AU2021107635B4

AU2021107635B4 - Hybrid generator

Info

Publication number: AU2021107635B4
Application number: AU2021107635A
Authority: AU
Inventors: Jonathan Florent Douce; Ravi Jain
Original assignee: Trent Bridge VIC Engineering Pty Ltd
Current assignee: Trent Bridge VIC Engineering Pty Ltd
Priority date: 2019-12-19
Filing date: 2021-12-04
Publication date: 2022-04-14
Anticipated expiration: 2028-12-19
Also published as: AU2021201656A1; AU2022100192A4; AU2022287680A1; AU2021107641A4; AU2021107650A4; AU2021107635A4; AU2022100063A4; AU2021107650B4

Abstract

A system configured to supply electrical power to an electric submersible pump comprises a portable generator assembly comprising an engine and an alternator, wherein the alternator is mechanically coupled to the engine to generate an alternating current for powering the pump. The alternator comprises a voltage regulator operatively configured to control a voltage of the alternating current. The engine comprises a throttle controller to control a rotational speed of the engine and, therefore, frequency of the alternating current. The system also comprises at least one renewable power generator system for powering the pump. A control system varies the frequency and voltage of the alternating current by controlling, respectively, the throttle controller and voltage regulator based on levels of electrical power generated, or capable of being generated, by the renewable power generator system.

Description

HYBRID GENERATOR

Field

[0001] The present invention relates to electrical power generation and, more particularly, to a hybrid generator system configured to supply electrical power to one or more electric submersible pumps.

Background

[0002] A variety of mechanical devices and machines operated by electric motors are often used in remote locations in industry. For example, electric submersible pumps (ESPs), which commonly contain alternating current (AC) induction motors, are frequently used to pump groundwater in mining and construction projects. When a grid-based supply of electricity is not available to power such pumps, electricity must be created and supplied locally using an electric generator. An electric generator typically comprises a prime mover, such as an internal combustion engine or gas turbine, mechanically coupled to an alternator that produces AC power.

[0003] Electric generators consume substantial quantities of fuel, such as diesel or natural gas, which is expensive to procure and transport. If electric power for a construction project is only available from fossil fuel-based generators, then the running of these generators may constitute a substantial operating expense of the project. Further, if the fuel supply is restricted for any reason then this may result in project downtime and delay.

[0004] Fossil fuel-based generators are also environmentally unfriendly. Renewable energy generators, such as solar generators, may be used to power an ESP but only when the weather or relevant environmental conditions are favorable. If the renewable generator is only capable of supplying some, but not all, of the power necessary to operate the ESP, then the generator is redundant and a fossil fuel-based generator must be used instead. Swapping between renewable and non-renewable generators is time consuming and does not allow ESPs to be powered and controlled continuously in an efficient manner.

[0005] The preceding discussion of the background is intended to facilitate an understanding of the present invention only. The discussion is not an acknowledgement or admission that any of the material referred to is or was part of the common general knowledge as at the priority date of the present application.

Summary

[0006] According to the present invention, there is provided a system configured to supply electrical power to an electric submersible pump, the system comprising: a portable generator assembly comprising an engine and an alternator mechanically coupled to the engine to generate an alternating current for powering the pump, wherein the alternator comprises a voltage regulator operatively configured to control a voltage of the alternating current, and wherein the engine comprises a throttle controller to control a rotational speed of the engine and, therefore, frequency of the alternating current; at least one renewable power generator system for powering the pump; and a control system configured to vary the frequency and the voltage of the alternating current by controlling, respectively, the throttle controller and the voltage regulator based on levels of electrical power generated, or capable of being generated, by the renewable power generator system.

[0007] The control system may include a control mode wherein electric power supplied to the pump is generated by both the portable generator assembly and the renewable power generator system simultaneously.

[0008] The control system may include a control mode wherein electric power supplied to the pump is generated by either only the portable generator assembly or only the renewable power generator system selectively.

