Power transmission networks

Patent metadata

Field	Value
Publication number	US-10778011-B2
Application number	US-201716348459-A
Country	US
Kind code	B2
Filing date	Oct 31, 2017
Priority date	Nov 9, 2016
Publication date	Sep 15, 2020
Grant date	Sep 15, 2020

Abstract

In the field of high voltage direct current (HVDC) power transmission there is provided a power converter assembly (10) comprising a line-commutated power converter (12) that is configured to transfer power from a DC network (14) to a corresponding receiving AC network (16). The power converter assembly (10) also includes a control unit which is operatively associated with the line-commutated power converter (12) and is programmed, in response to the receiving AC network (16) exhibiting a reduced AC voltage (Va, Vb, Vc), to cause a reduction in the operating DC voltage (VDC) of the line-commutated power converter (12) by the DC network (14).

First claim

The invention claimed is:

1. A power converter assembly, for use in a high voltage direct current (HVDC) power transmission network, comprising:
a line-commutated power converter configured to transfer power from a DC network to a corresponding receiving AC network; and
a control unit operatively associated with the line-commutated power converter, the control unit being programmed to:
identify a commutation failure in the line-commutated power converter; and
send, based on an identified commutation failure, an instruction to reduce the operating DC voltage (V DC ) of the line-commutated power converter.

2. The power converter assembly according to claim 1 wherein the control unit is programmed to cause a reduction in the operating DC voltage (V DC ) of the line-commutated converter which is proportional to the reduction in the AC voltage (V a , V b , V c ) in the corresponding receiving AC network.

3. The power converter assembly according to claim 1 wherein the instruction to reduce the operating DC voltage (V DC ) of the line-commutated power converter is based on at least one of:
a change in DC current (I DC ) provided to the line-commutated converter;
a change in AC current within the corresponding faulty receiving AC network; or
a change to the extinction angle (γ) order provided to each line-commutated switching element in the line-commutated converter.

4. The power converter assembly according to claim 1 wherein the control unit is programmed to establish a reduced DC voltage demand order (V DCO ) which tracks the AC voltage (V a , V b , V c ) in the corresponding receiving AC network.

5. The power converter assembly according to claim 4 wherein the control unit takes the form of a local control unit which directly controls the operating DC voltage (V DC ) of the line-commutated power converter according to the reduced DC voltage demand order (V DCO ).

6. The power converter assembly according to claim 5 wherein the local control unit is further programmed to dispatch the reduced DC voltage demand order (V DCO ) to:
(i) a higher level controller configured to coordinate and control the operation of one or more other power converters configured to provide a DC voltage (V DC ) to the line-commutated power converter; or
(ii) a local control unit of one or more other power converters configured to provide a DC voltage (V DC ) to the line-commutated power converter.

7. The power converter assembly according to claim 4 wherein the control unit takes the form of a higher level controller which indirectly controls the operating DC voltage (V DC ) of the line-commutated power converter according to the reduced DC voltage demand order (V DCO ) it establishes.

8. The power converter assembly according to claim 7 wherein the higher level controller is configured to coordinate and control the operation of one or more other power converters configured to provide a DC voltage (V DC ) to the line-commutated power converter.

9. The power converter assembly according to claim 1 wherein the control unit is configured to receive data indicative of the magnitude (E ll ) of the AC voltage (V a , V b , V c ) in the corresponding receiving AC network.

10. The power converter assembly according to claim 9 wherein the data includes one or more of:
an average AC voltage level; and
a peak voltage level.

11. The power converter assembly according to claim 9 wherein the corresponding receiving AC network is a multi-phase (a, b, c) network and the data includes:
a single multi-phase line to line voltage measurement; or
separate single phase line to line voltage measurements.

12. The power transmission network comprising a power converter assembly according to claim 1 and one or more other power converters configured to transfer power from a corresponding sending AC network to the line-commutated power converter of the power converter assembly via an interconnecting DC network.

13. The power transmission network according to claim 12 further including at least one further line-commutated power converter.

14. The power transmission network according to claim 13 wherein the at least one further line-commutated power converter is operatively associated with a control unit programmed, in response to the receiving AC network of the corresponding further line-commutated converter exhibiting a reduced AC voltage, to cause a reduction in the operating DC voltage of the corresponding line-commutated power converter.

15. A method comprising:
transferring, by a line-commutated power converter, power from a DC network to a corresponding receiving AC network;
identifying a commutation failure in a line-commutated power converter; and
sending, based on identifying the commutation failure, an instruction to reduce the operating DC voltage (V DC ) of the line-commutated power converter.

16. The method of claim 15 , further comprising:
causing, via the control unit, a reduction in the operating DC voltage (V DC ) of the line-commutated converter which is proportional to the reduction in the AC voltage (V a , V b , V c ) in the corresponding receiving AC network.

17. The method of claim 15 , wherein
based at least in part on one or more of the following when causing the reduction in the operating DC voltage (V DC ) of the line-commutated power converter:
a change in DC current (I DC ) provided to the line-commutated converter;
a change in AC current within the corresponding faulty receiving AC network; and
a change to the extinction angle (γ) order provided to each line-commutated switching element in the line-commutated converter.

18. The method of claim 15 , further comprising:
establishing, via the control unit, a reduced DC voltage demand order (V DCO ) which tracks the AC voltage (V a , V b , V c ) in the corresponding receiving AC network.

Assignees

• General Electric Technology Gmbh

Inventors

• Whitehouse Robert
• Barker Carl D
• Ghebreyesus Ghirmazion

Classifications

• H02J3/36 Primary

  Arrangements for transfer of electric power between AC networks via high-voltage DC [HVDC] links; Arrangements for transfer of electric power between generators and networks via HVDC links · CPC title

• Y02E60/60

  Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD] · CPC title