AU2012200620B2 - A Pump Operation Method - Google Patents

Abstract

The present invention is directed to a method for operating a pump in a pumping station. The method includes the steps of: determining, with a controller, efficiency indicators for the pump corresponding to various operating speeds of the pump; storing the efficiency indicators; and operating the pump at the operating speed corresponding to the most efficient determined efficiency indicator. (0 E C%4 C) 0< a)' _ 0

Description

AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION STANDARD PATENT A PUMP OPERATION METHOD The following statement is a full description of this invention including the best method of performing it known to me: A PUMP OPERATION METHOD TECHNICAL FIELD 5 The present invention generally relates to pumping stations. The present invention has particular, although not exclusive application to waste water pumping stations. BACKGROUND 10 The reference to any prior art in this specification is not, and should not be taken as an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge. 15 Pumping stations 2 for emptying sewage wells (Figure 1) and filling water wells are known. As shown in Figure 1, waste water and sewage is supplied to the well 4 via an inlet 7 and the pumps 10 are configured to empty the well 4 via an outlet 9. 20 These pumping stations 2 include the well 4 in which liquid 6 is located, a level sensor 8 for sensing the liquid level in the well 4, a pair of pumps 10a, 10b for pumping liquid into or out of the well 4 as required, and a controller (not shown) in communication with sensor 8 and for controlling the operation of the pumps 10a, 1Ob based on the sensed liquid level in the well 4. Figure 1 25 shows various level trigger-points along the level sensor 8 in the form of liquid sensing electrodes. The controller independently activates or de-activates the pumps 10a, 10b with hysteresis in response to it sensing the liquid level via the electrodes. 30 Multiple pumps 10a, 1Ob are used to cater for pumping demand, but are more often used for redundancy purposes should one of the pumps fail in practice. It is known to install oversized pumps 10 having greater pumping capabilities to account for future increases in demand. However, operating oversized 2 pumps at higher speeds can be inefficient, particularly when the outlet 9 is too small or prone to blockages. It is an object of the present invention to provide an improved pump operation 5 method. SUMMARY OF THE INVENTION According to an aspect of the present invention, there is provided a method 10 for operating a pump in a pumping station, the method including the steps of: determining, with a controller, efficiency indicators for the pump corresponding to various operating speeds of the pump; storing the efficiency indicators; and operating the pump at the operating speed corresponding to the most 15 efficient stored efficiency indicator. Advantageously, the pump is operated at the optimized operating speed corresponding to the most efficient determined efficiency indicator to account for pumping station constraints such as an overly small pump outlet or pump 20 outlet blockages which can affect pumping efficiency. The step of storing may involve the storing of the efficiency indicators in a look-up table in memory. 25 The step of determining may involve sequentially varying the operating speed of the pump and determining corresponding efficiency indicators. The operating speed may be varied only once per actuation of the pump (i.e. pumping cycle). Alternatively, the operating speed may be varied multiple times per actuation of the pump. The operating speed may be sequentially 30 decreased by a predetermined step (e.g. 5%). The step of determining may further involve sequentially varying the operating speed of the pump for a number of different fluid levels in the pumping station.

3 The step of determining may be periodically performed (e.g. every quarter). The method may involve the steps of: determining efficiency indicators for another pump corresponding to 5 various operating speeds of other pump; and operating the other pump at the operating speed corresponding to the most efficient determined efficiency indicator of the other pump. The method may involve generally first operating the pump with the most 10 efficient determined efficiency indicator before any other pump. The method may further involve occasionally first operating any other pump to ensure that all pumps are operated at some stage. In a two pump embodiment, the most efficient pump may be operated first three quarters of the time whereas the other pump is operated one quarter of the time. 15 The method may further involve: determining an operation period efficiency indicator once the pump has operated in excess of a predetermined period; and reducing the operating speed of the pump responsive to the 20 determined operation period efficiency indicator being less than the most efficient determined efficiency indicator. The method may further include the step of operating the pump at operating speeds not corresponding to the most efficient determined efficiency indicator. 25 The method may involve adjusting the operating speed or a pump speed profile based upon a liquid level in a well. The method may involve adjusting the operating speed based upon stored historical demand data. 30 The method may further involve momentarily reversing the operating pump upon detecting a decrease in the efficiency indicator that is indicative of a blockage. Any speed variance of the operating pump may be retarded.

