WO2009151680A2 - Cable loss compensation in an electrical submersible pump system - Google Patents

Cable loss compensation in an electrical submersible pump system Download PDF

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Publication number
WO2009151680A2
WO2009151680A2 PCT/US2009/036873 US2009036873W WO2009151680A2 WO 2009151680 A2 WO2009151680 A2 WO 2009151680A2 US 2009036873 W US2009036873 W US 2009036873W WO 2009151680 A2 WO2009151680 A2 WO 2009151680A2
Authority
WO
WIPO (PCT)
Prior art keywords
cable
power source
motor
current
voltage
Prior art date
Application number
PCT/US2009/036873
Other languages
English (en)
French (fr)
Other versions
WO2009151680A3 (en
Inventor
Tom G. Yohanan
Dick L. Knox
John M. Leuthen
Jim E. Layton
Howard G. Thompson
Original Assignee
Baker Hughes Incorporated
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Baker Hughes Incorporated filed Critical Baker Hughes Incorporated
Priority to BRPI0909176-9A priority Critical patent/BRPI0909176B1/pt
Priority to EP09762976.0A priority patent/EP2255066B1/en
Priority to AU2009258025A priority patent/AU2009258025C1/en
Publication of WO2009151680A2 publication Critical patent/WO2009151680A2/en
Publication of WO2009151680A3 publication Critical patent/WO2009151680A3/en

Links

Classifications

    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B47/00—Survey of boreholes or wells
    • E21B47/008—Monitoring of down-hole pump systems, e.g. for the detection of "pumped-off" conditions
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
    • E21B43/12—Methods or apparatus for controlling the flow of the obtained fluid to or in wells
    • E21B43/121—Lifting well fluids
    • E21B43/128—Adaptation of pump systems with down-hole electric drives
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P23/00—Arrangements or methods for the control of AC motors characterised by a control method other than vector control
    • H02P23/08—Controlling based on slip frequency, e.g. adding slip frequency and speed proportional frequency
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
    • H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
    • H02P27/047—V/F converter, wherein the voltage is controlled proportionally with the frequency

