Electrical switchgear with synchronous control system and actuator

• US 6,291,911 B1
• Filed: 06/25/1998
• Issued: 09/18/2001
• Est. Priority Date: 05/15/1995
• Status: Expired due to Term

• Current Assignee: Mcgraw-Edison Company (Eaton Corporation PLC.)
• Original Assignee: Cooper Industries, Inc. (Eaton Corporation PLC.)
• Inventors: Dunk, Michael Peter, Baranowski, John Francis
• Primary Examiner(s): FLEMING, FRITZ M
• Application Number:
  US09/104,377
• Time in Patent Office: 1,181 Days
• Field of Search: 307/137, 361/152-156, 361/160
• US Class Current: 307/137
• CPC Class Codes: H01F 2007/1894 minimizing impact energy on closure of magnetic circuit
• CPC Class Codes: H01H 11/0062 Testing or measuring non-electrical properties of switches, e.g. contact velocity monitoring contacts H01H1/0015; monitoring gas density H01H33/563; monitoring vacuum H01H33/668; calibrating H01H69/01; adjusting H01H71/74; testing of electrical properties G01R31/333
• CPC Class Codes: H01H 2003/268 using a linear motor
• CPC Class Codes: H01H 2009/566 with self learning, e.g. measured delay is used in later actuations
• CPC Class Codes: H01H 33/593 for ensuring operation of the switch at a predetermined point of the ac cycle for multipolar switches H01H9/563
• CPC Class Codes: H01H 33/666 Operating arrangements
• CPC Class Codes: H01H 47/325 by switching regulator

Abstract

In a power distribution system, synchronizing switchgear operations with an AC voltage or current waveform can be accomplished more precisely with a closed-loop feedback, microprocessor-based motion control design. By employing a closed-loop feedback, microprocessor-based design, switchgear contact position and velocity can be monitored and optimized in real time during a switching operation, thereby assuring a more accurate switching operation. Moreover, the closed-loop feedback design intrinsically compensates for the effects of such things as ambient temperature, AC waveform fluctuations, and changes in the physical condition of the switchgear. The closed-loop position feedback design is also capable of optimizing various transfer function parameters associated with the closed-loop feedback process, both during and subsequent to a switching operation, to further assure that switching operations are more accurately synchronized with the AC voltage or current waveforms.

Claims

1. A closed-loop feedback control system for electrical switchgear comprising:

a microprocessor;

a current generation means, operatively coupled to said microprocessor, for providing a driving current required to regulate an actuator for moving at least one of two switchgear contacts in the electrical switchgear; and

a position feedback means, operatively coupled to the at least one of two contacts, for repeatedly sampling position information of the at least one of two contacts and providing contact position information to the microprocessor,

wherein said microprocessor comprises means for controlling said current generation means in real-time, during a switching operation, as a function of an initial contact position and a present contact position, as provided by said position feedback means, such that the at least one contact transitions from the initial contact position to a final contact position in accordance with a pre-defined motion profile so as to provide AC waveform synchronized switching.

2. The closed-loop feedback control system of claim 1, wherein said means for controlling said current generation means comprises:

means for comparing switching operation performance data with the predefined motion profile during the switching operation; and

means for modifying the motion profile of the at least one contact during the switching operation by adjusting a transfer function associated with the closed-loop feedback control system based on the comparison of the switching operation performance data and the pre-defined motion profile.

3. The closed-loop feedback control system of claim 1, wherein said microprocessor further comprises:

means for saving past switching operation performance data from one or more prior switching operations;

means for comparing the past switching operation performance data with a desired performance profile; and

means for modifying the pre-defined motion profile by adjusting a transfer function associated with the closed-loop feedback control system, based on the comparison of the past switching operation performance data and the desired performance profile.

4. The closed-loop feedback control system of claim 1, wherein said means for controlling said current generation means comprises:

means for initiating the switching operation as a function of timing information associated with the AC waveform.

5. The closed-loop feedback control system of claim 4, wherein said means for controlling said current generation means further comprises:

means for saving past switching operation performance data from one or more prior switching operations; and

means for adjusting said switching operation initiation means as a function of the past switching operation performance data.

6. The closed-loop feedback control system of claim 5, wherein the past switching operation performance data includes a measure of AC waveform synchronization.

7. The closed-loop feedback control system of claim 4, wherein the timing information includes one or more pulses, each being generated concurrent to and as a result of a corresponding zero crossover point along the AC waveform, and wherein a time period between consecutive pulses corresponds to a half-cycle of the AC waveform.