[0009] The renewable power generator system may comprise at least one battery for storing electrical power produced by the renewable power generator system and the control system may include a control mode wherein electrical power stored in the battery is supplied to the pump.

[0010] The renewable power generator system may comprise one or more solar cells connected to an inverter to generate a second alternating current for powering the pump.

Brief Description of Drawings

[0011] Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which: Figure 1 is a schematic diagram of a system configured to supply electrical power to an electric submersible pump according to an example embodiment of the invention; and Figure 2 is a schematic diagram of a system configured to supply electrical power to an electric submersible pump according to a further example embodiment of the invention.

Description of Embodiments

[0012] Referring to Figure 1, an example embodiment of the present invention provides a system 10 configured to supply electrical power to an electric submersible pump (ESP) 12. The system 10 comprises a portable generator assembly 14 comprising an engine 16 and an alternator 18, wherein the alternator 18 is mechanically coupled to the engine 16 to generate an alternating current for powering the pump 12. The alternator 18 comprises a voltage regulator 20 operatively configured to control a voltage of the alternating current. The engine 16 comprises a throttle controller 22 to control a rotational speed of the engine 16 and, therefore, frequency of the alternating current. The system 10 also comprises at least one renewable power generator system 24 for powering the pump 12. A control system 26 is configured to vary the frequency and the voltage of the alternating current produced by the alternator 18 by controlling, respectively, the throttle controller 22 and the voltage regulator 20 based on levels of electrical power generated, or capable of being generated, by the renewable power generator system 24.

[0013] More particularly, the generator assembly 14 and renewable power generator system 24 may produce first and second alternating currents respectively. The renewable power generator system 24 may comprise a variable speed drive (VSD) 28 that receives an AC current from a renewable DC generator 30 and inverter 32 combination. The VSD 28 uses the received AC current to generate and supply the second alternating current to the ESP 12 at a required frequency and voltage. The VSD 28 may comprise a pulse width modulation (PWM) circuit with the following internal components (not shown): (i) an AC to DC rectifier for converting the AC current received from the inverter 32 into an unfiltered direct current, (ii) a filter for transforming the unfiltered direct current into a smoothed/filtered direct current and (iii) a DC to AC inverter for converting the smoothed/filtered direct current back into an alternating current that is output from the VSD 28 and supplied to the pump 12. The rectifier may comprise a diode bridge circuit and the filter may comprise a capacitor bank. The inverter may comprise transistors that are configured to implement a PWM process that outputs the alternating current from the VSD 28 at a particular frequency and voltage as determined by the control system 26.

[0014] The throttle controller 22 of the generator assembly 14 may comprise an actuated governor or, as depicted in FIG. 1, an engine control unit (ECU) 22 that controls electrically the fuel supplied to the engine 16 to control the speed of the engine 16. The control system 26 may send control signals to the ECU 22 to vary the speed of the engine 16 and, consequently, the frequency of the first alternating current generated by the alternator 18. The AC voltage regulator 20 may comprise an excitation controller or system provided with field coils. An excitation current, typically a direct current, flowing through the field coils determines the voltage of the alternating current that is generated by the alternator 18. The voltage regulator 20 may be operatively configured to receive control signals from the control system 26 and then control the excitation current on an automatic basis so that the first alternating current output from the alternator 18 has the required voltage. In this configuration, the control system 26 uses the throttle control and voltage regulator 20, together, to control the frequency and voltage of the first alternating current used to power the pump 12 and, therefore, to control the operating speed of the pump 12.

[0015] The renewable generator system 24 may comprise a variety of different devices and components for producing its own electric power independently of the generator assembly 14. In the example depicted, the renewable generator system 24 comprises a direct current (DC) generator system 30 that is connected to an inverter 32. Preferably, the DC generator system 30 comprises a solar generator, wind turbine or other renewable energy source.

[0016] The inverter 32 converts DC electricity produced by the renewable DC generator into AC electricity that is supplied to the VSD 28. The renewable generator system 24 may also comprise at least one battery 34 that is charged by the renewable DC generator 30. Electrical power stored in the battery 34 may be used to supply DC power to the inverter 32 when the control system 26 determines that the DC generator 30 is incapable of supplying sufficient power to the pump 12.

