Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D15/00—Control, e.g. regulation, of pumps, pumping installations or systems
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D15/00—Control, e.g. regulation, of pumps, pumping installations or systems
  • F04D15/0066—Control, e.g. regulation, of pumps, pumping installations or systems by changing the speed, e.g. of the driving engine
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
  • F04B49/06—Control using electricity
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D15/00—Control, e.g. regulation, of pumps, pumping installations or systems
  • F04D15/0077—Safety measures
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D15/00—Control, e.g. regulation, of pumps, pumping installations or systems
  • F04D15/02—Stopping of pumps, or operating valves, on occurrence of unwanted conditions
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D15/00—Control, e.g. regulation, of pumps, pumping installations or systems
  • F04D15/02—Stopping of pumps, or operating valves, on occurrence of unwanted conditions
  • F04D15/0209—Stopping of pumps, or operating valves, on occurrence of unwanted conditions responsive to a condition of the working fluid
  • F04D15/0218—Stopping of pumps, or operating valves, on occurrence of unwanted conditions responsive to a condition of the working fluid the condition being a liquid level or a lack of liquid supply

Definitions

• the present invention relates generally to the field of pumps, and, more specifically, the present invention relates to variable frequency drive pumps and methods for operating such pumps.
• VFD pumps Variable frequency drive pumps
• submersible pumps for example, for pumping fluids in mining applications such as in mining shafts, wells or at construction sites.
• submersible pumps are submersed, wholly or partly, during long periods of time both when they are in operation and when in an off-state.
• sensors such as a level switch, are used to sense the fluid level.
• these level sensors may, for example, be blocked or be subjected to a level shift due to a collision with subjects in the fluid such as a tree branch, and, thus, delivering an error signal.
• the pump operates in a dynamic environment and thus the pump should be able to operate in an efficient way in large range of head/ pressure.
• the head corresponds to the height the pump, using a given power, is able to lift a given amount of liquid, for example, water, see Fig. 3 where a typical pump curve is indicated by the line 30.
• the efficiency of a pump may, as indicated in Fig. 3, be reduced at low flows (Q).
• Q flows
• This entails that a large starting torque of the pump motor is required in order to initiate the rotating of the pump impeller. Often a maximum starting torque is even required in order to start the rotation and the motor has to be operated at a maximum torque during a significant period of time. This consumes large amounts of energy and also wears the pump impeller and the motor.
• one object of the present invention is to provide an improved pump, a pump system including such a pump, a computer program, a control device for such a pump and methods for controlling such a pump and pump systems in an efficient way with respect to energy consumption
• Another object of the present invention is to provide an improved pump, a pump system including such a pump, a computer program, a control device for such a pump and methods for controlling such a pump and pump systems in an efficient way with respect to durability of the pump. It is a further object of the present invention to provide an improved pump, pump system including such a pump, a computer program, a control device for such a pump and a method for controlling such a pump and pump systems in a manner that reduces the wear of the pump and extends the pump life.
• pump speed is defined as the numbers of revolutions per time unit of the pump.
• a method for operating a pump having an inlet and an outlet comprising variable frequency drive means adapted to drive a motor of the pump.
• the method comprises the steps of obtaining operating parameters of the pump substantially continuously from the variable frequency means, the operating parameters indicating pump conditions; and controlling the variable frequency drive means based on the obtained operating parameters, wherein the operation of the motor is adjusted to the pump conditions.
• a pump comprising variable frequency drive means adapted to drive a motor of the pump; and control device communicating with the variable frequency drive means, the control device comprising processing means and being adapted to obtain values corresponding to operating parameters of the pump, the operating parameters indicating pump conditions, from the variable frequency means and to send control instructions to the variable frequency drive means based on the obtained operating parameters for controlling the variable frequency drive means, wherein the operation of the motor is adjusted to the pump conditions.
• a computer program product loadable into a memory of a digital computer device including software code portions for performing the method of according to the first aspect of the present invention when the computer program product is run on the computer device.
• a pump system including a pump comprising variable frequency drive means adapted to drive a motor of the pump; and control device communicating with the variable frequency drive means, the control device comprising processing means and being adapted to obtain values corresponding to operating parameters of the pump from the variable frequency means, the operating parameters indicating pump conditions, and to send control instructions to the variable frequency drive means based on the operating parameters for controlling the variable frequency drive means, wherein the operation of the motor is adjusted to the pump conditions.
• a control device for a pump is characterized in that it is adapted to communicate with the variable frequency drive means, the control device comprising processing means and being adapted to obtain values corresponding to operating parameters of the pump from the variable frequency means, the operating parameters indicating pump conditions, and to send control instructions to the variable frequency drive means based on the operating parameters for controlling the variable frequency drive means, wherein the operation of the motor is adjusted to the pump conditions.