8. The closed-loop feedback control system of claim 7, wherein said means for controlling the current generation means further comprises:

means for generating zero crossover point interrupt signals concurrent to and as a result of each of the one or more pulses;

means for generating a pre-defined number of timing interval interrupt signals during the period between each zero crossover point interrupt signal, wherein said means for initiating the switching operation is launched concurrent to a pre-defined one of the timed interval interrupt signals.

9. The closed-loop feedback control system of claim 4, wherein the timing information includes a timing pulse generated concurrent to and as a result of a zero-voltage differential across the two switchgear contacts.

10. The closed-loop feedback control system of claim 1, wherein said position feedback means comprises:

means for providing the initial contact position for said current generation control means based on a total distance traveled by the at least one contact during a previous switching operation.

11. The closed-loop feedback control system of claim 1, wherein the actuator utilized for moving the at least one of two switchgear contacts is associated with a voice coil.

12. The closed-loop feedback control system of claim 1, wherein the actuator utilized for moving the at least one of two switchgear contacts is associated with a linear motor.

13. The closed-loop feedback control system of claim 1, wherein the actuator utilized for moving the at least one of two switchgear contacts is associated with a hydraulic unit.

14. The closed-loop feedback control system of claim 1, wherein the pre-defined motion profile comprises a profile of velocities at which the at least one contact should travel during a transition.

15. The closed-loop feedback control system of claim 1, wherein said microprocessor provides AC waveform synchronized switching by initiating the at least one contact to close or open when an AC value across the contacts is substantially zero.

16. The closed-loop feedback control system of claim 15, wherein the AC value is a current value.

17. The closed-loop feedback control system of claim 15, wherein the AC value is a voltage value.

18. The closed-loop feedback control system of claim 1, wherein position information of a contact comprises a position of the contact.

19. A capacitor switch comprising:

a current interrupter containing at least one moveable contact;

an actuator coupled to the at least one moveable contact;

a closed-loop feedback, motion control circuit comprising;

a microprocessor,

a pulse-width modulation (PWM) circuit, operatively coupled to said microprocessor, wherein said PWM circuit produces driving current for said actuator which is required to drive the at least one moveable contact from an initial contact position to a final contact position during a switching operation,

a position sensor optically coupled to the at least one contact to repeatedly sample position data of the at least one moveable contact,

a decoder, wherein said decoder receives and decodes the contact position data from said position sensor and forwards the decoded contact position data to said microprocessor,

wherein said microprocessor includes closed-loop feedback means for controlling contact position and velocity in real-time, during the switching operation, based on the initial contact position, a present contact position feedback signal and a present contact velocity feedback signal, such that the switching operation is synchronized with an AC voltage waveform across the capacitor switch.

20. The capacitor switch of claim 19, wherein said PWM circuit comprises:

a digital-to-analog converter; and

a power amplifier.

21. The capacitor switch of claim 19, wherein said position sensor is an optical, quadrature encoder.

22. The capacitor switch of claim 19, wherein said closed-loop feedback means for controlling contact position and velocity comprises:

means for deriving the contact velocity feedback signal from the contact position feedback signal;

means for comparing the contact velocity feedback signal with a pre-defined motion profile; and

means for adjusting the current produced by said PWM circuit as a function of the comparison between the contact velocity feedback signal and the pre-defined motion profile.

23. The capacitor switch of claim 22, wherein the pre-defined motion profile comprises a profile of velocities at which the at least one contact should travel over a duration of a switching operation.

24. The capacitor switch of claim 19, wherein said microprocessor further includes:

means for saving velocity feedback data associated with one or more prior switching operations;

means for comparing the velocity feedback data from the one or more prior switching operations with a pre-defined motion profile; and

means for modifying the pre-defined motion profile by adjusting a transfer function associated with said closed-loop feedback motion control circuit based on the comparison between the velocity feedback data from the one or more prior switching operations and the pre-defined motion profile.

25. The capacitor switch of claim 19, further comprising:

an AC voltage waveform analysis circuit; and

a capacitor switch control interface.

26. The capacitor switch of claim 25, wherein said microprocessor further comprises:

means for receiving timing information from said AC voltage waveform analysis circuit;

means for receiving a switching operation execute command from said capacitor switch control interface; and

means for initiating the switching operation as a function of the timing information and the switching operation execute command.