4 According to a further aspect of the present invention, there is provided a method for operating pumps in a pumping station, the method including the steps of: 5 determining, with a controller, efficiency indicators for pumps corresponding to operating speeds of the pumps; storing the efficiency indicators; and operating the pumps at the operating speeds corresponding to the most efficient stored efficiency indicators. 10 The operating speeds of the pumps may be the same speed. The step of determining may involve sequentially varying the same speed of the pumps and determining corresponding efficiency indicators. 15 Alternatively, the operating speeds of the pumps may be different speeds. The step of determining may involve sequentially varying the different speeds of the pumps based upon respective most efficient operating speeds of the individual pumps. The step of determining may involve varying the speed of one pump upwardly and the other pump downwardly from a collective most 20 efficient operating speed of the pumps. The most efficient efficiency indicators may be determined based on the efficiency of individual pumps. Alternatively, the most efficient efficiency indicators may be determined based on the efficiency indicators that would 25 give rise to the highest overall efficiency for the pumping station. The step of operating may involve operating the pumps at either the same speed or the different speeds with the most efficient determined efficiency indicator. 30 The method may include the step of occasionally operating any of the pumps at maximum speed.

5 According to a further aspect of the present invention, there is provided the controller configured to perform any one or more of the preceding methods. According to a further aspect of the present invention, there is provided a 5 media, such as a magnetic or optical disk or solid state memory, containing computer readable instructions for execution by a processor to thereby perform any one or more of the preceding methods. According to another aspect of the present invention, there is provided a 10 method for operating a pump in a pumping station, the method including the steps of: monitoring an efficiency indicator for the operating pump; and momentarily reversing the pump upon detecting a decrease in the efficiency indicator. 15 BRIEF DESCRIPTION OF THE DRAWINGS Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient 20 information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way. The Detailed Description will make reference to a number of drawings as follows: 25 Figure 1 is a schematic diagram of a pumping station for emptying a sewage well; Figure 2 is a block diagram showing a pump controller suitable for use with the pumping station of Figure 1; and 30 Figure 3 is a flowchart showing a pump operation method in accordance with an embodiment of the present invention.

6 DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to a controller 14 shown in Figure 2 that is configured to control the pumping 5 station 2 shown in Figure 1. Referring initially to Figure 1, the pumping station 2 includes a level sensor 8 for sensing the liquid level in a well 4, and a pair of pumps 10a, 10b (e.g. three-phase variable speed drive pumps) for pumping liquid out of the well 4 10 to at least partially empty the well 4. Waste water including storm water flows into the well 4 through inlet 7. The controller 14 is suitable for controlling the activation and deactivation of the pumps 10 based on the sensed liquid level in the well 4. The activation and deactivation trigger points along the level sensor 8 for a first pump 10a and a second pump 10b are clearly shown in 15 Figure 1. The controller 14 can also determine a well volume indicator (in the form of a variable or value), relating to the liquid volume in the well 4, using the liquid level sensor 8. Typically, the level sensor 8 includes an array of equidistant electrode sensing stations, and the uppermost triggered station corresponds to the well liquid level which, in turn, can be correlated to a 20 corresponding liquid volume in the well 4 (using a look-up table). Referring to Figure 2, a user interface 12 is provided to enable the pumping station supervisor to input data to the controller 14 and review controller data relating to the operation of the pumping station 2 on a display. For example, 25 the controller 14 is configured to display a sensed outflow rate indicator (F) relating to the output flow rate through outlet 9 of the activated pumps 10a, 1Ob, a sensed inflow rate indicator (l) relating to the inflow through inlet 7, and a net well volume rate indicator (V) (i.e. V = F - l). The inflow rate indicator () can be sensed with inflow sensor 13 and the outflow rate indicator (F) can be 30 sensed with outflow sensor 14. The user interface 12 is fixedly wired to fixed input/output (1/O) ports 16 of the controller 14 which, in turn, are interfaced using suitable circuitry to a microprocessor 19 that executes a software product 20.

