AU2022287680A1

AU2022287680A1 - Hybrid generator

Info

Publication number: AU2022287680A1
Application number: AU2022287680A
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: 2022-12-17
Publication date: 2023-02-02
Also published as: AU2022100063A4; AU2022100192A4; AU2021107635B4; AU2021201656A1; AU2021107641A4; AU2021107635A4; AU2021107650B4; AU2021107650A4

Abstract

A system configured to power and control an electric pump comprises a mobile generator comprising an engine and an alternator for supplying a first alternating current to the pump. The alternator comprises an excitation controller to control a voltage of the first alternating current. The engine comprises a throttle controller for controlling the engine's speed and, therefore, frequency of the first alternating current. A renewable power system supplies a second alternating current to the pump. A sensor measures a state or condition of fluid pumped using the pump. A control system receive signals from the sensor corresponding to the state or condition and varies a pump operating speed in response to the signals by (i) varying the frequency and the voltage of the first alternating current by controlling, respectively, the throttle controller and excitation controller, and (ii) varying the frequency and the voltage of the second alternating current by controlling the renewable power system.

Description

HYBRID GENERATOR Field

[0001] The present invention relates to electricity generation and, more particularly, a mobile hybrid generator system for powering and controlling electric pumps.

Background

[0002] Electric pumps 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 the 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 not environmentally friendly. Renewable energy generators, such as solar generators, may be used to power an electric pump 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 electric pump, then the renewable 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 electric pumps to be powered and controlled in a fuel efficient manner.

[0005] In this context, there is a need for improved systems for powering and controlling electric pumps.

Summary

[0006] According to the present invention, there is provided a system configured to power and control an electric pump, wherein the system comprises: a mobile generator assembly comprising an engine and an alternator mechanically coupled to the engine for supplying a first alternating current to the electric pump, wherein the alternator comprises a voltage regulator comprising an excitation controller operatively configured to control a voltage of the first alternating current, and wherein the engine comprises a throttle controller for controlling a rotational speed of the engine and, therefore, frequency of the first alternating current; at least one renewable power system for supplying a second alternating current to the electric pump; at least one sensor for measuring a state or condition of the electric pump or of fluid pumped by the electric pump; and a control system connected to the mobile generator assembly and renewable power system, wherein the control system is configured to receive signals output by the sensor, the signals corresponding to the state or condition measured by the sensor, and to operatively vary an operating speed of the electric pump in response to the signals by: varying the frequency and the voltage of the first alternating current supplied to the electric pump by controlling, respectively, the throttle controller and the excitation controller; and varying the frequency and the voltage of the second alternating current supplied to the electric pump by controlling the renewable power system.

[0007] The control system may be configured to optimise relative amounts of the first alternating current and second alternating current that are supplied to the electric pump based on load conditions of the electric pump and operating characteristics of the generator assembly and renewable power system to minimise fuel consumption of the engine.

[0008] The control system may cause the generator assembly and renewable power system to operate synchronously such that the first and second alternating currents are in phase with each other.

[0009] The control system may implement a control mode wherein either only the first alternating current or only the second alternating current is supplied to the electric pump. In such examples, the control system may automatically control whether only the first alternating current or only the second alternating current is supplied to the electric pump based on power that is available from the renewable power system.

[0010] The renewable power system may comprise a variable speed drive for controlling the frequency and voltage of the second alternating current supplied to the electric pump.

[0011] The renewable power system may comprise a renewable DC generator connected to a first inverter, wherein the first inverter converts direct current generated by the renewable DC generator into the second alternating current.

[0012] The renewable power system may comprise at least one battery that is charged by the renewable DC generator. In such examples, the control system may cause electricity stored in the battery to be supplied to the first inverter.

[0013] The renewable DC generator may comprise a solar generator comprising one or more solar cells connected to the first inverter.

[0014] The solar generator may comprise a regulator connected between the solar cells and the first inverter for controlling the direct current supplied to the first inverter.

[0015] The system may comprise a storage device coupled to the control system that stores at least one set point relating to the state or condition measured by the sensor. In response to the signals received from the sensor, the control system may automatically vary the rotational speed of the electric pump so as to maintain the set point.

[0016] The system may comprise a communications interface for connecting the control system to a control center or device that is remote from the control system. The control system may send and receive data to and from the control center or device relating to operation of the system via the communications interface.

[0017] The control system may operate in accordance with control instructions received from the control center or device via the communications interface.

[0018] The control system may transmit data relating to operating conditions or parameters of the system to the control center or device via the communications interface.

[0019] The control system may transmit warnings or alerts to the control center or device via the communications interface, wherein the warnings or alerts relate to operating conditions of the system. The control system may transmit the warnings or alerts when the control system predicts when the operating conditions of the system may occur or arise. The control system may be configured to predict when the operating conditions of the system may occur or arise based on a mode of operation and/or duration of operation of the system tracked by the control system.

Brief Description of Drawings

[0020] 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 power and control an electric pump according to an example embodiment of the invention; and Figure 2 is a schematic diagram of a system configured to power and control an electric pump according to a further example embodiment of the invention.