• the present invention is based on the idea of obtaining operating parameters of the pump substantially continuously from the variable frequency means, which operating parameters indicate pump conditions; and controlling the variable frequency drive means based on the obtained operating parameters, wherein the operation of the motor is adjusted to the pump conditions.
• the pump is operated in an efficient way with respect to energy consumption and durability of the pump.
• the wear of the pump parts such as the impeller and the seals is reduced the pump life can be extended. Due to the fact that all information required for the control of the pump and pump motor and variable frequency means is obtained from the variable frequency means and/ or the motor itself, no external sensors are required.
• the operating parameters in any one of: the DC link power of the variable frequency unit, the current of the variable frequency unit, or the torque of the motor.
• the obtained operating parameter value of the variable frequency unit is compared with a predetermined parameter level substantially continuously; and if it is determined that the parameter value is lower than the predetermined level, the operation of the pump motor is stopped during a period of time having a predetermined length. Moreover, the motor is restarted at a first speed level when the predetermined period of time has expired; the presence of fluid at the inlet is checked by comparing the parameter value with the predetermined parameter level; and the speed of the motor is increased from the first level if it is determined that the parameter value is higher than the predetermined parameter level.
• the snoring operation problem which, as discussed above, causes extra wear of the pump, and in particular of the impeller, may cause the pump motor to overheat and also leads to that unnecessary power is consumed is dealt with, and an efficient way of operating a VFD pump in respect of power consumption and durability can thereby be obtained.
• the pump life can be extended owing to the fact that the wear of pump parts such as the impeller, seals and suction cover is significantly reduced.
• maintaining the output power of the pump at a substantially constant level Furthermore, the operating parameter value is compared with a predetermined parameter level substantially continuously; if the parameter value is lower than the predetermined power level, the speed of the motor required to obtain the predetermined power level is calculated; and the pump is ran at the calculated speed.
• the calculated speed is compared with the maximum allowed speed of the pump; and if the calculated speed is higher than the maximum allowed speed of the pump, the pump is ran at the maximum speed.
• a detection whether the pump is clogged is performed; and if it is detected that the pump is clogged, the pump is ran reversely at a predetermined speed during a period of time having a predetermined length, it is then stopped and ran at the normal direction. Moreover, the step of running the pump impeller reversely, stopping it and change the operating direction is repeated until it is detected that the clogging condition has ceased.
• this embodiment provides for a an efficient way of operating a VFD pump in respect of power consumption and durability since the wear of, especially, the pump impeller is reduced. Moreover, since the clogging condition can be removed in an efficient way the power consumption of the pump can also be reduced.
• the method according to the present invention are suitable to realize or implement as a computer program or a computer readable medium, preferably within the contents of a control device or a processing means of a pump or a pump system.
• Fig. 1 schematically shows an embodiment of a pump according to the present invention
• FIG. 2 schematically shows an embodiment of a pump system according to the present invention
• Fig. 3 shows a pump curves for a conventional pump and a pump operated in accordance with the present invention
• Fig. 4 shows the principles of a method of an embodiment according to the present invention
• Fig. 5 shows the principles of a method of another embodiment according to the present invention.
• Fig. 6 shows the principles of a method of yet another embodiment according to the present invention.
• Fig. 7 schematically shows a further embodiment of a pump and a control device for such a pump according to the present invention
• Fig. 8 schematically shows another embodiment of a pump and a control device for such a pump according to the present invention.
• FIG. 9 schematically shows yet another embodiment of a pump and pump
• a first embodiment of a pump according to the present invention will be described.
• the embodiments of the present invention described hereinafter are utilized in submersible VFD-pumps.
• the present invention can also be utilized in other types of pumps, such as sewage pumps, drainage pumps, and de-watering pumps.
• the submersible pump 1 of Fig. 1 comprises a variable-speed unit 2, preferably a variable frequency drive unit (VFD unit) connected via a connection cable 3 to a power source (not shown) delivering, for example, a single phase voltage or a three phase voltage.
• the VFD unit 2 comprises an electro-magnet interference filter 4 (EMI filter) arranged at the connection cable 3 in order to filter out electro-magnet interference at the input.
• a rectifier 5 is connected to the EMI filter 4 connected via a DC link 10, in turn, including a capacitor 6 a transducer 7.
• the transducer 7 converts the DC current to a three-phase current, which is supplied to a pump motor 9 via a connection 8.
• the function and components and parts of a VFD unit is well- known for the man skilled within the art and hence they will not be described in further detail herein.
• Control device 11 is arranged in communication with the VFD unit 2 via a communication bus (not shown) and controls or drives the pump 1 to, for example, increase or decrease the speed in order to pump a larger or a smaller amount of fluid, for example, water. Furthermore, the control device 11 is capable of obtaining signals corresponding to the measurements of operating parameters, for example the DC power of the DC link 10 or the torque of the motor.