7 The level sensor 8 and pumps 10 are wired to variable I/O ports 18 of the controller 14 which, in turn, are interfaced using suitable circuitry to the microprocessor 19. The wiring configuration between the variable I/O ports 18 and the peripheral hardware is prone to variation depending upon the type of 5 peripheral hardware (e.g. level sensor 8, pumps 10, etc.) used in the pumping station 2. The software product 20 includes instructions for processor 19 to execute, and enable controller 14 to perform the pump operation method 50 of the pumping station 2 described below. Software product 20 (including software routines) is typically provided in a memory device 17 of 10 microprocessor 19, or on a magnetic or optical disc 21 which microprocessor 19 can access by means of disc drive 23. An efficiency table shown in TABLE I below is also stored in the onboard memory device 17. According to an embodiment of the present invention, there is provided the 15 pump operation method 50 for operating the pumps 10a of the pumping station 2 as shown in Figure 3. At step 52, the pumping station 2 is installed or the pumps 10a, 10b are reconfigured. 20 At step 54, the controller 14 determines efficiency indicators (e) for each pump I0a, 1Ob corresponding to various operating speeds of the pumps 10a, 1Ob as shown, for example, in TABLE I below. The efficiency indicator (e) for each pump speed is determined by dividing the outflow flowrate indicator (F) 25 through outlet 9 mentioned above by the measured energy consumed by the pump(s) 10. TABLE I - Efficiency table efficiency (e) Speed Pump A Pump B Pump A and Pump B (Concurrent Operation) 100% 0.80 0.78 0.74 95% 0.80 0.79 0.78 8 90% 0.83 0.80 0.80 85% 0.85 0.83 0.81 80% 0.89 0.85 0.82 75% 0.85 0.92 0.83 70% 0.80 0.85 0.85 65% 0.75 0.80 0.89 60% 0.70 0.75 0.90 55% 0.70 0.73 0.87 Initially, the pumps 10 are activated at 100% both separately and then together at the same speed for three pumping cycles so as to complete the first row in the table above. Then, the pumps 10 are activated at 95% both 5 separately and together for the next three pumping cycles, and so on. The operating speeds are sequentially decreased by a predetermined step (e.g. 5%) for each row when forming TABLE I. This process involves sequentially decreasing the operating speed of each and both pumps 10 and determining corresponding efficiency indicators. Each pump operating speed is varied only 10 once per actuation of the pump (i.e. pumping cycle). The resulting efficiency TABLE I is stored in the onboard memory 17 of microprocessor 19. At step 56, once efficiency TABLE I is created, the controller 14 operates each pump 10 at the operating speed corresponding to the most efficient (i.e. 15 highest) determined efficiency indicator. That is, pump A 10a is operated at 80% maximum speed (yielding max. e = 0.89) and pump B is operated at 75% maximum speed (yielding max. e = 0.92) when actuated. Advantageously, each pump 10 is operated at the optimized operating speed corresponding to the highest determined efficiency indicator to account for pumping station 20 constraints such as an overly small pump outlet or pump outlet blockages which can affect pumping efficiency. If the combined efficiency indicator (e) for both pumps 1Oa, 1Ob is higher than those efficiency indicators of the respective pumps 10a, 10b, then the 25 controller 14 can instead concurrently operate both pumps 10 at the common 9 operating speed corresponding to the most efficient (i.e. highest) determined efficiency indicator. The controller 14 preferentially first operates pump B 10b with the highest 5 determined efficiency indicator before pump A 10a. The controller 14 occasionally first operates pump A 10a to ensure that all pumps 10a, 10b are operated at some stage. Elaborating further, the most efficient pump 10b is operated first three quarters of the time whereas the other pump 10a is operated one quarter of the time. This ratio can be varied as desired. 10 Periodically, the controller 14 operates each pump 10 at a maximum speed (100%) not corresponding to the highest determined efficiency indicator for a pump cycle to purge the outlet 9 of any blockages and debris. Several pumps 10 can also be run at full speed for a short period if required to purge out the 15 system. In the event that the controller 14 detects that the monitored efficiency (e) of an operating pump 10a, 10b suddenly decreases which is indicative of a blockage (e.g. rag in a pipe or fatty build-up on pump impeller), the controller 20 14 can momentarily reverse the pump 10a, 10b to remove the blockage with reverse flow before resuming normal pump operation once again. In practice, the pumping station 2 may be part of a larger network including many connected pumping stations 2. Pressure differentials between the 25 pumping stations 2 can affect the pump efficiencies. To combat this issue, the controller 14 can re-determine an operation period efficiency indicator (e) once a pump 10 has operated in excess of a predetermined period (e.g. 2 minutes) during a pump cycle. The controller 14 can then reduce the operating speed of the pump 10 responsive to the re-determined operation 30 period efficiency indicator (e) being less than the highest determined efficiency indicator (e), in which case the pressure differential is affecting the pump efficiency. The operating speed can be varied until an optimum efficiency indicator is determined and this efficiency indicator can be stored for 10 later use in the event that the controller 14 detects multiple pumping stations concurrently pumping in the future. At query step 58, the controller 14 queries whether a recalculation period (e.g. 5 3 months) for recalculating efficiency TABLE I has expired. If so, the method 50 returns to step 54 where TABLE I can be recalculated (e.g. every quarter). Alternatively, the method 50 returns to step 56 where the existing efficiency indicators (e) are used to operate the pumps 10a, 1Ob at desired speeds. 10 A person skilled in the art will appreciate that many embodiments and variations can be made without departing from the ambit of the present invention. The liquid level in the well 4 can affect the efficiency of the pumps 10. 15 Typically, the higher the liquid level, the greater the efficiency of the pump for a specific pump speed. In some embodiments, the controller 14 can adjust the pump speed or pump speed profile based upon the liquid level sensed with level sensor 8. 20 In one embodiment, efficiency indicators (e) for a range of pump speeds, such as the range of pump speeds as shown in Table I above, may be calculated for a range of liquid levels sensed with sensor 8. Therefore, a number of efficiency tables may be generated and stored in memory at step 54 of Figure 3, each table corresponding to a respective liquid level (e.g. 25%, 50% etc). 25 At step 56, the relevant efficiency table may be determined based on the liquid level sensed with the level sensor 8. Typically, the relevant efficiency table would correspond with a liquid level that is closest to the sensed liquid level or interpolation between tables may otherwise be undertaken. Then, the 30 pumps 10 may be operated at operating speeds corresponding to the most efficient efficiency indicators available in the relevant efficiency table corresponding to the correct liquid level.

