Intelligent pump system

• US 8,774,972 B2
• Filed: 05/14/2007
• Issued: 07/08/2014
• Est. Priority Date: 05/14/2007
• Status: Active Grant

• Current Assignee: Flowserve Management Company (Flowserve Corporation)
• Original Assignee: Flowserve Management Company (Flowserve Corporation)
• Inventors: Rusnak, Dennis M., Ballard, Jason, Turley, Roger S.
• Primary Examiner(s): Jarrett, Ryan
• Assistant Examiner(s): LOPEZ ALVAREZ, OLVIN
• Application Number:
  US11/748,126
• Publication Number:
  US 20080288115A1
• Time in Patent Office: 2,612 Days
• Field of Search: 700/282, 415/122.1, 417/4
• US Class Current: 700/282
• CPC Class Codes: F04D 15/0066 by changing the speed, e.g. of the driving engine

Abstract

The present invention is a controller specifically for pumps, making the benefits of variable frequency drive (VFD) technology more accessible to pump users. The present invention incorporates pump-specific system optimization software, an industrial grade drive, and a menu-driven user interface, offering protection, reliability, and ease of use not possible with other variable frequency drives.

Claims

1. A method of controlling operation of a centrifugal pump in a fluid pumping system having a variable frequency drive (VFD) powering an alternating current (AC) motor which turns said centrifugal pump, said method comprising:

internally monitoring automatically output current and voltage of the VFD to the AC motor without the need for an external sensor;

calculating automatically output power based on monitored values of said output current and voltage and not on torque or speed of the AC motor;

checking automatically whether said calculated output power is above a predetermined high power limit for a desired setpoint;

checking automatically whether said calculated output power is below a predetermined low power limit for said desired setpoint,

wherein said high and low power limits vary depending upon pump operating speed;

receiving feedback from an external process sensor,

wherein said feedback is indicative of said desired setpoint;

and initiating automatically a first predetermined response action if said calculated output power is either above said predetermined high power limit or below said predetermined low power limit;

wherein said high power limit is set to lowest of either power at the end of a performance curve of the pump, maximum rated motor power, or power rating of magnetic coupling of a magnetic drive pump or a canned motor pump, and wherein said low power limit is set for the highest of the performance curve of the pump or power required at minimum continuous recommended flow;

using a high power level delay which is a time period that the output power must exceed the high power limit before said predetermined response action is initiated;

monitoring an externally provided analog sensor signal;

and initiating automatically a second predetermined response action if in a signal threshold level mode said analog sensor signal crosses one or both preset levels in the same direction,

wherein each of said preset levels can initiate a separate response, or if in boundary mode, said analog sensor signal rising above a preset maximum value or drops below a preset minimum value, and in both modes, if after expiration of a time delay said analog sensor signal is still above one or both said preset levels if in a signal threshold level mode, or above or below said present maximum and minimum present values, respectively, if in boundary mode.

3. The method of claim 1 wherein said method further comprises automatically adjusting said high and low power limits using pump Affinity Law calculations for a current pump operating speed.

4. The method of claim 1 wherein said method further comprises automatically calculating said high and low power limits initially using said pump Affinity Law calculations and a predetermined pump speed, and automatically adjusting said high and low power limits using said pump Affinity Law calculations for a current pump operating speed detected by said external process sensor.

5. The method of claim 1 further comprising using a motor efficiency factor with said calculated output power to provide a better estimation of actual motor power to the pump.

6. The method of claim 1 further comprising using an automatic start time delay to allow the pump to attain normal operations during startup and to prevent fluctuations in said output power during the startup from triggering said first predetermined response action,

wherein said high and low power limits are disabled during the time period of said automatic start time delay.

7. The method of claim 1 further comprising using an automatic retry to attempt to re-establish normal operations after triggering said first predetermined response action and a preset retry time delay, wherein the number of retries of said automatic retry is adjustable.

8. The method of claim 1 further comprising using a low power level delay which is a time period that the output power must be below the low power limit before said first predetermined response action is initiated.

9. The method of claim 1 further comprising:

using an automatic retry to attempt to re-establish normal operations after triggering said first predetermined response action and a preset retry time delay, wherein the number of retries of said automatic retry is adjustable;

and aborting said automatic retry process if said number of retries is set to zero or number of tries is exhausted.

10. The method of claim 1 further comprising using said method to detect operating conditions that are harmful to at least one of the pump and the process, the operating condition selected from the group consisting of dry running, low flow, changes in pumped fluid characteristics, blocked lines, blocked filters, blocked heat exchangers, uncoupled pump, closed suction or discharge valves, overload conditions, excessive wear, or rubbing.

11. The method of claim 1 wherein said first predetermined response action is to activate a digital output relay to initiate other user defined actions.

12. The method of claim 1, wherein said first predetermined response action is to activate a digital output relay to initiate other user defined actions selected from a condition annunciation using an external signaling device, a condition signaling to an external controller, and energizing other equipment.

13. The method of claim 7 wherein said first predetermined response action is to activate the automatic retry.

14. The method of claim 1, wherein said first predetermined response action is selected from message only, pump shutdown, speed override in which said desired setpoint is changed to an alternate programmable preset speed setpoint, and process override in which said desired setpoint is changed to an alternate programmable preset process setpoint.

