDC, converter comprising:

a plurality of converter valves, wherein each converter valve comprises a plurality of cells electrically connected in series, wherein each cell of the plurality of cells comprises an energy storage and a switch arrangement, and wherein the plurality of cells are operable to convert High Voltage Alternating Current, HVAC, to HVDC or HVDC to HVAC;

wherein each cell of the plurality of cells is configured to be operated in an active mode, in an inactive mode and a mechanical bypass mode;

the method comprising:

operating the switch arrangement of each of the cells operating in the active mode so as to convert High Voltage Alternating Current, HVAC, to HVDC or HVDC to HVAC, while

arranging the switch arrangement of each of the cells operating in the inactive mode to bypass the energy storage of the cell,

in response to an error indication for a cell operating in the active mode, switching the cell from operating in the active mode to operate in the inactive mode,

in response to a recovery indication for the cell operating in the inactive mode, switching the cell from operating in the inactive mode to operate in the active mode;

in response to a fault indication for a cell of the plurality cells, switching the cell to operating in the mechanical bypass mode in which a mechanical bypass switch of the cell is arranged to permanently bypass the energy storage and the switch arrangement of the cell;

determining a number of cells of a converter valve of the plurality of converter valves which are being operated in the inactive mode and a number of cells which are being operated in the mechanical bypass mode, and

in response to a predetermined number of cells of a converter valve of the plurality of converter valves being operated in the inactive mode or the mechanical bypass mode, tripping the converter valve.

2 . A High Voltage Direct Current, HVDC, converter comprising:

a plurality of converter valves, wherein each converter valve comprises a plurality of cells electrically connected in series, and wherein each cell of the plurality of cells comprises an energy storage and a switch arrangement, wherein the plurality of cells are operable to convert High Voltage Alternating Current, HVAC, to HVDC or HVDC to HVAC, wherein each cell of the plurality of cells further comprises a mechanical bypass switch configured for bypassing the energy storage and the switch arrangement of the cell, and;

a control system operably connected to the switch arrangements of the plurality of cells and configured to operate each cell of the plurality of cells in an active mode and in an inactive mode, and

wherein the control system is operably connected to the mechanical bypass switches and configured to operate each cell in a mechanical bypass mode in which the mechanical bypass switch of the cell is arranged to permanently bypass the energy storage and the switch arrangement of the cell;

wherein the control system is further configured to:

operate the switch arrangement of each of the cells operating in the active mode so as to contribute to converting High Voltage Alternating Current, HVAC, to HVDC or HVDC to HVAC while the switch arrangement of each of the cells operating in the inactive mode is arranged to bypass the electrical energy storage of the cell,

determine an error indication for a cell operating in the active mode and switch the cell from operating in the active mode to operate in the inactive mode in response to the error indication,

determine a recovery indication for the cell operating in the inactive mode,

switch the cell from operating in the inactive mode to operate in the active mode in response to the recovery indication,

determine a fault indication for a cell of the plurality of cells and switch the cell to operate in the mechanical bypass mode in response to the fault indication,

determine a number of cells of a converter valve of the plurality of converter valves which are being operated in the inactive mode and a number of cells which are being operated in the mechanical bypass mode, and

trip a converter valve of the plurality of converter valves when a predetermined number of cells of the plurality of cells of the converter valve are operated in the inactive mode or the mechanical bypass mode.

3 . An HVDC converter according to claim 2 , wherein the control system comprises a plurality of cell controllers, wherein each cell controller is operably connected to a switch arrangement of a respective cell for switching the cell between the active mode and the inactive mode.

4 . An HVDC converter according to claim 3 , wherein the control system further comprises a main controller operably connected to the plurality of cell controllers and configured to generate switching commands for the plurality of cell controllers, thereby converting High Voltage Alternating Current, HVAC, to HVDC or HVDC to HVAC.

5 . An HVDC converter according to claim 4 , wherein a cell controller of the plurality of cell controllers is further configured send a status update, indicating a cell switching between the active mode and the inactive mode, to the main controller for modifying the switching commands.

6 . An HVDC converter according to claim 2 , wherein each cell controller is operably connected to the switch arrangement of a respective cell via gate units of the respective cell,

wherein the gate units are communicatively coupled to the cell controller, and

wherein the control system is further configured to determine the error indication based on a monitored communication between a gate unit of the gate units and the cell controller which is communicatively coupled to said gate unit.

Assignments (3)

Continuity (1)

References Cited (9)