11 In one embodiment, the controller 14 may adjust the pump speed based upon stored historical demand data. In this manner, the efficiency based pump operation method 50 can be overridden and pump speeds can be increased to cope with demand at times when the inflow through inlet 7 is known to be 5 high. In the preferred embodiment, the efficiency indicators (e) were calculated for each pump actuation at a single pump operating speed. Alternatively, the operating speed may be varied multiple times during a single actuation of the 10 pump so that multiple efficiencies (e) can be determined during a single pump cycle. A change in speed can be triggered by a change in the measured well level. In the preferred embodiment, both pumps 10a, 10b can be concurrently 15 operated at the same speed. Alternatively, the operating speed of the pumps 10a, 10b can be different optimized speeds. Elaborating further, step 54 can involve sequentially varying the different speeds of the pumps 10 based upon respective highest efficiency operating speeds of the individual pumps 10a, 10b in TABLE I. For example, the step of determining the optimum pump 20 speeds can involve incrementally varying the speed of pump A upwardly (as it has the higher individual efficiency speed of 80%) and pump B downwardly (as it has the lower individual efficiency speed of 75%) from the highest combined speed of 60% until an optimal efficiency indicator is determined. 25 The preferred embodiment relates to pumps 10 with variable frequency drives (VFDs) able to be readily varied in operating speed. Preferably, the speed variance of the pumps 10 is retarded (i.e. speed cannot incrementally change in excess of a certain range per unit time), as widely varying speeds would otherwise adversely affect the determination of the efficiency (e) and other 30 flow calculations. Alternatively, direct on line (DOL) pumps may be used. In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. It is to be understood that the invention is not limited to specific features shown or 12 described since the means herein described comprises preferred forms of putting the invention into effect.

