AU2008229836B2

AU2008229836B2 - Pump Control Method

Info

Publication number: AU2008229836B2
Application number: AU2008229836A
Authority: AU
Inventors: Stephen John Carson-Rowland; Stuart Mcmillan Duncan
Original assignee: MultiTrode Pty Ltd
Current assignee: MultiTrode Pty Ltd
Priority date: 2008-01-21
Filing date: 2008-10-09
Publication date: 2009-10-08
Anticipated expiration: 2028-10-09
Also published as: AU2008229836A1

Description

AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION STANDARD PATENT PUMP CONTROL METHOD The following statement is a full description of this invention including the best method of performing it known to me: PUMP CONTROL 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 1a) and filling water wells (Figure 1b) are known. These pumping stations 2 typically include a 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 20 controlling the operation of the pumps 10a, 10b based on the sensed liquid level in the well 4. Figure 1 shows various level trigger-points along the level sensor 8 in the form of 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. 25 With reference to Figure 1, the controller activates the pumps 10a, 10b to operate in a predetermined sequence, whereby a first pump 10a is always activated before the second pump 10b is activated and then the first pump 10a is always deactivated after the second pump 10b is deactivated. The first 30 pump 10a is activated more often and for longer than the second pump 10b, and is therefore prone to more wear. Accordingly, the first pump 10a typically needs to be serviced or replaced more frequently than the second pump 1Ob which is undesirable.

2 It is an object of the present invention to provide an alternative method for determining an operation sequence of pumps in a pumping station. SUMMARY OF THE INVENTION 5 According to an aspect of the present invention, there is provided a method for determining an operation sequence of pumps in a pumping station, the method including the steps of: determining, with computational means, one or more operational 10 efficiency indicators for respective the pumps; and determining, with the computational means, the operation sequence in accordance with the efficiency indicators; and responsive to the foregoing steps being performed a predetermined number of times, setting with the computational means the pumps to operate 15 in accordance with another operation sequence. The method may further include the step of operating the pumps in accordance with the determined operation sequence. The most efficient pump may be the first to be activated and then the last to be deactivated 20 The operation sequence may include the activation sequence that the pumps are to be activated. The pumps may be sequentially activated in accordance with descending efficiency indicators whereby the most efficient pumps are activated first. 25 The operation sequence may include the deactivation sequence that the pumps are to be deactivated. The pumps may be sequentially deactivated in accordance with ascending efficiency indicators whereby the least efficient pumps are deactivated first. 30 The step of determining efficiency indicators may involve sensing the output liquid flow rates of respective pumps or calculating the output liquid flow rates of respective pumps using a sensed liquid level which can be altered by the pumps. The step of determining efficiency indicators may further involve 3 sensing the input currents of respective pumps. The step of determining efficiency indicators may further involve determining the input powers of the pumps using respective input currents. The step of determining efficiency indicators may further involve determining the input energies to the pumps by 5 integrating respective input powers over time. The efficiency indicators may be calculated by dividing the sensed output liquid flow rates by respective input energies to the pumps. The method may further include the step of periodically operating the pumps 10 in accordance with another operation sequence. The step of periodically operating the pumps may include the step of determining a count of the number of pumping operations performed. The step of periodically operating the pumps may further include the step of operating the pumps in accordance with the other operation sequence when the determined count reaches a 15 predetermined number. According to another aspect of the present invention, there is provided a a method for determining an operation sequence of pumps in a pumping station, the method including the steps of: 20 determining, with computational means, one or more operational efficiency indicators for respective the pumps; and determining, with the computational means, the operation sequence in accordance with ascending or descending efficiency indicators; and responsive to the foregoing steps being performed a predetermined 25 number of times, setting with the computational means the pumps to operate in accordance with another operation sequence determined in accordance with ascending efficiency indicators. According to another aspect of the present invention, there is provided a 30 method for determining an operation sequence of pumps in a pumping station, the method including the steps of: sensing, with sensors, one or more operational parameters for respective the pumps; and 4 determining, with computational means, the operation sequence using the sensed operational parameters; and responsive to the foregoing steps being performed a predetermined number of times, setting with the computational means the pumps to operate 5 in accordance with another operation sequence. According to another aspect of the present invention, there is provided a method for determining an operation sequence of pumps in a pumping station, the method including the steps of: 10 sensing, with sensors, the one or more output liquid flow rates for respective the pumps or calculating the one or more output liquid flow rates of respective the pumps using a sensed liquid level which can be altered by the pumps; and determining, with computational means, the operation sequence using 15 the sensed or calculated output liquid flow rates; and responsive to the foregoing steps being performed a predetermined number of times, setting with the computational means the pumps to operate in accordance with another operation sequence. 20 According to a further aspect of the present invention, there is provided a 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. 25 According to a further aspect of the present invention, there is provided computational means configured to perform any one or more of the preceding methods. Preferably, the computational means is a pump controller. According to a further aspect of the present invention, there is provided a 30 pumping station or a pump controller configured to: receive one or more operational parameters from respective sensors for pumps; and determine an operation sequence of the pumps using the received operational parameters; and 4a responsive to both receiving the operational parameters and determining the operation sequence a predetermined number of times, set the pumps to operate in accordance with another operation sequence. 5 According to a final aspect of the invention there is provided a pump controller including: a processor in communication with ports for connection to pumps; and a memory either on-board or in communication with the processor, the 10 memory containing a software product including: routines for receiving one or more operational parameters from respective sensors for the pumps; and routines for determining an operation sequence of the pumps using the received operational parameters; and 15 routines which, responsive to both receiving the operational parameters and determining the operation sequence a predetermined number of times, set the pumps to operate in accordance with another operation sequence. 20 The software product may further include routines for displaying an indicator of energy consumed by at least one pump.