[0017] The control system 26 may comprise a processor, a programmable logic controller (PLC), a programmable logic array (PLA) or similar electronic controller device. The control system 26 may comprise a single integrated electronic controller device or multiple controller devices (including multiple processors or PLAs) connected together via a network, buses or similar communication system. In examples where the control system 26 comprises a processor, the processor may be a device capable of executing instructions encoding arithmetic, logical and/or 1/O operations and includes both a physical and a virtual processor. The processor may, for example, comprise an arithmetic logic unit (ALU), a control unit and a plurality of registers. The processor may comprise a single core processor capable of executing one instruction at a time (or process a single pipeline of instructions) or a multi-core processor which simultaneously executes multiple instructions. The processor may be implemented as a single integrated circuit, two or more integrated circuits, or may be a component of a multi-chip module.

[0018] The various internal components that are included in the generator assembly 14 and renewable generator system 24 may each be sized and rated such that the system is capable of supplying the necessary power required by the pump 12 based on its speed and torque requirements. For example, where the pump 12 is deployed in a borehole for groundwater control, the system 10 may be capable of supplying a total of between 22 and 150 kilowatts (kW) of power to the pump 12.

[0019] The control system 26 may implement a fuel optimization algorithm that controls the extent or ratio at which the first and second alternating currents are supplied to, and/or used to power, the pump 12. The algorithm may perform the algorithm in real time, or near real time, based on the current load conditions and demands of the pump 12 and the current operating characteristics and conditions of the generator assembly 14 and renewable generator system 24. The algorithm may balance the first and second alternating currents such that the necessary power is supplied to the pump 12 in the most efficient way possible that minimises fuel consumption by the engine 16.

[0020] For example, the renewable generator system 24 may comprise a solar generator that is capable of generating and supplying a maximum of 50 kW of electric power. The generator assembly 14 may be capable of generating and supplying a maximum of 100 kW of power. If the pump 12 requires 120 kW of electric power to operate, in optimal weather conditions the control system 26 may cause the renewable generator system 24 to supply 50 kW of power and the generator assembly 14 to supply kW of power. This ensures that the solar generator is used to its maximum advantage and minimises fuel consumption of the engine 16. In sub-optimal weather conditions, the control system 26 may cause the renewable generator system 24 to supply 20 kW of power and the generator assembly 14 to supply 100 kW of power.

[0021] In examples where both the first and second alternating currents are used to power the pump 12 simultaneously (i.e., the two currents are combined together), the control system 26 may cause the generator assembly 14 and the renewable generator system 24 to operate synchronously such that the two alternating currents are in phase with each other. In other examples, the respective alternating currents generated by the generator assembly 14 and renewable generator system 24 may be supplied to the VSD 28 and the VSD 28 may be configured to use the received power to generate the electrical current supplied to the pump 12.

[0022] In other examples, the control system 26 may implement a control mode wherein either only the first alternating current or only the second alternating current is supplied to the pump 12 on a selective basis based on power availability. The control system 26 may execute this control mode for a variety of reasons, including (for example) because the generator assembly 14 has run out of fuel or because the renewable generator system 24 is incapable of producing significant power in the environmental conditions at the relevant time. In other examples, the control system 26 may include a mode wherein the control system 26 causes only the first alternating current or only the second alternating current to be supplied to the pump 12 in response to an instruction issued to the control system 26 by a human operator using an input device.

[0023] A storage device 36 may also be coupled to the control system 26. The storage device 36 may comprise a volatile or non-volatile memory device, such as RAM, ROM, EEPROM or flash memory, a magnetic or optical disk, a network attached storage (NAS) device or any other device capable of storing data. The storage device 36 may be integral with the control system 26 or it may be an external storage device in communication with the control system 26 via a wired or wireless communication means such as, for example, a USB cable, optical fibre, ethernet or WiFi.