Claims (24)

1. A method for operating a pump in a pumping station, the method including the steps of: determining, with a controller, efficiency indicators for the pump corresponding to various operating speeds of the pump; storing the efficiency indicators; and operating the pump at the operating speed corresponding to the most efficient stored efficiency indicator.

2. The method as claimed in claim 1, wherein the step of storing includes storing the efficiency indicators in a look-up table in memory.

3. A method according to any one of the preceding claims, wherein the step of determining includes sequentially varying the operating speed of the pump and determining corresponding efficiency indicators.

4. A method according to any one of the preceding claims, wherein the operating speed is varied only once per actuation of the pump.

5. A method according to any one of the preceding claims 1 to 3, wherein the operating speed is varied multiple times per actuation of the pump.

6. The method as claimed in claim 3, wherein the operating speed is sequentially decreased by a predetermined step.

7. A method according to any one of the preceding claims, wherein the step of determining is based upon the fluid level of the pumping station.

8. A method according to any one of the preceding claims, wherein the step of determining further includes sequentially varying the operating speed of the pump for a number of different fluid levels in the pumping station. 14

9. A method according to any one of the preceding claims, wherein the step of determining is periodically performed.

10. A method according to any one of the preceding claims, wherein the method further includes the steps of: determining efficiency indicators for another pump corresponding to various operating speeds of the other pump; and operating the other pump at the operating speed corresponding to the most efficient determined efficiency indicator of the other pump.

11. The method as claimed in claim 10, further including first operating a pump with the most efficient determined efficiency indicator before any other pump.

12. A method according to any one of claims 10 to 11, further including occasionally first operating any pump to ensure that all pumps are operated at some stage during an operating period.

13. A method according to any one of claims 10 to 12, wherein the most efficient pump is operated during the first three quarters of an operating period, and the other pump is operated during one quarter of the operating period.

14. A method according to any one of claims 1 to 9, wherein the method further includes: determining an operation period efficiency indicator once the pump has operated in excess of a predetermined period; and reducing the operating speed of the pump responsive to the determined operation period efficiency indicator being less than the most efficient determined efficiency indicator.

15. A method according to any one of claims 1 to 9, wherein the method includes the step of operating the pump at operating speeds not corresponding to the most efficient efficiency indicator. 15

16. A method according to any one of the preceding claims, wherein the method includes adjusting the operating speed based upon stored historical demand data.

17. A method according to any one of the preceding claims, wherein the method further includes momentarily reversing an operating pump upon detecting a decrease in the efficiency indicator that is indicative of a blockage.

18. A method for operating pumps in a pumping station, the method including the steps of: determining, with a controller, efficiency indicators for pumps corresponding to operating speeds of the pumps; storing the efficiency indicators in memory; identifying a most efficient efficiency indicator for each pump based on the stored efficiency indicators; and operating the pumps at the operating speeds corresponding to the most efficient efficiency indicators.

19. The method as claimed in claim 18, wherein the step of determining may involve sequentially varying the operating speeds of the pumps and determining corresponding efficiency indicators.

20. The method as claimed in claim 19, wherein the step of determining includes varying the speed of one pump upwardly and another pump downwardly from collective most efficient operating speeds of the pumps.

21. The method according to any one of claims 18 to 20, wherein the most efficient efficiency indicators are determined based on the efficiency of individual pumps.

22. The method according to any one of claims 18 to 20, wherein the most efficient efficiency indicators are determined based on the efficiency indicators that would give rise to the highest overall efficiency for the pumping station. 16

23. A controller configured to perform any one or more of the preceding claims.

24, A computer readable media containing computer readable instructions for execution by a processor to thereby perform any one or more of the methods in the preceding claims I to 22. Dated this 30 " day of March 2016 MULTITRODE PTY LTD by its attorneys Cullens Patent and Trade Mark Attorneys