Definitions

  • the present invention relates in general to electrical submersible pump (ESP) systems and, in particular, to an improved system, method, and program product for controlling motor terminal voltage under varying load conditions by compensating for cable loss.
  • ESP electrical submersible pump
  • ESP Background Electrical submersible pumping
  • wellbore includes oil wells, gas wells, geothermal wells, carbon sequestration wells, and others as understood by those skilled in the art.
  • a typical ESP system includes a centrifugal pump which is driven by a three-phase AC motor, both located in the wellbore, and a variable speed drive which delivers three-phase power to the motor, located at the surface. Connecting the motor to the variable speed drive is a cable. Because the motor can be a very long distance from the variable speed drive, the voltage drop in the cable is very significant.
  • the output voltage of the variable speed drive is set to produce rated voltage at the motor terminals when the motor is operating at or near ratings. The output voltage of the variable speed drive is then varied linearly with the operating frequency to maintain a constant V/Hz ratio at the terminals of the variable speed drive.
  • Varying the output voltage of the variable speed drive linearly with operating frequency has a known problem. For example, if the operating speed of the motor is decreased for any reason, the load on the motor decreases because the pump load is a function of the revolutions per minute. A decreased load on the motor results in a lower motor current, which in turn decreases the voltage drop in the cable. Because the motor can be a very long distance from the variable speed drive, a decreased voltage drop in the cable is very significant. The end result is that the motor terminal voltage is too high, which can cause extra heating of the motor, decreased efficiency, and saturation of the core leading to other problems, as understood by those skilled in the art.
  • V/HZ curve a "shaped" V/Hz curve.
  • the "shaped" V/Hz curve may be a piecewise continuous curve, or similar curve as understood by those skilled in the art, based on the expected motor load for a centrifugal pump.
  • the approaches of the prior art are not responsive to all changes in well conditions. For example, the motor load can change even at a constant RPM due to well conditions.
  • varying the output voltage of the variable speed drive with the operating frequency according to either a linear or "shaped" V/Hz curve fails to provide the proper rated motor voltage because the frequency, that is, the RPM, is constant and under the prior art the voltage from the variable speed drive is maintained, despite the motor load changing.
  • the proper rated motor voltage is only "proper" at rated load.
  • embodiments of the present invention provide a method, system, and program product to control voltage at the motor terminals under varying conditions by actively modifying the output voltage of the variable speed drive to compensate for cable loss in the ESP system.
  • Embodiments of the present invention advantageously utilize algorithms to optimize output voltage of the variable speed drive in an ESP system, which include compensating for cable loss using the motor current and the complex impedance of the cable.
  • Figure 1 is a schematic side view of an embodiment of an electrical submersible pump system in accordance with the present invention
  • Figure 2 is a method of operating an electrical submersible pumping system according to an embodiment of the present invention
  • Figure 3 is a schematic diagram of a program product associated with an electrical submersible pumping system according to an embodiment of the present invention
  • Figure 4 is an exemplary graph of surface voltage versus motor frequency for an example according to the prior art and an example according to an embodiment of the present invention
  • Figure 5 is an exemplary graph of surface power versus motor frequency for an example according to the prior art and an example according to an embodiment of the present invention
  • Figure 6 is an exemplary graph of motor voltage versus motor frequency for an example according to the prior art and an example according to an embodiment of the present invention
  • Figure 7 is an exemplary graph of motor input power versus motor frequency for an example according to the prior art and an example according to an embodiment of the present invention.
  • Figure 8 is an exemplary graph of motor current versus motor frequency for an example according to the prior art and an example according to an embodiment of the present invention.
  • Embodiments of the present invention provide a more accurate approach for controlling a motor terminal voltage in an ESP system and actively modifying the output voltage of the surface variable speed drive. Under existing approaches, voltage drop in the cable is not compensated for accurately. Under embodiments of the present invention, the voltage drop in the cable is calculated and directly compensated for as part of actively modifying the output voltage of the surface variable speed drive. Benefits of the embodiments of the present invention include improve efficiency and improved system performance.
  • one type of electrical submersible pump (ESP) system 30 includes a centrifugal pump 22, a motor 26, and a seal assembly 24 located between the pump 22 and motor 26.
  • the ESP system 30 is located with a wellbore 28.
  • the ESP system 30 further includes a variable speed drive 20 and controller 36 located on the surface 38 and associated with the variable speed drive 20.
