Valve position control

Patent metadata

Field	Value
Publication number	US-11814964-B2
Application number	US-202017092477-A
Country	US
Kind code	B2
Filing date	Nov 9, 2020
Priority date	May 9, 2018
Publication date	Nov 14, 2023
Grant date	Nov 14, 2023

Abstract

A control system is provided for a turbine valve. The turbine valve has a first coil and a second coil to control or sense movement of a mechanical valve positioner. Two valve positioners are provided with each valve positioner having two drive circuits to drive the first and second coils. Switches are provided such that only one drive circuit is connected to each coil at a time. The control system may also include a hydraulic pilot valve section and a main hydraulic valve section. Feedbacks are used to determine a pilot valve error and a main valve error which are combined to determine a turbine valve error. The turbine valve error is repeatedly determined to minimize the error.

First claim

The invention claimed is:

1. A system for redundant valve positioning, comprising:
a mechanical valve positioner connected to a turbine valve to open and close the turbine valve, the mechanical valve positioner comprising a first coil and a second coil to control or sense movement of the mechanical valve positioner;
a first valve positioner comprising a first drive circuit and a second drive circuit, the first drive circuit comprising a first driver and a first switch, and the second drive circuit comprising a second driver and a second switch, the first drive circuit being in communication the first coil and the second drive circuit being in communication with the second coil;
a second valve positioner comprising a third drive circuit and a fourth drive circuit, the third drive circuit comprising a third driver and a third switch, and the fourth drive circuit comprising a fourth driver and a fourth switch, the third drive circuit being in communication the first coil and the fourth drive circuit being in communication with the second coil;
wherein only one of the first switch and the third switch is closed at a time, the first driver and the third driver thereby being alternately connected to the first coil at different times such that the first driver and the third driver do not drive the first coil at a same time; and
wherein only one of the second switch and the fourth switch is closed at a time, the second driver and the fourth driver thereby being alternately connected to the second coil at different times such that the second driver and the fourth driver do not drive the second coil at a same time.

2. The system for redundant valve positioning according to claim 1 , wherein the first coil and the second coil are redundant coils.

3. The system for redundant valve positioning according to claim 1 , wherein the first coil and the second coil are redundant position sensing coils.

4. The system for redundant valve positioning according to claim 3 , wherein the first coil and the second coil are each a primary coil in a respective first linear variable differential transformer (LVDT) and a second respective linear variable differential transformer (LVDT), the first LVDT and the second LVDT being redundant LVDTs.

5. The system for redundant valve positioning according to claim 4 , wherein the first LVDT comprises a first secondary coil outputting a first position signal and the second LVDT comprises a second secondary coil outputting a second position signal, the first secondary coil and the second secondary coil both being in communication with the first valve positioner and the second valve positioner such that the first valve positioner and the second valve positioner both receive the first position signal and the second valve position signal.

6. The system for redundant valve positioning according to claim 5 , wherein the communications between the first secondary coil, the second secondary coil, the first valve positioner and the second valve positioner are non-switched such that the first valve positioner and the second valve positioner both receive the first position signal and the second position signal at a same time.

7. The system for redundant valve positioning according to claim 1 , wherein the first coil and the second coil are redundant servo positioning coils.

8. The system for redundant valve positioning according to claim 1 , wherein the first valve positioner and the second valve positioner share a termination unit which interfaces with the first coil and the second coil.

9. The system for redundant valve positioning according to claim 8 , wherein a first field wire connects the first coil to the termination unit and a second field wire connects the second coil to the termination unit, the first drive circuit and the third drive circuit both communicating with the first coil through the first field wire and the second drive circuit and the fourth drive circuit both communicating with the second coil through the second field wire.

10. The system for redundant valve positioning according to claim 1 , wherein the first valve positioner and the second valve positioner are separate hardware modules.

11. The system for redundant valve positioning according to claim 10 , wherein the first valve positioner comprises a first circuit board and the second valve positioner comprises a second circuit board, the first drive circuit and the second drive circuit being incorporated into the first circuit board, and the third drive circuit and the fourth drive circuit being incorporated into the second circuit board.

12. The system for redundant valve positioning according to claim 11 , further comprising a base with a first communications connector and a second communications connector, wherein the first valve positioner is connected to the first communications connector and the second valve positioner is connected to the second communications connector, the first valve positioner and the second valve positioner communicating directly with each other through the base to control the first switch, the second switch, the third switch and the fourth switch.

13. The system for redundant valve positioning according to claim 12 , wherein the base further comprises a third communications connector, the first valve positioner and the second valve positioner being in communication with a controller through the third communications connector.

14. The system for redundant valve positioning according to claim 1 , wherein the first valve positioner is a primary module and the second valve positioner is a backup module, the first switch and the second switch being closed and the third switch and the fourth switch being open during normal operation, and upon a failure of the first valve positioner at least the first switch is opened and the third switch is closed to transfer control or sensing from the primary module to the backup module.

15. The system for redundant valve positioning according to claim 1 , wherein the first switch, the second switch, the third switch and the fourth switch are each a solid state relay.

16. The system for redundant valve positioning according to claim 1 , wherein:
the mechanical valve positioner further comprises a third coil and a fourth coil, the first coil and the second coil being redundant position sensing coils, and the third coil and the fourth coil being redundant servo positioning coils;
the first valve positioner further comprising a fifth drive circuit and a sixth drive circuit, the fifth drive circuit comprising a fifth driver and a fifth switch, and the sixth drive circuit comprising a sixth driver and a sixth switch, the fifth drive circuit being in communication the third coil and the sixth drive circuit being in communication with the fourth coil;
the second valve positioner further comprising a seventh drive circuit and an eighth drive circuit, the seventh drive circuit comprising a seventh driver and a seventh switch, and the eighth drive circuit comprising an eighth driver and an eighth switch, the seventh drive circuit being in communication the third coil and the eighth drive circuit being in communication with the fourth coil;
wherein only one of the fifth switch and the seventh switch is closed at a time, the fifth driver and the seventh driver thereby being alternately connected to the third coil at different times such that the fifth driver and the seventh driver do not drive the third coil at a same time; and
wherein only one of the sixth switch and the eighth switch is closed at a time, the sixth driver and the eighth driver thereby being alternately connected t

Assignees

• Abb Schweiz Ag

Inventors

• Lopez Camilo
• Foltz Mark
• Miller Steve
• Dowdell Kevin
• Wieland Mark
• Majors Alan

Classifications

• F01C20/28 Primary

  Safety arrangements; Monitoring · CPC title

• F01D17/06

  responsive to speed · CPC title

• F01D17/145 Primary

  by means of valves, e.g. for steam turbines (valves in general F16K) · CPC title

• F01D17/26

  fluid, e.g. hydraulic · CPC title

• F01D21/02

  Shutting-down responsive to overspeed · CPC title