BRIEF DESCRIPTION OF THE DRAWINGS Preferred features, embodiments and variations of the invention may be 5 discerned from the following Detailed Description which provides sufficient 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: 10 Figure la is a schematic diagram of a pumping station for emptying a sewage well; Figure 1b is a schematic diagram of a pumping station for filling a water well; 15 Figure 2 is a block diagram of a pump controller of a pumping station, the controller interfaced to a user interface and peripheral hardware; Figure 3 is a flowchart showing a method in accordance with an embodiment 20 of the present invention, the method being for determining the operation sequence of the pumps in the pumping station of Figure 2; and Figure 4 is a flowchart showing a method for determining an operational efficiency indicator for each pump and that forms a part of the method of 25 Figure 3. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference 30 to a controller 14 of a pumping station 2 as shown in Figure 2. The pumping station 2 includes a level sensor 8 for sensing the liquid level in a well, and a pair of pumps 10a, 1Ob (e.g. variable speed drive (VFD) pumps) for pumping liquid into or out of the well as required. The controller 14 is suitable for controlling the operation of the pumps 10 based on the sensed liquid level in 6 the well. A user interface 12 is provided to enable a user to input data to the controller 14 and review controller data relating to the operation of the pumping station 2 on a display. The user interface 12 is fixedly wired to fixed input/output (1/O) ports 16 of the controller 14 which, in turn, are interfaced 5 using suitable circuitry to a microprocessor 19 that executes a software product 20. The level sensor 8 and pumps 10 are wired to variable 1/O ports 18 of the controller 14 which, in turn, are interfaced using suitable circuitry to the 10 microprocessor 19. The wiring configuration between the variable 1/O ports 18 and the peripheral hardware is prone to variation depending upon the type of 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 perform a method 50 for determining an operation sequence of the pumps 10 15 in the pumping station 2. Software product 20 (including software routines) is typically provided as firmware in an integrated circuit memory device 17 or as a magnetic or optical disc 21 which microprocessor 19 can access by means of disc drive 23. 20 According to an embodiment of the present invention, there is provided the method 50 performed by controller 14 and for determining the operation sequence of the pumps 10 in the pumping station 2. The method 50 is described in detail below with reference to Figure 3. 25 Initially, the method begins at step 52 upon power up of the controller 14. At step 54, the software product 20 initialises a loop counter COUNT stored in memory 17. The loop counter COUNT keeps a record of the number of consecutive times that step 60 relating to an efficiency based pump operation 30 sequence is performed, before an alternative pump operation sequence is instead performed. The method 50 generally involves performing the efficiency based pump operation sequence set instep 60, although periodically the pumps are operated in accordance with an alternative operation sequence set in step 72.