  • An ESP system often includes a step-up transformer 33, located between the variable speed drive 20 and a cable 32.
  • the cable 32 provides power, e.g., three-phase power, and communications between the variable speed drive 20 and the motor 26.
  • the variable speed drive 20 may operate as a power source for providing electrical power for driving the motor 26.
  • the cable 32 typically extends thousands of feet and thereby introduces significant electrical impedance between the variable speed drive 20 (or step-up transformer 33) and the motor 26.
  • the controller 36 associated with the variable speed drive 20 controls the voltage at motor 26 terminals.
  • the cable 32 connects to a motor lead extension (not shown) proximate to the pumping system.
  • the motor lead extension continues in the wellbore 28 adjacent the system 34 and terminates in what is commonly referred to as a "pothead connection" at the motor 26.
  • the motor terminal comprises the pothead connection.
  • an embodiment of the present invention includes a method 50 of controlling voltage supplied to an electrical submersible pumping system.
  • the method includes providing an electrical submersible pumping system pump and motor in a wellbore (step 51) and powering the motor with a power source that is connected to the motor with a cable (step 52).
  • the method also includes determining an impedance of a cable in an electrical submersible pumping system (step 53).
  • the impedance of the cable can be determined through a measurement as understood by those skilled in the art. Alternately, the impedance of the cable can be calculated from the length of the cable.
  • the cable is connected between a downhole motor and a surface variable speed drive and delivers power, e.g., three- phase power, from the surface to the downhole motor.
  • the method also includes determining a current in the cable (step 54), including a three-phase current.
  • a current in the cable Li an embodiment of an ESP system without a step up transformer, a direct measurement of the current in the cable can occur at the output of the drive, or elsewhere with access to the cable as understood by those skilled in the art.
  • the current is the cable can be determined from measurements of the current at the output of the drive and a calculation that takes into account the transformer.
  • the method further includes calculating a voltage drop associated with the cable (step 55).
  • Motor operation may fluctuate due to variations in fluid properties and conditions, such as, density, viscosity, fluid phase, temperature, and pressure, to name but a few. This fluctuation may affect the motor current consumption, which in turn causes a corresponding change in the cable voltage drop.
  • the voltage drop associated with the cable is the product of the cable impedance and current in the cable.
  • One embodiment of the present method further includes continued or periodic monitoring of the current in the cable. Also included is continued or periodic cable voltage drop evaluation.
  • the method also includes controlling the output of a power source, such as a surface variable speed drive, in response to the aforementioned fluctuations in cable current, cable voltage drop, or combinations thereof.
  • Controlling the power source output involves regulating or adjusting the voltage output.
  • the power supply output is modified to control a motor terminal voltage by compensating for the voltage drop associated with the cable (step 56). That is, the method directly compensates for the voltage drop associated with the cable to control the output of the variable speed drive.
  • the control method employed may comprise simple feedback, linear, proportional, or any other control scheme.
  • the method can include controlling the power source output voltage based on the calculated voltage drop to optimize a voltage to the motor.
  • One simple optimization approach can include adjusting the power source output voltage for minimum current to maintain the proper voltage to the motor according to an embodiment of the present invention. While an improvement over the prior art, this approach may not yield the best efficiency, hi a second optimization embodiment, shaft speed is controlled by compensating for changing slip with changing frequency, while adjusting the output voltage to obtain minimum current according to an embodiment of the present invention. This second approach may require more processing power, but may better optimize system efficiency.
  • inventions of the present invention provide benefits and advantages.
  • Features of the embodiments of the present invention include an improved responsiveness to varying motor load conditions and the ability to control voltage at the motor terminals by directly compensating for voltage loss in the cable.
  • the benefits of the embodiments of the present invention include preventing extra heating of the motor, decreased efficiency, and saturation of the core leading to other problems as understood by those skilled in the art. Still other advantages include reduction in overall product lifecycle cost and improved efficiency.
  • an embodiment of the present invention includes a program product stored in a tangible computer medium that when executed by a computer performs various operations.
  • the operations include determining an impedance of a cable in an electrical submersible pumping system (block 64) and determining a current in the cable (block 65).
  • the current in the cable can be determined directly by measurements from a current sensor at the variable speed drive in an embodiment of an ESP system with out a step- up transformer.
