Office Action 3: Notice of Allowance (2025-02-20)

CLAIMS:
AMENDMENTS TO THE CLAIMS

This listing of claims will replace all prior versions and listings of claims in the subject application.

1-8. (Cancelled)27

9\. (Currently Amended) A converter station, for a bipole power transmission scheme, comprising:
a first voltage source converter having a first terminal for connection to a first transmission conduit, a second terminal for connection to a return conduit, and at least one converter limb extending between the first and second terminals, the or each converter limb including first and second limb portions separated by a corresponding first AC terminal for connection to a respective phase of a first AC network, the or each first limb portion including a first chain-link converter extending between the associated first AC terminal and the first terminal, the or each second limb portion including a second chain-link converter extending between the associated first AC terminal and the second terminal, and each chain-link converter including a plurality of series connected chain-link modules each having a plurality of switching elements connected in parallel with an energy storage device whereby each chain-link converter is controllable to provide a stepped variable voltage source; and
a second voltage source converter having a third terminal for connection to a second transmission conduit, a fourth terminal for connection to the return conduit, and at least one converter limb extending between the third and fourth terminals, the or each converter limb including third and fourth limb portions separated by a corresponding second AC terminal for connection to a respective phase of a second AC network, the or each third limb portion including a third chain-link converter extending between the associated second AC terminal and the third terminal, the or each fourth limb portion including a fourth chain-link converter extending between the associated second AC terminal and the fourth terminal, and each chain-link converter including a plurality of series connected chain-link modules each having a plurality of switching elements connected in parallel with an energy storage device whereby each chain-link converter is controllable to provide a stepped variable voltage source,
wherein the second terminal and the fourth terminal are electrically connected to one another,

wherein each of the second and third chain-link converters consists of a first number of series-connected chain-link modules, and each of the first and fourth chain-link converters consists of a second number of series-connected chain-link modules, the second number being greater than the first number.

10\. (Currently Amended) A converter station according to claim 9, wherein each of the second and third chain-link converters consists of the same first number of series- connected chain-link modules.

11\. (Currently Amended) A converter station according to claim 9, wherein each of the first and fourth chain-link converters consists of the same second number of series- connected chain-link modules.

12\. (Previously Presented) A converter station according to claim 9, wherein each chain-link module has the same topology.

13\. (Previously Presented) A converter station according to claim 12, wherein each chain-link module includes a first pair of switching elements connected in parallel with the energy storage device in a half-bridge arrangement to define a 2-quadrant unipolar module.

14\. (Previously Presented) A converter station according to claim 9, wherein at least one of the first and second voltage source converters includes a corresponding voltage source converter controller programmed to control the stepped variable voltage source provided by the said corresponding voltage source converter, and when doing so to balance the total energy stored by the energy storage devices in one limb portion of the said voltage source converter with the total energy stored by the energy storage devices in the other corresponding limb portion of the voltage source converter.

15\. (Previously Presented) A converter station according to claim 14, wherein the at least one voltage source converter controller is programmed to cause the chain-link modules in the limb portion having the higher second number of chain-link modules to store a proportionally

lower individual average amount of energy than the individual average amount of energy stored by each of the chain-link modules in the other corresponding limb portion.

16\. (Currently Amended) A method of operating a converter station comprising:
a first voltage source converter having a first terminal connected to a first transmission conduit, a second terminal connected to a return conduit, and at least one converter limb extending between the first and second terminals, the or each converter limb including first and second limb portions separated by a corresponding first AC terminal connected to a respective phase of a first AC network, the or each first limb portion including a first chain-link converter extending between the associated first AC terminal and the first terminal, the or each second limb portion including a second chain-link converter extending between the associated first AC terminal and the second terminal, and each chain-link converter including a plurality of series connected chain-link modules each having a plurality of switching elements connected in parallel with an energy storage device whereby each chain-link converter is controllable to provide a stepped variable voltage source; and
a second voltage source converter having a third terminal connected to a second transmission conduit, a fourth terminal for connection to the return conduit, and at least one converter limb extending between the third and fourth terminals, the or each converter limb including third and fourth limb portions separated by a corresponding second AC terminal connected to a respective phase of a second AC network, the third limb portion including a third chain-link converter extending between the associated second AC terminal and the third terminal, the fourth limb portion including a fourth chain-link converter extending between the associated second AC terminal and the fourth terminal, and each chain-link converter including a plurality of series connected chain-link modules each having a plurality of switching elements connected in parallel with an energy storage device whereby each chain-link converter is controllable to provide a stepped variable voltage source,

 wherein each of the second and third chain-link converters consists of a first number of series-connected chain-link modules; and
 each of the first and fourth chain-link converters consists of a second number of series-connected chain-link modules, the second number being greater than the first number.

OFFICE ACTION:
Drawings
The drawing amendments, as received on 31 January 2025, are acceptable.
Allowable Subject Matter
Claims 9-16 are allowed.
Independent claims 9 and 16 have been amended by Applicant substantially in accordance with the language previously suggested by the examiner. As such, the claims stand allowable for the same reasons as have already been explained on record—see the Final Rejection dated 27 November 2024.
Conclusion

APPLICANT REBUTTAL: AMENDMENT AND RESPONSE TO FINAL OFFICE ACTION

AMENDMENTS TO THE DRAWINGS
Replacement sheet is submitted herewith for FIG. 1. No new matter has been added.
Attachment: Replacement Sheet for FIG 1