[0024] The storage device 36 may store at least one set point relating to an operating environment of the pump 12. Further, in response to receiving signals from one or more environment sensors (not shown) connected to the control system 26, the control system 26 may automatically vary the rotational speed of the pump 12 to maintain the set point. For example, the pump 12 may be deployed in a borehole for controlling ground water. The set point may relate to an operating environment or condition of the pump, such as a constant fluid flow rate, fluid pressure or fluid level of the borehole in which the ESP is operating. In examples where the set point relates to a constant fluid level, if the fluid level in the borehole rises above the set level in use, the control system 26 may automatically increase the speed of the pump 12 so that the pump 12 works harder to bring the fluid level down to the set level (and vice versa if the fluid level falls below the set level). The one or more sensors may comprise a fluid pressure sensor, fluid flow rate sensor, fluid level sensor, temperature sensor, mechanical vibration sensor or any other type of sensor that provides information allowing the relevant set point to be maintained. In examples where a fluid level set point needs to be maintained, such as a level of water in a borehole, the sensor may be a hydrostatic sensor that operates by measuring a fluid pressure indicative of the relevant fluid level. The sensor may also be a guided radar device, an ultrasonic device, a magnetostrictive level transmitter or a conductivity sensor when required to measure a fluid level.

[0025] The control system 26 may also control the rotational speed of the pump 12 in response to feedback received from one or more sensors that measure operating conditions of the pump 12. The sensors may, for example, comprise a temperature sensor that measures an operating temperature of the pump 12 or a vibration sensor that measures mechanical vibrations of the pump 12.

[0026] In one example, the control system 26 may be configured to implement a safety feature wherein the speed of the pump 12 is reduced when a temperature sensor installed in the pump 12 indicates that the temperature of the pump 12 has met or exceeded a particular maximum value set by an operator of the system 10. The temperature sensor may, for example, comprise a positive temperature coefficient resistor, or similar temperature measuring device, communicatively coupled to the control system 26. The control system 26 may also be configured to stop the pump 12 altogether when the maximum temperature value is exceeded.

[0027] The control signals that are issued by the control system 26 to the various components of the system 10 connected to the control system 26 may comprise digital control signals. For example, the system 10 may comprise a communications bus connecting the control system 26 to the components and the control signals may comprise digital machine code instructions transmitted via the communications bus. In other examples, the control system 26 may be connected to the components via an internal packet-switched network and the control signals may comprise data packets transmitted over the network. The internal network may be a controller area network that implements an industry standard message-based protocol such as CANbus or Modbus. In other examples, the control system 26 may be configured to issue analogue control signals, such as reference voltages, to the components.

[0028] The system 10 may also comprise a communications interface 38 for connecting the control system 26 to a control center or device that is remote from the control system 26. For example, the communications interface 38 may comprise a radio transceiver or network interface that enables a remote control device to be connected via a LAN, WAN, WLAN, the Internet, cellular or mobile network or other computer or digital network. The control system 26 may be connectable to an individual remote control device that comprises a touch-screen display, or similar electronic user interface, that enables a human operator to set, activate and monitor the operation of the system 10. In other examples, the control system 26 may be connectable to a remote control centre that contains various UI control devices that human operators may use to control the system 10.

[0029] The control system 26 may also be configured to transmit data relating to operating conditions or parameters of the system 10 to the remote control center or device. This enables the operation and performance of the system 10 to be monitored and assessed during use. The control system 26 may also be configured to operate in accordance with control instructions received from the remote control center or device via the communications interface 38. For example, the user control center or device may be used by an operator to set and store a particular set point on the storage device 36 and cause the control system 26 to operate in accordance with a control mode corresponding to the set point. For example, the operator may store a constant water flow rate in the storage device 36 and cause the control system 26 to enter into a pump control mode wherein the speed of the ESP's electric motor is regulated by the control system 26 to maintain the constant flow rate during use.