27. The capacitor switch of claim 26, wherein said microprocessor further comprises:

means for saving switching operation performance data from one or more prior switching operations; and

means for adjusting said switching operation initiation means based on the switching operation performance data from the one or more prior switching operations, wherein the switching operation performance data from the one or more prior switching operations includes a measure of AC voltage waveform synchronization.

28. The capacitor switch of claim 26, wherein the timing information includes a plurality of timing pulses, and wherein each timing pulse is generated by the AC voltage waveform analysis circuit concurrent to and as a function of a zero-voltage crossover point along the AC voltage waveform.

29. The capacitor switch of claim 28, wherein the timing information includes zero-voltage crossover interrupt signals, each being generated by said microprocessor concurrent to and as a result of a corresponding timing pulse.

30. The capacitor switch of claim 29, wherein the timing information includes a number of timed interval interrupt signals generated at equally-spaced intervals by the microprocessor during the period between consecutive zero-voltage interrupt signals.

31. The capacitor switch of claim 26, wherein the timing information includes a timing pulse associated with a zero-voltage differential across the capacitor switch contacts.

32. The capacitor switch of claim 19, wherein said actuator is associated with a voice coil.

33. The capacitor switch of claim 19, wherein said actuator is associated with a linear motor.

34. The capacitor switch of claim 19, wherein said actuator is associated with a hydraulic unit.

35. The capacitor switch of claim 19, wherein said microprocessor provides AC waveform synchronized switching by initiating the at least one contact to close or open when an AC voltage value across the contacts is substantially zero.

36. The capacitor switch of claim 19, wherein the decoder continuously receives and decodes the position data from the position sensor.

37. A closed-loop feedback method for controlling at least one contact in an electrical switchgear during a switching operation, said method comprising the steps of:

generating a driving current required to move the at least one contact;

generating contact position feedback in real-time, during the switching operation, by repeatedly receiving samples of a position of the at least one contact; and

controlling the generation of driving current required to regulate the movement of the at least one contact in real-time, during the switching operation, as a function of an initial contact position and the real-time contact position feedback data, such that the at least one contact transitions from the initial contact position to a final contact position in accordance with a pre-defined motion profile so as to provide AC voltage or current waveform synchronized switching.

38. The method of claim 37, wherein said step of controlling the generation of driving current required to regulate the movement of the at least one contact in real-time, during the switching operation comprises the steps of:

deriving real-time contact velocity feedback data from the real-time contact position feedback data;

comparing the real-time contact velocity feedback data with a pre-defined motion profile; and

adjusting the driving current required to regulate the movement of the at least one contact as a function of the comparison between the contact velocity feedback data and the pre-defined motion profile.

39. The method of claim 37 further comprising the steps of:

saving the contact velocity feedback data associated with one or more prior switching operations;

comparing the contact velocity feedback data from the one or more prior switching operations with a pre-defined motion profile; and

modifying the pre-defined motion profile based on the comparison between the velocity feedback data from the one or more prior switching operations and the pre-defined motion profile.

40. The method of claim 37 further comprising the step of:

initiating the switching operation as a function of timing information and a switching operation execute command, wherein the timing information is associated with the AC voltage or current waveform.

41. The method of claim 40 further comprising the steps of:

saving switching operation performance data from one or more prior switching operations; and

adjusting switching operation initiation based on the switching operation performance data from the one or more prior switching operations, wherein the switching operation performance data from the one or more prior switching operations includes a measure of AC voltage or current waveform synchronization.

42. The method of claim 40, wherein the timing information includes timing pulses, each associated with a zero-voltage or zero-current crossover point along the AC voltage or current waveform, respectively.

43. The method of claim 42, wherein the timing information includes zero-voltage or zero-current crossover interrupt signals, each being generated concurrent to and as a result of a corresponding timing pulse.

44. The method of claim 43, wherein the timing information includes a number of timed interval interrupt signals, each being associated with one of a plurality of equally-spaced timing intervals between adjacent zero-voltage or zero-current crossover interrupt signals.

45. The method of claim 40, wherein the timing information includes a timing signal associated with a zero-voltage differential across the switchgear contacts.

46. The method of claim 37, wherein the pre-defined motion profile comprises a profile of velocities at which the at least one contact should travel over a duration of a switching operation.

47. The method of claim 37, wherein providing AC voltage waveform synchronized switching comprises initiating the at least one contact to close or open when an AC voltage value across the contacts is substantially zero.

48. The method of claim 37, wherein providing AC current waveform synchronized switching comprises initiating the at least one contact to close or open when an AC current value across the contacts is substantially zero.