• the control device 11 is, in turn, controlled by processing means 12, which includes storing means 13.
• the storing means 13 may include a random access memory (RAM) and/ or a non-volatile memory such as read- only memory (ROM).
• the storing means 13 comprises a computer program 14 comprising instructions for bringing a computer or a microprocessor, such as the processing means 12, to cause method steps in accordance with the present invention.
• storing means may include various types of physical devices for temporary and/ or persistent storage of data which includes solid state, magnetic, optical and combination devices.
• the storing means may be implemented using one or more physical devices such as DRAM, PROMS, EPROMS, EEPROMS, flash memory, and the like.
• the control device 11 is arranged in communication via an interface unit (not shown) with an operator unit 22 including input means in the form of a keyboard 24, which allows the operator to input, for example, control commands, and a display means or screen 26 for presenting information related operation of the pump, for example, time history of the operating parameters, or status information of the pump.
• the operator unit 22 is a personal computer.
• the communication link between the pump 1 and the operator unit 22 can be a wireless link or a hard wired link.
• the operator unit 22 can, in turn, be connected to a communications network, such as the Internet.
• the operator unit 22 By means of the operator unit 22, the operator is capable of monitoring the operation of the pump as well as different operating parameters associated to the operation thereof via the display 26.
• the display is a touch sensitive screen and in this case a number of soft-keys can be arranged on the screen in order to present different commands at different presented interfaces on the display 26.
• the operator unit may comprise storing means (not shown), which, in turn, may include a random access memory (RAM) and/or a non-volatile memory such as read-only memory (ROM).
• RAM random access memory
• ROM read-only memory
• storing means may include various types of physical devices for temporary and/ or persistent storage of data which includes solid state, magnetic, optical and combination devices.
• the storing means may be implemented using one or more physical devices such as DRAM, PROMS, EPROMS, EEPROMS, flash memory, and the like.
• Running data of the pump 1, such as operating parameters like running time, number of starts, power consumption, and alarm data, as well as service record can be obtained and stored in a logging file in the storing means 13.
• the logging file can be presented for an operator by means of the operator unit 22.
• the logging file can be downloaded to the operator unit 22 for, e.g. storage.
• control device 11 can be realized by means of a processor including, inter alia, programmable instructions for executing the methods according to the present invention.
• the control device is implemented in the form of a micro-chip or the like data carrier comprising software adapted to execute the functions described above and hereinafter.
• Figs. 7-9 alternative embodiments of the present invention axe shown. Like or similar parts and/ or devices in Figs. 1,2 and 7-9 are being denoted with the same reference numerals.
• the control device 11 which may be encapsulated in a hermetically sealed housing, is arranged on an outer surface of the pump housing.
• the control device 11 can be attached or fixed at the housing in a number of ways.
• the device 11 can be fixed by means of screws.
• the control device 11 is in form of a plug-in unit adapted to inserted in a control device receiving recess 15.
• the control device 11 is arranged in the control panel 22.
• This first aspect of the method according to invention deals with the snoring operation problem or the dry-run operation problem, which, as discussed above, entails increased wear of pump part such as the impeller and the seals, may cause the pump motor to overheat and also leads to that unnecessary power is consumed.
• pump motors are designed to provide optimum performance when they are pumping and operating in fluid, so ⁇ . ⁇ prolonged dry-run operation can damage the pump motor.
• the first aspect of the invention provides for a an efficient way of operating a VFD pump as described with reference to any one of Figs. 1-2 and 7-9 in respect of power consumption, pump life, and durability.
• the operation of the pump is initiated, i.e. the pump is started.
• the pump is ran at a first low speed level and at a second low speed level.
• step 44 If, in step 44, it is determined that the fluid level is not sufficient, the algorithm proceeds to step 46, where the control device 11 sends an instruction to the VFD unit 2 to pause the operation of the pump is during a predetermined period of time, for example, a number of minutes, maybe about 2 minutes. When this period of time has expired, the algorithm returns to step 42.
• a predetermined period of time for example, a number of minutes, maybe about 2 minutes.
• step 44 determines that the fluid level is sufficient
• the algorithm proceeds to step 48, where the speed of the pump is increased to full speed.
• the pump is now operated in a normal manner.
• step 50 it is checked whether the fluid level still is sufficient, i.e. whether the pump sucks air partly or mainly of if it is pumping fluid. This is performed on a substantially continuous basis.
• an operating parameter is obtained by the control device 11.
• the DC link power, the current or the torque of the motor can be used.
• the DC link power is used.