Description of Embodiments

[0021] Referring to Figure 1, an example embodiment of the present invention provides a system 10 configured to power and control an electric pump 12. The system 10 comprises a mobile generator assembly 14 that comprises an engine 16 and an alternator 18 mechanically coupled to the engine 16 for supplying a first alternating current to the electric pump 12. The alternator 18 comprises a voltage regulator comprising an excitation controller 20 operatively configured to control a voltage of the first alternating current. The engine 16 comprises a throttle controller 22 for controlling a rotational speed of the engine 16 and, therefore, frequency of the first alternating current. The system 10 also comprises at least one renewable power system 24 for supplying a second alternating current to the electric pump 12. The system 10 also comprises at least one sensor 25 for measuring a state or condition of the electric pump 12 or fluid pumped using the electric pump 12.

[0022] A control system 26 is connected to the generator assembly 14, renewable power system 24 and sensor 25. The control system 26 receives signals output by the sensor 25, wherein the signals correspond to the relevant state or condition measured by the sensor 25. The control system 26 is configured to operatively vary an operating speed of the electric pump 12 in response to the signals by (i) varying the frequency and the voltage of the first alternating current that is supplied to the electric pump 12 by controlling, respectively, the throttle controller 22 and the excitation controller 20; and (ii) varying the frequency and the voltage of the second alternating current that is supplied to the electric pump 12 by controlling the renewable power system 24.

[0023] More particularly, the renewable power system 24 generates electric power independently of the generator assembly 14 using one or more renewable energy sources. This electric power is supplied to the electric pump 12 in the form of the second alternating current. The renewable power system 24 may comprise a variable speed drive (VSD) 28 to control the frequency and voltage of the second alternating current supplied to the electric pump 12. 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 second alternating current generated by the renewable power system 24 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 electric 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.

[0024] 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 that is generated by the alternator 18. The AC voltage regulator 20 comprises an excitation controller or system that is 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 the voltage regulator 20, together, to control the final frequency and voltage of the first alternating current that is received by the electric pump 12 to, therefore, control the operating speed of the electric pump 12.

[0025] The renewable power system 24 may comprise a variety of different devices and components for producing electric power independently of the generator assembly 14. In the example depicted, the renewable power system 24 comprises a renewable direct current (DC) generator 30 that is connected to an inverter 32. Preferably, the renewable DC generator 30 comprises a solar generator or wind turbine.

[0026] The inverter 32 converts DC electricity produced by the DC generator 30 into AC electricity that is supplied to the VSD 28. The renewable power system 24 may also comprise at least one battery 34 that is charged by the 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 not, by its own, capable of supplying the necessary electric power to operate the electric pump 12 at a required speed.

[0027] 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.

[0028] The various internal components that are included in the generator assembly 14 and renewable power system 24 may each be sized and rated such that the system 10 is capable of supplying the necessary power required by the electric pump 12 based on its speed and torque requirements. For example, where the electric pump 12 is used to drive an ESP 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 electric pump 12.

[0029] 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 the electric pump 12 by, respectively, the generator assembly 14 and renewable power system 24. The algorithm may perform this algorithm in real time, or near real time, based on (i) the current load conditions and demands of the electric pump 12 and (ii) the current operating characteristics and conditions of the generator assembly 14 and renewable power system 24 and associated levels of available power. The algorithm may balance the first and second alternating currents such that the necessary power is supplied to the electric pump 12 in the most efficient way possible that minimises fuel consumption of the engine 16.

[0030] For example, the renewable power 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 electric pump 12 requires 120 kW of electric power to operate, in optimal weather conditions the control system 26 may cause the renewable power system 24 to supply 50 kW of power and the generator assembly 14 to supply 70 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 power system 24 to supply 20 kW of power and the generator assembly 14 to supply 100 kW of power.

[0031] In examples where both the first and second alternating currents are supplied to the electric pump 12 (i.e., the two currents are combined together), the control system 26 may cause the generator assembly 14 and the renewable power system 24 to operate synchronously such that the two alternating currents are in phase with each other.

[0032] 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 electric pump 12 on a selective basis. The control system 26 may execute this control mode for a variety of reasons, including because the generator assembly 14 has run out of fuel or because the renewable power system 24 is incapable of generating required power due to poor weather conditions. The control system 26 may control whether only the first alternating current or only the second alternating current is supplied to the electric pump 12 automatically based on the level of power that is available from the renewable power system 24. In other examples, the control system 26 may control whether only the first alternating current or only the second alternating current is supplied to the electric pump 12 in response to an instruction issued to the control system 26 by a human operator using an input device.

[0033] 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.