7 At step 56, the software product 20 loads an efficiency indicator register (not shown but formed in the memory 17 of microprocessor 19) with default pumping efficiency indicators (i.e. variables) for each of the pumps 10. These 5 default efficiency indicators are initially used to determine the pump operation sequence, until actual efficiency indicators are later determined at step 64 when the pumps 10 are actually operated. At step 58, the software product 20 determines whether the loop counter 10 COUNT has reached a predetermined maximum number MAXCOUNT (e.g. ten) stored in memory 17. The method proceeds to step 60 unless the loop counter COUNT is equal to MAXCOUNT, in which case the method proceeds to step 70 to perform the alternative pump operation sequence described in detail below. 15 At step 60, the software product 20 determines the operation sequence of the pumps 10 in accordance with the efficiency indicators stored in the efficiency indicator register. The operation sequence includes an activation sequence that the pumps 10 are to be activated. The pumps 10 are to be sequentially 20 activated in accordance with descending efficiency indicators whereby the most efficient pump is activated first, followed by pumps of lessening efficiency (in descending order). Similarly, the operation sequence includes a deactivation sequence that the pumps 10 are to be deactivated. The pumps 10 are to be sequentially deactivated in accordance with ascending efficiency 25 indicators whereby the least efficient pump is deactivated first, followed by pumps of increasing efficiency (in increasing order). The foregoing pump operation sequence ensures that the most efficient pumps are run for most of the time whereas the least efficient pumps are run 30 least of the time. That is, the most efficient pump is the first to be activated and then the last to be deactivated whereas the least efficient pump is the last to be activated and then the first to be deactivated. The foregoing pump operation sequence increases the time required between services and replacement of pumps 10 at the pumping station 2.

8 The determined operation sequence is set as the pump operation sequence to be used when the controller 14 next operates the pumps 10. 5 At step 62, the controller 14 determines, in accordance with sensed information from the liquid level sensor 8, that pump operation is required. Accordingly, the controller 14 operates the pumps 10 in accordance with the operation sequence set in step 60 (or step 72 as described below). 10 At step 64, the controller 14 determines new operational efficiency indicators for respective pumps 10 as they are operated, and stores them in the efficiency indicator register. Those pumps 10 which were not operated during step 62 retain previous operational efficiency indicators. A method 80 for determining an operational efficiency indicator for each pump using sensed 15 pump parameters is described later below with reference to Figure 4. Upon completion of the pumping operation, the method 50 proceeds to step 66. At step 66, the loop counter COUNT is incremented to indicate that another pumping operation has been performed. 20 As previously described with reference to step 58, whenever the loop counter COUNT equals the predetermined maximum number MAXCOUNT, the controller 14 periodically operates the pumps in accordance with the alternative operation sequence shown in steps 70 and 72. 25 At step 70, the software product 20 initialises the loop counter COUNT. At step 72, the software product 20 determines and sets an alternative operation sequence of the pumps 10. This alternative sequence is used to 30 ensure that the lesser efficient pumps, which are infrequently (and possibly never) operated, are operated so that their efficiency indicators can be determined and updated at step 64. As before, the alternative operation sequence is determined using efficiency indicators stored in the efficiency indicator register.