  • the current in the cable can be determined from measurements from a current sensor at the variable speed drive and a calculation that takes into account the transformer in an embodiment of an ESP system with a step-up transformer.
  • the operations also include calculating a voltage drop associated with the cable (block 66).
  • the voltage drop associated with the cable is the product of the impedance of the cable and the current in the cable.
  • the operations further include modifying an output voltage of the surface variable speed drive to control a motor terminal voltage by compensating for the voltage drop associated with the cable (block 67). That is, the controller can calculate the voltage drop associated with the cable and directly compensate for this voltage drop, to control the output of the variable speed drive.
  • another program product embodiment of the present invention includes modifying an output voltage and frequency of the surface variable speed drive to optimize the voltage to the downhole motor.
  • One optimization includes adjusting the power source output voltage to provide a minimum current in the cable that maintains a proper motor voltage, that is, the manufacturer's rated voltage for the motor load, according to an embodiment of the present invention.
  • Another optimization approach includes controlling the shaft speed by compensating for changing slip, or other varying wellbore conditions, with changing frequency, while adjusting the output voltage to provide a minimum current that maintains a proper motor voltage according to an embodiment of the present invention. That is, the motor shaft speed is controlled by changing a power source output voltage frequency to thereby compensate for changing slip and the power source output voltage is adjusted to minimize the load current, while maintaining a minimum motor voltage so that the motor operates within the manufacturer's specifications.
  • Figures 4 - 8 provide resulting data for an example according to an embodiment of the present invention contrasted with an example according to the prior art.
  • These examples of an ESP system include a 342-horsepower 1695-volt motor, a 342 horsepower pump load at 60 Hz, and 10,000 feet of cable.
  • the load on the motor decreases because the pump load is a function of the revolutions per minute.
  • a decreased load on the motor results in a lower motor current, which in turn decreases the voltage drop in the cable.
  • the output voltage of the variable speed drive, or the surface voltage is varied linearly with operating frequency of the motor.
  • the data corresponding to the example according to the prior art is shown by a dotted line 81, 86, 91, 96, 101 in the various graphs.
  • the voltage drop associated with the cable is calculated so that the output voltage of the variable speed drive, or the surface voltage, is controlled responsive to the voltage drop associated with the cable.
  • the data corresponding to the example according to the embodiment of the present solution is shown by a solid line 82, 87, 92, 97, 102 in the various graphs.
  • Figure 4 is an exemplary graph of surface voltage versus motor frequency 80, illustrating data for the example according to an embodiment of the present invention in the solid line 82 contrasted with data for the example according to the prior art in the dotted line 81.
  • Figure 5 is an exemplary graph of surface power (KVA) versus motor frequency 85, illustrating data for the example according to an embodiment of the present invention in the solid line 87 contrasted with data for the example according to the prior art in the dotted line 86.
  • Figure 6 is an exemplary graph of motor voltage versus motor frequency 90, illustrating data for the example according to an embodiment of the present invention in the solid line 92 contrasted with data for the example according to the prior art in the dotted line 91.
  • Figure 7 is an exemplary graph of motor input power (KVA) versus motor frequency 95, illustrating data for the example according to an embodiment of the present invention in the solid line 97 contrasted with data for the example according to the prior art in the dotted line 96.
  • Figure 8 is an exemplary graph of motor current versus motor frequency 100, illustrating data for the example according to an embodiment of the present invention in the solid line 102 contrasted with data for the example according to the prior art in the dotted line 101.
  • the benefits of the embodiments of the present invention include increased efficiency through a reduction in surface voltage over a range of frequencies (see especially Figure 4), the preventing extra heating of the motor through a reduction in motor voltage (see especially Figure 6), and the decrease in power loss in the cable through a reduction in motor current (see especially Figure 8).
  • Examples of computer readable media include but are not limited to: nonvolatile, hard-coded type media such as read only memories (ROMs), CD-ROMs, and DVD-ROMs, or erasable, electrically programmable read only memories (EEPROMs), recordable type media such as floppy disks, hard disk drives, CD-R/RWs, DVD-RAMs, DVD-R/RWs, DVD+R/RWs, flash drives, and other newer types of memories, and transmission type media such as digital and analog communication links.
  • ROMs read only memories
  • CD-ROMs compact discs
  • DVD-RAMs digital versatile disk drives
  • DVD-R/RWs digital versatile disks
  • DVD+R/RWs DVD+R/RWs
  • flash drives and other newer types of memories
  • transmission type media such as digital and analog communication links.
  • such media can include both operating instructions and/or instructions related to the system and the method steps described above.

