REDUNDANT CURRENT VALVE CONTROL IN A HIGH VOLTAGE POWER TRANSMISSION SYSTEM

• US 20100157633A1
• Filed: 05/12/2008
• Published: 06/24/2010
• Est. Priority Date: 05/14/2007
• Status: Active Grant

• Current Assignee: Hitachi Energy Limited
• Original Assignee: ABB Technology AB (ABB Limited)
• Inventors: Nyberg, Krister, Björklund, Hans
• Granted Patent: US 8,305,782 B2
• Time in Patent Office: Days
• US Class Current: 363/74
• CPC Class Codes: H02J 3/36 Arrangements for transfer of electric power between ac networks via a high-tension dc link
• CPC Class Codes: H02M 1/08 Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
• CPC Class Codes: H02M 5/4505 having a rectifier with controlled elements
• CPC Class Codes: H02M 5/4585 having a rectifier with controlled elements
• CPC Class Codes: Y02E 60/60 Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

Abstract

A method and device for providing redundant control of a controllable current valve in a converter of a power transmission system. A first converter control unit sends a first valve control signal. A first active/standby indicator is associated with the first converter. A second converter control unit sends a second valve control signal. A second active/standby indicator is associated with the second converter control unit. The device also includes a valve control unit. An active/standby indicator indicates if a corresponding converter control unit is active or standby. Only one indicator indicates an active unit at a given point in time. The valve control unit receives the active/standby indicators and valve control signals, selects a valve control signal to be applied if the corresponding active/standby indicator indicates an active converter control unit and controls the current valve using the selected valve control signal.

Claims

1. A method for providing redundant control of at least one controllable current valve provided in a converter of a high voltage power transmission system, the method comprising:

sending a first valve control signal for said at least one controllable valve and an associated first active/standby indicator from a first converter control unit to a valve control unit,

sending a second valve control signal for said at least one controllable valve and an associated second active/standby indicator) from a second converter control unit to said valve control unit, wherein an active/standby indicator indicates if a corresponding converter control unit is an active or standby converter control unit and only one active/standby indicator indicates an active converter control unit at a given point in time,

receiving, with said valve control unit, said active/standby indicators and said first and second valve control signals,

selecting, with said valve control unit, a valve control signal to be used for controlling said current valve if the associated active/standby indicator indicates an active converter control unit, and

controlling said current valve using said selected valve control signal.

2. The method according to claim 1, wherein the selecting comprises:

determining if said first valve control signal is to be applied based on the first active/standby indicator, and

determining if said second valve control signal is to be applied based on the second active/standby indicator,

wherein the determinations are performed in parallel independently of each other.

3. The method according to claim 1, wherein the controlling comprises converting the valve control signal that is associated with an active/standby indicator indicating an active converter control unit to a valve driving signal, and applying said valve driving signal to said valve.

4. The method according to claim 1, further comprising:

returning, with the valve control unit, an acknowledgement of each received converter control signal to the corresponding converter control unit through returning said received valve control signal.

5. The method according to claim 1, further comprising:

supervising, with each converter control unit, a functionality and a handing over of each converter control unit, with the active converter control unit, control to the standby converter control unit in case faults are detected in the supervised functionality.

6. The method according to claim 5, wherein the handing over control is performed using handshaking.

7. The method according to claim 1, further comprising:

monitoring, with a system protection unit, at least one operating condition of the system, providing, by said system protection unit, a system safety measure in case the operating condition reaches a risk state and ordering, with the system protection unit, the active converter control unit to handover control to the standby converter control unit if the monitored operating condition is in proximity of the risk state.

8. The method according to claim 1, wherein the high voltage power transmission system is a DC power transmission system.

9. The method according to claim 1, wherein the high voltage power transmission system is operating at voltages around 800 kV.

10. A device for providing redundant control of at least one controllable current valve provided in a converter of a high voltage power transmission system, the device comprising:

a first converter control unit arranged to send a first valve control signal for said at least one controllable valve and an associated first active/standby indicator,

a second converter control unit arranged to send a second valve control signal for said at least one controllable valve and an associated second active/standby indicator, wherein an active/standby indicator indicates if a corresponding converter control unit is an active or standby converter control unit and only one active/standby indicator indicates an active converter control unit at a given point in time, and

a valve control unit arranged to

receive said active/standby indicators and said first and second valve control signals,

select a valve control signal to be applied for controlling said current valve if the corresponding active/standby indicator indicates an active converter control unit, and

control said current valve using said selected valve control signal.

11. The device according to claim 10, wherein the valve control unit comprises

a first valve control element arranged to receive said first valve control signal, receive said first active/standby indicator and determine if said first valve control signal is to be applied based on the first active/standby indicator, and

a second valve control element arranged to receive said second valve control signal, receive said second active/standby indicator and determine if said second valve control signal is to be applied based on the second active/standby indicator,

wherein the first and second valve control elements are arranged to perform said determinations in parallel independently of each other.

12. The device according to claim 11, wherein the valve control element which has received an active/standby indicator indicating an active converter control unit is further arranged to convert the corresponding valve control signal to a valve driving signal to be applied to said at least one controllable valve.

13. The device according to claim 11, wherein each valve control element is arranged to return an acknowledgement to the corresponding converter control unit through returning said received valve control signal.

14. The device according to claim 10, wherein each converter control unit is arranged to supervise its own functionality and the active converter control unit is further arranged to handover control to the standby converter control unit in case faults are detected in the supervised functionality.

15. The device according to claim 14, wherein the active converter control unit is arranged to handover control to the standby converter control unit through handshaking.

16. The device according to claim 10, further comprising:

a system protection unit arranged to monitor at least one operating condition of the system and to provide a system safety measure in case the operating condition reaches a risk state, wherein the system protection unit is further arranged to order the active converter control unit to handover control to the standby converter control unit if the monitored operating condition is in proximity of the risk state.