15. The method of claim 1 further comprising:

entering into data a maximum pump speed that the pump should run in the fluid pump system;

entering into data a minimum pump speed that the pump should run in the fluid pump system;

entering into data a positive threshold percentage that a process variable being monitored must remain within from a desired process variable setpoint;

entering a negative threshold percentage that the process variable being monitored must remain within from the desired process variable setpoint;

monitoring the pump speed using an internally estimated pump speed parameter and the process variable with said external process sensor;

checking automatically whether said process variable is within a range defined by said positive and negative threshold percentages about said process variable setpoint;

and initiating automatically the second predetermined response action either if said process variable is outside said range after expiration of a time period or if said process variable is not attained within said maximum and minimum speeds.

16. The method of claim 15, wherein said process variable is selected from flow, temperature, pressure, and level.

17. The method of claim 15, wherein said second predetermined response action is selected from message only, pump shutdown, speed override in which said desired process variable setpoint is changed to an alternate programmable preset speed setpoint, and process override in which said desired process variable setpoint is changed to an alternate programmable preset process variable setpoint.

18. The method of claim 15 further comprising using said method to detect a change in process fluid or system characteristics, loss of adequate suction, or equipment failure or wear.

19. The method of claim 1, wherein said second predetermined response action is selected from message only, pump shutdown, speed override in which a predetermined setpoint is changed to an alternate programmable preset speed setpoint, and process override in which said predetermined setpoint is changed to an alternate programmable preset process variable setpoint.

20. The method of claim 1 further comprising:

monitoring a state condition of a digital input;

and initiating automatically a third predetermined response action upon detection of a change in said state condition of said digital input and after expiration of a time delay said state condition does not further change.

21. The method of claim 20, wherein third predetermined response action is selected from message only, pump shutdown, speed override in which a predetermined setpoint is changed to an alternate programmable preset speed setpoint, and process override in which said predetermined setpoint is changed to an alternate programmable preset process variable setpoint.

22. The method of claim 20 wherein said state condition is either ON and OFF states of the digital input.

23. The method of claim 20 wherein said digital input is from a switching devices selected from a limit switch, a level switch, a pressure switch, a temperature switch, a flow switch, and a relay contact.

24. The method of claim 1 further comprising adjusting automatically the desired setpoint in response to the sensor signal based on a programmable multi-point scaling table that determines a multiplier value that is applied to the desired setpoint.

25. The method of claim 24 wherein said multi-point scaling table consists of a plurality of value pairs, wherein each value pair contains an input signal percentage that ranges from 0% to 100% and an output scaler percentage ranges from 0% to 150%, wherein said sensor signal is compared to the input signal percentage values in the scaling table, and wherein the output scaler percentage in the corresponding value pair matching the input signal percentage becomes the setpoint multiplier value.

26. The method of claim 25 further comprising using interpolation to calculate the setpoint multiplier value that fall between value pairs in the scaling table.

27. The method of claim 24 further comprising using said method in an application to empty a vessel to slow down the pump according to the pair values defined in the scaling table, wherein a suction pressure sensor provides the analog sensor signal to indicate level in the vessel being emptied.

28. A controller comprising a non-transitory computer readable medium comprising instructions implementing the method of claim 1.

29. A controller comprising a non-transitory computer readable medium comprising instructions implementing the method of claim 1 and provided integral with the VFD.

30. A controller comprising a non-transitory computer readable medium comprising instructions implementing the method of claim 15.

31. A controller comprising a non-transitory computer readable medium comprising instructions implementing the method of claim 15 and provided integral with the VFD.

34. A controller comprising a non-transitory computer readable medium comprising instructions implementing the method of claim 20.

35. A controller comprising a non-transitory computer readable medium comprising instructions implementing the method of claim 20 and provided integral with the VFD.

36. A controller comprising a non-transitory computer readable medium comprising instructions implementing the method of claim 24.

37. A controller comprising a non-transitory computer readable medium comprising instructions implementing the method of claim 24 and provided integral with the VFD.

2. A method of controlling operation of a centrifugal pump in a fluid pumping system having a variable frequency drive (VFD) powering an alternating current (AC) motor which turns said centrifugal pump, said method comprising:

internally monitoring automatically output current and voltage of the VFD to the AC motor without the need for an external sensor;

calculating automatically output power based on monitored values of said output current and voltage and not on torque or speed of the AC motor;

checking automatically whether said calculated output power is above a predetermined high power limit for a desired setpoint;

checking automatically whether said calculated output power is below a predetermined low power limit for said desired setpoint, wherein said high and low power limits are fixed values;

receiving feedback from an external process sensor, wherein said feedback is indicative of said desired setpoint;

initiating automatically a first predetermined response action if said calculated output power is either above said predetermined high power limit or below said predetermined low power limit;

wherein said high power limit is set to lowest of either power at the end of a performance curve of the pump, maximum rated motor power, or power rating of magnetic coupling of a magnetic drive pump or a canned motor pump, and wherein said low power limit is set for the highest of the performance curve of the pump or power required at minimum continuous recommended flow;

using a high power level delay which is a time period that the output power must exceed the high power limit before said predetermined response action is initiated;

monitoring an externally provided analog sensor signal;

and initiating automatically a second predetermined response action if in a signal threshold level mode said analog sensor signal crosses one or both preset levels in the same direction,

wherein each of said preset levels can initiate a separate response, or if in boundary mode, said analog sensor signal rising above a preset maximum value or drops below a preset minimum value, and in both modes, if after expiration of a time delay said analog sensor signal is still above one or both said preset levels if in a signal threshold level mode, or above or below said present maximum and minimum present values, respectively, if in boundary mode.

32. A controller comprising a non-transitory computer readable medium comprising instructions implementing the method of claim 2.

33. A controller comprising a non-transitory computer readable medium comprising instructions implementing the method of claim 2 and provided integral with the VFD.