9 The alternative operation sequence includes an activation sequence that the pumps 10 are to be activated. The pumps 10 are to be sequentially activated in accordance with ascending efficiency indicators whereby the least efficient 5 pump is activated first, followed by pumps of increasing efficiency (in increasing order). Similarly, the alternative operation sequence includes a deactivation sequence that the pumps 10 are to be deactivated. The pumps 10 are to be sequentially deactivated in accordance with descending efficiency indicators whereby the most efficient pump is deactivated first, 10 followed by pumps of decreasing efficiency (in decreasing order). The method 80 for determining an operational efficiency indicator for each pump using sensed pump parameters is now described with reference to Figure 4. 15 Initially, the method 80 begins at step 82 upon operation of the pump 10. The pump 10 is fitted with a flow rate sensor (not shown) coupled to the controller 14 to enable the controller 14 to sense the rate of flow of liquid 20 being pumped. At step 84, the controller 14 receives the output liquid flow rate of the pump 10 sensed by the flow rate sensor. The pumping station 2 further includes ammeters (not shown) coupled to the controller 14 to sense the input currents of respective pumps 10. At step 86, 25 the controller 14 receives the input current of the pump 10 sensed by its ammeter. The pumping station 2 further includes voltmeters (not shown) coupled to the controller 14 to sense the input voltages of respective pumps 10. At step 86, 30 the controller 14 further receives the input voltage of the pump 10 sensed by its voltmeter.

10 At step 88, the controller 14 determines the input power of the pump 10, which is typically a 3-phase pump, using the sensed 3-phase input current and sensed 3-phase pump voltage. 5 At step 90, the controller 14 determines the input energy supplied to the pump 10 by integrating the determined input power over time. At step 92, the controller 14 calculates an efficiency indicator of the pump 10 by dividing the sensed output liquid flow rate by the determined input energy 10 supplied to the pump 10. At step 94, the method 80 ends. As previously mentioned, the software product 20 would typically be provided 15 on a media, such as a magnetic or optical disk 21 or solid state memory 17, which contains computer readable instructions for execution by the controller 14 to thereby perform the preceding method 50. The controller 14 is a type of computational device configured to perform the 20 preceding methods. 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. 25 In the preferred embodiment, the efficiency indicator for each pump was calculated by dividing the sensed output liquid flow rate of the pump by the determined input energy supplied to the pump. The skilled person will appreciate that there are a number of ways to determine indicators of 30 efficiency that indicate the relative efficiencies of the pumps. For example, if the pumps are identical and therefore have substantially the same input power consumption, the sensed output liquid flow rates could alone be used as efficiency indicators.

II In the preferred embodiment, a separate user interface 12 was interfaced to fixed input/output (I/0) ports 16 of the controller 14 with a wiring loom. In an alternative embodiment, the controller 14 may integrally include the user 5 interface 12 so that the controller 14 and user interface 12 form a single unit. In the preferred embodiment, the memory 17 was integrated with the microprocessor 19. In an alternative embodiment, the memory may be discrete, and interfaced to the microprocessor 19. 10 In the preferred embodiment, the pump 10 was fitted with a flow rate sensor and the controller 14 received the output liquid flow rate of the pump 10 sensed by the flow rate sensor. In an alternative embodiment, the well 4 is fitted with a volume (or liquid level) sensor that is coupled to the controller 14, 15 and the controller 14 can calculate the output liquid flow rate of the pump 10 using the sensed volume of the well liquid 6 (or liquid level) over time. In an alternative embodiment, the volume sensor may be substituted by a weight sensor. 20 In one embodiment, the controller 14 can calculate the cost of energy (or power) consumed by each pump 10 and display these costs upon a display. Each cost may or may not be displayed as a monetary value. The total cost of energy consumed by all of the pumps 10 may also be displayed. Software product 20 includes routines for displaying the cost (or costs) of energy. 25 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 described since the means herein described comprises preferred forms of 30 putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted by those skilled in the art.

Claims

1. A method for determining an operation sequence of pumps in a pumping station, the method including the steps of: determining, with computational means, one or more operational efficiency indicators for the pumps; determining, with the computational means, the operation sequence in accordance with the efficiency indicators; and responsive to the foregoing steps being performed a predetermined number of times, setting with the computational means the pumps to operate in accordance with another operation sequence.