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  • Engineering & Computer Science (AREA)
  • Geology (AREA)
  • Mining & Mineral Resources (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Physics & Mathematics (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Fluid Mechanics (AREA)
  • Environmental & Geological Engineering (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Geophysics (AREA)
  • Power Engineering (AREA)
  • Control Of Non-Positive-Displacement Pumps (AREA)
  • Control Of Ac Motors In General (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)
PCT/US2009/036873 2008-03-12 2009-03-12 Cable loss compensation in an electrical submersible pump system WO2009151680A2 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
BRPI0909176-9A BRPI0909176B1 (pt) 2008-03-12 2009-03-12 Sistema de bombeamento submersível elétrico e método de operar tal sistema
EP09762976.0A EP2255066B1 (en) 2008-03-12 2009-03-12 Cable loss compensation in an electrical submersible pump system
AU2009258025A AU2009258025C1 (en) 2008-03-12 2009-03-12 System, method and program product for cable loss compensation in an electrical submersible pump system

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US3576408P 2008-03-12 2008-03-12
US61/035,764 2008-03-12
US19193109A 2009-03-09 2009-03-09
US12/191,931 2009-03-09

Publications (2)

Publication Number Publication Date
WO2009151680A2 true WO2009151680A2 (en) 2009-12-17
WO2009151680A3 WO2009151680A3 (en) 2010-04-22

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PCT/US2009/036873 WO2009151680A2 (en) 2008-03-12 2009-03-12 Cable loss compensation in an electrical submersible pump system

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AU (1) AU2009258025C1 (pt)
BR (1) BRPI0909176B1 (pt)
WO (1) WO2009151680A2 (pt)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NO20150973A1 (en) * 2015-07-10 2017-01-11 Aker Subsea As Subsea pump and system and methods for control
WO2017010891A1 (en) * 2015-07-10 2017-01-19 Aker Subsea As Subsea pump and system and methods for control
WO2017030701A1 (en) * 2015-08-18 2017-02-23 Baker Hughes Incorporated Systems and methods for providing power and communications for downhole tools
WO2021248155A1 (en) * 2020-06-03 2021-12-09 Baker Hughes Oilfield Operations Llc Motor current balancing method for esp system
CN114844437A (zh) * 2022-06-08 2022-08-02 青岛海洋工程水下设备检测有限公司 电机控制系统及海底动力系统

Citations (1)

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Publication number Priority date Publication date Assignee Title
US20040064292A1 (en) 2002-09-27 2004-04-01 Beck Thomas L. Control system for centrifugal pumps

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US6045333A (en) * 1997-12-01 2000-04-04 Camco International, Inc. Method and apparatus for controlling a submergible pumping system
DE19840479A1 (de) * 1998-09-04 2000-03-09 Wilo Gmbh Strommessung in Pumpen
ES2234794T3 (es) * 2001-07-16 2005-07-01 Axa Power A/S Compensacion de la caida de tension del cable en un sistema de alimentacion de energia electrica.
US6522119B1 (en) * 2001-09-11 2003-02-18 Schlumberger Technology Corporation Power source regulator for wireline cable system
US7170262B2 (en) * 2003-12-24 2007-01-30 Foundation Enterprises Ltd. Variable frequency power system and method of use
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Publication number Priority date Publication date Assignee Title
US20040064292A1 (en) 2002-09-27 2004-04-01 Beck Thomas L. Control system for centrifugal pumps

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NO20150973A1 (en) * 2015-07-10 2017-01-11 Aker Subsea As Subsea pump and system and methods for control
WO2017010891A1 (en) * 2015-07-10 2017-01-19 Aker Subsea As Subsea pump and system and methods for control
NO339736B1 (en) * 2015-07-10 2017-01-30 Aker Subsea As Subsea pump and system and methods for control
GB2557482A (en) * 2015-07-10 2018-06-20 Aker Solutions As Subsea pump and system and methods of control
WO2017030701A1 (en) * 2015-08-18 2017-02-23 Baker Hughes Incorporated Systems and methods for providing power and communications for downhole tools
GB2557782A (en) * 2015-08-18 2018-06-27 Baker Hughes A Ge Co Llc Systems and methods for providing power and communications for downhole tools
GB2557782B (en) * 2015-08-18 2021-09-01 Baker Hughes A Ge Co Llc Systems and methods for providing power and communications for downhole tools
WO2021248155A1 (en) * 2020-06-03 2021-12-09 Baker Hughes Oilfield Operations Llc Motor current balancing method for esp system
WO2021247762A1 (en) * 2020-06-03 2021-12-09 Baker Hughes Oilfield Operations, Llc Motor current balancing method for esp system
US11368119B2 (en) 2020-06-03 2022-06-21 Baker Hughes Oilfield Operations Llc Motor current balancing method for ESP system
CN114844437A (zh) * 2022-06-08 2022-08-02 青岛海洋工程水下设备检测有限公司 电机控制系统及海底动力系统

Also Published As

Publication number Publication date
AU2009258025A1 (en) 2009-12-17
BRPI0909176A2 (pt) 2018-07-31
AU2009258025C1 (en) 2013-11-28
AU2009258025B2 (en) 2013-07-04
BRPI0909176B1 (pt) 2019-03-26
WO2009151680A3 (en) 2010-04-22

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