[0034] The storage device 36 may store at least one set point. The set point may relate to an operating condition of the electric pump 12 or to an operating environment of the electric pump 12. In examples where the set point relates to an operating environment, the set point may relate to a process performed in the environment using the pump, such as fluid that is pumped using the pump. In response to receiving signals from sensor 25, the control system 26 may automatically vary the rotational speed of the electric pump 12 to maintain the set point. For example, the electric pump 12 may drive an ESP that is deployed in a borehole for controlling groundwater. The set point may relate to a flow rate, pressure or borehole level of water that is pumped by the ESP. 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's motor 12 so that the ESP 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 sensor 25 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.

[0035] In one example, the control system 26 may be configured to implement a safety feature wherein the speed of the electric pump 12 is reduced when a temperature sensor installed in the pump 12 indicates that the temperature of the pump's motor 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 electric pump 12 altogether when the maximum temperature value is exceeded.

[0036] 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.

[0037] 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.

[0038] 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, if the pump 12 is an ESP, the operator may store a water flow rate set point in the storage device 36 and cause the control system

26 to enter into a pump control mode wherein the speed of the ESP is regulated by the control system 26 to maintain the constant flow rate during use.

[0039] 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 electric 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.

[0040] A circuit breaker (not shown) may be disposed between the system 10 and the connected electric pump 12 that prevents the electric 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.

[0041] Referring to Figure 2, an example of the system 10 is depicted wherein the DC generator system 30 comprises a solar generator. The solar generator may comprise one or more solar cells 40 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.

[0042] 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 power 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 power system 24 to operate in accordance with the relevant instructions.

[0043] In other embodiments, the DC 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.

[0044] Embodiments of the present invention provide systems and methods that are useful for powering and controlling electric pumps, including electric pumps of electric submersible pumps.

[0045] For the purpose of this specification, the word "comprising" means "including but not limited to", and the word "comprises" has a corresponding meaning.

[0046] 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 power and control an electric pump, the system comprising: a mobile generator assembly comprising an engine and an alternator mechanically coupled to the engine for supplying a first alternating current to the electric pump, wherein the alternator comprises a voltage regulator comprising an excitation controller operatively configured to control a voltage of the first alternating current, and wherein the engine comprises a throttle controller for controlling a rotational speed of the engine and, therefore, frequency of the first alternating current; at least one renewable power system for supplying a second alternating current to the electric pump; at least one sensor for measuring a state or condition of the electric pump or of fluid pumped by the electric pump; and a control system connected to the mobile generator assembly and renewable power system, wherein the control system is configured to receive signals output by the sensor, the signals corresponding to the state or condition measured by the sensor, and to operatively vary an operating speed of the electric pump in response to the signals by: varying the frequency and the voltage of the first alternating current supplied to the electric pump by controlling, respectively, the throttle controller and the excitation controller; and varying the frequency and the voltage of the second alternating current supplied to the electric pump by controlling the renewable power system.

2. The system according to claim 1, wherein the control system is configured to optimise relative amounts of the first alternating current and second alternating current that are supplied to the electric pump based on load conditions of the electric pump and operating characteristics of the generator assembly and renewable power system to minimise fuel consumption of the engine.

3. The system according to claim 1 or 2, wherein the control system causes the generator assembly and renewable power system to operate synchronously such that the first and second alternating currents are in phase with each other.

4. The system according to claim 1, wherein the control system implements a control mode wherein either only the first alternating current or only the second alternating current is supplied to the electric pump.

5. The system according to claim 4, wherein the control system automatically controls whether only the first alternating current or only the second alternating current is supplied to the electric pump based on power that is available from the renewable power system.

6. The system according to any one of the preceding claims, wherein the renewable power system comprises a variable speed drive for controlling the frequency and voltage of the second alternating current supplied to the electric pump.

7. The system according to any one of the preceding claims, wherein the renewable power system comprises a renewable DC generator connected to a first inverter, wherein the first inverter converts direct current generated by the renewable DC generator into the second alternating current.

8. The system according to claim 7, wherein the renewable power system comprises at least one battery charged by the renewable DC generator, and wherein the control system is configured to cause electricity stored in the battery to be supplied to the first inverter.

9. The system according to claim 7 or 8, wherein the renewable DC generator comprises a solar generator comprising one or more solar cells connected to the first inverter.

10. The system according to claim 9, wherein the solar generator comprises a regulator connected between the solar cells and the first inverter for controlling the direct current supplied to the first inverter.

11. The system according to any one of the preceding claims, wherein: the system comprises a storage device coupled to the control system that stores at least one set point relating to the state or condition measured by the sensor; and in response to the signals received from the sensor, the control system automatically varies the rotational speed of the electric pump to maintain the set point.

12. The system according to claim 11, wherein the set point is a flow rate of fluid pumped by the electric pump.

13. The system according to any one of the preceding claims, wherein the system comprises a communications interface for connecting the control system to a control center or device that is remote from the control system, and wherein the control system is configured to send and receive data to and from the control center or device relating to operation of the system via the communications interface.

14. The system according to claim 13, wherein the control system is configured to operate in accordance with control instructions received from the control center or device via the communications interface.

15. The system according to claim 13 or 14, wherein the control system is configured to transmit data relating to operating conditions or parameters of the system to the control center or device via the communications interface.