2. A method as claimed in claim 1, wherein the method further includes the step of operating the pumps in accordance with the determined operation sequence.

3. A method as claimed in claim 2, wherein the most efficient pump is the first to be activated and then the last to be deactivated.

4. A method as claimed in any one of the preceding claims, wherein the operation sequence includes the activation sequence that the pumps are to be activated.

5. A method as claimed in claim 4, wherein the pumps are to be sequentially activated in accordance with descending efficiency indicators whereby the most efficient pumps are activated first.

6. A method as claimed in claim 4 or claim 5, wherein the operation sequence further includes the deactivation sequence that the pumps are to be deactivated.

7. A method as claimed in any one of the preceding claims, wherein the step of determining efficiency indicators involves sensing the output liquid flow rates of respective pumps and sensing the input currents of respective pumps. 13

8. A method as claimed in any one of the preceding claims, further including the step of operating the pumps in accordance with the other operation sequence wherein the least efficient pump is the first to be activated and then the last to be deactivated.

9. A method for determining an operation sequence of pumps in a pumping station, the method including the steps of: determining, with computational means, one or more operational efficiency indicators for the pumps; determining, with the computational means, the operation sequence in accordance with descending efficiency indicators; and responsive to the foregoing steps being performed a predetermined number of times, setting with the computational means the pumps to operate in accordance with another operation sequence determined in accordance with ascending efficiency indicators.

10. A method for determining an operation sequence of pumps in a pumping station, the method including the steps of: sensing, with sensors, one or more operational parameters for the pumps; and determining, with computational means, the operation sequence using the sensed operational parameters; and responsive to the foregoing steps being performed a predetermined number of times, setting with the computational means the pumps to operate in accordance with another operation sequence.

11. A method for determining an operation sequence of pumps in a pumping station, the method including the steps of: sensing, with sensors, one or more output liquid flow rates for the pumps or calculating one or more output liquid flow rates of the pumps using a sensed liquid level which can be altered by the pumps; and determining, with computational means, the operation sequence using the sensed or calculated output liquid flow rates; and 14 responsive to the foregoing steps being performed a predetermined number of times, setting with the computational means the pumps to operate in accordance with another operation sequence.

12. A storage media containing computer readable instructions for execution by a processor to thereby perform a method as claimed in any one of the preceding claims.

13. A pump controller configured to perform a method as claimed in any one of claims 1 to 11.

14. A pump controller configured to: receive one or more operational parameters from sensors for pumps; determine an operation sequence of the pumps using the received operational parameters; and responsive to both receiving the operational parameters and determining the operation sequence a predetermined number of times, set the pumps to operate in accordance with another operation sequence.

15. A pump controller as claimed in claim 14, further configured to operate the pumps in accordance with the determined operation sequence.

16. A pump controller as claimed in any one of the preceding claims, wherein the operation sequence includes the activation sequence that the pumps are to be activated and the deactivation sequence that the pumps are to be deactivated.

17. A pump controller as claimed in any one of the preceding claims, wherein the operational parameters include sensed output liquid flow rates of respective pumps and sensed input currents of respective pumps.

18. A pump controller as claimed in any one of the preceding claims, further configured to periodically operate the pumps in accordance with another operation sequence. 15

19. A pump controller including: a processor in communication with ports for connection to pumps; and a memory either on-board or in communication with the processor, the memory containing a software product including: routines for receiving one or more operational parameters from sensors for the pumps; routines for determining an operation sequence of the pumps using the received operational parameters; and routines which, responsive to both receiving the operational parameters and determining the operation sequence a predetermined number of times, set the pumps to operate in accordance with another operation sequence.

20. A pump controller as claimed in claim 19, wherein the software product further includes routines for displaying an indicator of energy consumed by at least one pump.

21. A method substantially as herein described with reference to Figures 3 and 4.