[0030] The control system 26 may also be configured to transmit warnings or alerts relating to operating conditions of the system 10 to the remote control center or device via the communications interface 38. For example, the control system 26 may transmit an alert when the temperature of the pump 12 exceeds a particular operating range stored on the storage device 36. The control system 26 may also be configured to transmit warnings or alerts when it predicts when particular operating conditions of the system 10 may occur or arise in the future. The control system 26 may make such predictions based on the historical mode of operation and/or duration of operation of the system 10 that is tracked and recorded by the control system 26.

[0031] A circuit breaker (not shown) may be disposed between the system 10 and the connected pump 12 that prevents the pump 12 from drawing too much current from the system 10 during use. The control system 26 may be communicatively connected to the circuit breaker and configured to monitor and reset the circuit breaker in accordance with programmed logic executed by the control system 26 and/or operator instructions manually issued using the remote control centre or device.

[0032] Referring to Figure 2, an example of the system 10 is depicted wherein the DC generator system 30 comprises a solar generator 40. The solar generator 40 may comprise one or more solar cells connected to the inverter 32. The solar cells 40 may be arranged in flat solar panels that are connected to the outside of a supporting frame or housing (not shown) that the components of the system 10 are contained inside or attached to. In other embodiments, one or more of the solar cells 40 may be integral with the supporting frame or housing. For example, the solar cells 40 may be embedded into elongate supports of the frame. The solar generator may also comprise a regulator 42 that is connected between the solar cells 40 and the inverter 32 for controlling the direct current supplied to the inverter 32.

[0033] The control system 26 may comprise a master controller 44 that is connected to first and second sub-controllers 46, 48. The first sub-controller 46 may be responsible for controlling the components included in the generator assembly 14 and the second sub-controller 48 may be responsible for controlling the components included in the renewable generator system 24. The two sub-controllers 46, 48 may receive instructions from the master controller 44 and, in turn, cause the generator assembly 14 and renewable generator system 24 to operate in accordance with the relevant instructions.

[0034] In other embodiments, the DC renewable generator system 30 may comprise a wind turbine (not shown) or a thermoelectric generator (not shown) connected to the inverter 32. In examples where a thermoelectric generator is used, the thermoelectric generator may convert surplus heat created by the engine 16 or ambient heat of air surrounding the components of the system 10, and/or its supporting frame or housing, into direct current that is supplied to the inverter 32.

[0035] Embodiments of the present invention provide systems and methods that are useful for powering and controlling electric motors, including electric motors of electric submersible pumps.

[0036] For the purpose of this specification, the word "comprising" means "including but not limited to", and the word "comprises" has a corresponding meaning.

[0037] The above embodiments have been described by way of example only and modifications are possible within the scope of the claims that follow.

Claims

1. A system configured to supply electrical power to an electric submersible pump, the system comprising: a portable generator assembly comprising an engine and an alternator mechanically coupled to the engine to generate an alternating current for powering the pump, wherein the alternator comprises an excitation controller operatively configured to control a voltage of the alternating current, and wherein the engine comprises a throttle controller to control a rotational speed of the engine and, therefore, frequency of the alternating current; at least one renewable power generator system for powering the pump; and a control system configured to vary the frequency and the voltage of the alternating current by controlling, respectively, the throttle controller and the excitation controller based on levels of electrical power generated, or capable of being generated, by the renewable power generator system.

2. The system according to claim 1, wherein the control system includes a control mode wherein electric power supplied to the pump is generated by both the portable generator assembly and the renewable power generator system simultaneously.

3. The system according to claim 1 or 2, wherein the control system includes a control mode wherein electric power supplied to the pump is generated by either only the portable generator assembly or only the renewable power generator system selectively.

4. The system according to any one of the preceding claims, wherein the renewable power generator system comprises at least one battery for storing electrical power produced by the renewable power generator system, and wherein the control system includes a control mode wherein electrical power stored in the battery is supplied to the pump.

5. The system according to any one of the preceding claims, wherein the renewable power generator system comprises one or more solar cells connected to an inverter to generate a second alternating current for powering the pump.