• the DC link power is compared with a predetermined power level, which may be stored in the storing means 13, and if the DC link power level is lower than the predetermined level, it is determined that the fluid level is too low.
• a predetermined power level may be about 70 % of the maximum DC power.
• step 48 If it is determined that the fluid level at the inlet of the pump is sufficient, i.e. the DC link power is higher than the predetermined level, the algorithm returns to step 48. On the other hand, if it is determined that the fluid level at the inlet of the pump is too low, i.e. the DC link power is lower than the predetermined level, the algorithm instead proceeds to step 52, where the operation of the pump is stopped. Subsequently, the algorithm proceeds to step 46, where the operation of the pump is stopped during a predetermined period of time. When this pause period has expired, the algorithm proceeds to further on to step 42. With reference now to Fig. 5, the general principles of the method for operating a pump according to a second aspect of the present invention will be described.
• This second aspect of the method according to invention deals with the problem of maintaining the power of the pump over a large range of flows.
• the pump head/pressure can be increased by 20% to 30% by means of the method according to the second aspect. Due to the fact that the pump is operated more efficient at low flows a smaller pump can be used to pump a given amount of liquid, and the wear of the pump can also be reduced.
• the second aspect of the invention provides for a an efficient way of operating a VFD pump as described with reference to any one of Figs. 1-2 and 7-9 in respect of power consumption and durability.
• step 60 the operation of the pump is initiated, i.e. the pump is started.
• step 62 the pump is ran at full speed.
• a operating parameter of the pump is monitored substantially continuously and values corresponding to the parameter is obtained by the control device 11 and compared with a predetermined parameter level at step 64.
• the DC link power, the current or the torque of the motor can be used.
• the DC link power is used and compared with the rated power of the pump motor, which may be stored in the storing means 13, in, for example the processing means 12. If, at step 64, it is determined that the DC link power level is higher than the predetermined level, the algorithm returns to step 62, and the operation of the pump is maintained at full speed. On the other hand, if it is determined that the DC link power level is lower than the predetermined level, the algorithm proceeds to step 66, where the speed required to reach the predetermined power level is calculated in the processing means 12.
• step 68 the calculated speed is compared with the maximum speed. If the calculated speed is found to be higher than the maximum speed, the algorithm proceeds to step 70, where the control device 11 sends an instruction to the VFD unit 2 to run the motor at maximum speed, and the algorithm returns to step 64. If it is found that the calculated speed is lower than the maximum speed, the algorithm proceeds to step 72 and the control device 11 sends an instruction to the VFD unit 2 to run the motor at the calculated speed. Thereafter, the algorithm proceeds to step 64 where the procedure is continued. By maintaining the power at a substantially constant level, the head/pressure can be increased at low flows as indicated by means of line 32 in fig. 3.
• This third aspect of the method according to invention deals with the problem of clogging or jam of the intake and/ or impeller, which may be caused by particles in the fluid that sediment at the intake and in the impeller and build silt having a relatively thick or solid consistency.
• a large starting torque of the pump motor is required in order to initiate the rotating of the pump impeller. This consumes large amounts of energy and also wears the pump impeller and the motor.
• the third aspect of the invention provides for a an efficient way of operating a VFD pump as described with reference to any one of Figs. 1-2 and 7-9 in respect of power consumption, durability and starting reliability.
• step 80 the operation of the pump is initiated, i.e. the pump is started. Then, at step 82, the pump is ran at full speed. Thereafter, at step 84, a check is performed whether the pump is clogged/jammed. This can be performed in two ways. One way is to measure an operating parameter of the pump and compare it with a predetermined level, for example, measure the
• the second way is to monitor the alarm function of the variable frequency unit 2 and an alarm indicating over-current is used as an indication of a clogged/jammed condition.
• step 84 If it, in step 84, is determined that the pump is not clogged, the algorithm returns to step 82, where the operation of the pump is maintained. On the other hand, if it is determined that the pump is clogged, the algorithm proceeds to step 86, where the control device 11 sends an instruction to the VFD unit 2 to drive the impeller reversely at full speed during a predetermined period of time, it is stopped and then ran in a forward rotating direction again. Preferably, such a cycle lasts about 1-10 seconds. Then, at step 88, it is checked whether the clogging state has ceased. If not, the procedure returns to step 86. This cycle is repeated until the clogging condition has been removed. If the clogging state has ceased, the algorithm returns to step 82.
• the following procedure can be performed at regular intervals: running the pump 1 reversely at a predetermined speed during a period of time having a predetermined length, stopping the pump 1 after said period and running the pump 1 at its normal rotation direction. Thereby, the operation reliability of the pump can be improved.

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• 2005
  • 2005-06-21 WO PCT/EP2005/052878 patent/WO2006136202A1/en active Application Filing
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