Multi-motor variable frequency driving device of high-power electric fracturing pry and control method of multi-motor variable frequency driving device

Abstract

The invention discloses a high-power electric fracturing pry multi-motor variable-frequency driving device and a control method thereof. The high-power electric fracturing pry multi-motor variable-frequency driving device comprises a fracturing pump, a driving system and a control system, the driving system comprises a plurality of motors and a compound box, and the motors jointly drive the fracturing pump through the compound box; the control system comprises an inversion unit, a PLC controller and a PN bus communication network. Each motor is driven by a corresponding inversion unit, a sensor is mounted on each motor, and the plurality of inversion units are connected to form a closed looped network to form a torque closed loop for adjusting parameters of the motors; the PLC comprises a high-speed counting module and an analog quantity input module, and the high-speed counting module collects rotating speed signals of the motor in real time through a rotating speed sensor installed on the motor; the PLC controller is connected with the inversion unit through a PN bus communication network. According to the invention, the problem of low energy efficiency ratio caused by the fact that a plurality of motors need to be put into driving the fracturing pump under any working condition in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of electric drive for a fracturing skid, and more specifically, to a high-power electric fracturing skid multi-motor variable frequency drive device and a control method thereof. Background Art

[0002] After decades of development, major oil fields have seen their underground reservoirs become dominated by heavy oil. Heavy oil has poor fluidity, leading to reduced oil production. Oil fields are seeking high-pressure, high-volume injection devices to inject liquid into the formation and remove the heavy oil, thereby increasing production. In recent years, with the development of power grids across oil fields, electric power grids have become ubiquitous across oil regions. Due to their noise-free, oil-free, and environmentally friendly characteristics, electric fracturing technology, while addressing the source of the problem, has gradually gained attention due to its high efficiency, low noise, and ease of control. However, existing electric fracturing technology often relies on high-power motors, which have low energy efficiency under low-pressure, low-volume conditions. Furthermore, if the motor fails, the corresponding hydraulic horsepower is lost, compromising the efficiency and safety of the entire fracturing operation. Summary of the Invention

[0003] In response to the multi-motor distributed electric drive device of the existing fracturing system, the present invention provides a high-power electric fracturing skid multi-motor variable frequency drive device and its control method, which solves the problem of low energy efficiency caused by the need to use all multiple motors to drive the fracturing pump under any working conditions in the existing technology.

[0004] The technical solution adopted by the present invention to solve this technical problem is: a high-power electric fracturing skid multi-motor variable frequency drive device, including: a fracturing pump, a drive system and a control system; The driving system includes a plurality of motors and a parallel box, wherein the plurality of motors drive the fracturing pump together through the parallel box; The control system includes an inverter unit, a PLC controller, and a PN bus communication network; each motor is driven by a corresponding inverter unit, and sensors are installed on the motors. Several inverter units are connected to form a closed loop network, forming a torque closed loop for adjusting the parameters of the motors; The PLC controller includes a high-speed counting module and an analog input module. The high-speed counting module collects the motor's speed signal in real time through a speed sensor installed on the motor. The PLC controller is connected to the inverter unit via a PN bus communication network, and collects the motor's parameter data through the PN bus communication network. The PLC controller processes the collected data and transmits the control parameters to the inverter unit via the PN bus communication network based on the processing results, thereby adjusting the motor's operating parameters in real time.

[0005] As a further solution of the present invention, the sensors include a rotation speed sensor, a voltage sensor, a current sensor, a torque sensor and a temperature sensor.

[0006] The present invention also provides a control method using the device, comprising: Speed loop control: When the equipment is running, the high-speed counting module of the PLC system collects the motor speed in real time through the speed sensor installed on the motor. At the same time, it collects the motor data through the PN bus communication network and processes the collected data synchronously. According to the processing results, the output frequency of each motor is adjusted in real time to form a complete speed loop to ensure that all motors run at the same frequency. Torque closed-loop control: Each inverter unit is connected to a motor to drive the motor. Each motor shaft concentrates power through multiple input shafts of the parallel box to drive the fracturing pump. Each inverter unit is connected end to end through the PN bus communication network to form a network closed loop. Through the PN bus network, the inverter units coordinate to adjust the output torque to form a torque closed loop.

[0007] As a further solution of the present invention, in the speed loop control, one of the online motors is used as a virtual master motor, with its speed as the target, and the other motors follow the speed. If this motor exits due to a fault, another one is randomly used as the virtual master motor, and so on, thereby achieving speed synchronization of multiple motors.

[0008] As a further solution of the present invention, in the torque closed-loop control, the control system calculates the total load of the inverter units, and obtains the average load of each motor based on the total load. This average is used as the anchor value of the motor torque output, and the inverter units coordinate with each other to ensure balanced output load of each motor; Moreover, the motor load calculation and distribution process does not require uploading data to the PLC controller for processing. Instead, the inverter unit edge computing method is used to quickly obtain results and adjust control parameters in real time.

[0009] As a further solution of the present invention, according to the specific requirements of the fracturing operation process, the inverter unit collects the voltage and current data of the motor, calculates the motor power and torque values based on the voltage and current data, and thus calculates and controls the number of motors driven in the current operation and the initial operating parameters of each motor.

[0010] A further solution of the present invention is: a fault diagnosis and processing method comprising the following steps: B1. Once a running motor is diagnosed as faulty; B2. The PLC controller issues a command, causing the inverter unit to shut down the faulty motor and simultaneously bring the idle motor online to ensure continuous fracturing operations.

[0011] The present invention has at least the following beneficial effects: 1. Accurately control the pressure and flow of fracturing equipment by precisely controlling the coordinated work of multiple motors.

[0012] 2. The number of motors driven by the current operation and the initial operating parameters of each motor are automatically set according to the operation requirements, so that each motor is in a high-efficiency constant power range with a high energy efficiency ratio.

[0013] 3. A control strategy is adopted to automatically eject faulty motors and actively engage backup motors. If a motor fails, the faulty motor will automatically exit the drive chain, and the backup motor will quickly switch in to compensate for the lost power, keeping the equipment in optimal working condition without stopping the pump, minimizing the impact on the fracturing operation.

[0014] 4. A dual closed-loop control strategy is adopted for the motor’s speed loop and the torque loop between the frequency conversion units to adjust the speed and torque of multiple motors for synchronous operation, thereby efficiently realizing the coordinated synchronous control function of multiple motors.

[0015] Other advantages, objectives and features of the present invention will be reflected in part from the following description and will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of a multi-motor variable frequency driven fracturing pump.

[0017] Figure 2 This is a schematic diagram of a multi-motor variable frequency drive control strategy for an electric fracturing skid.

[0018] Figure 3 This is a schematic diagram of fault diagnosis and treatment for a multi-motor variable frequency drive of an electric fracturing skid.

[0019] Among them, 1-motor, 2-carriage box support frame, 3-carriage box, 4-fracturing pump. DETAILED DESCRIPTION

[0020] The present invention is described in detail and completely below with reference to the accompanying drawings. Those skilled in the art will be able to implement the present invention based on this description. Before describing the present invention with reference to the accompanying drawings, it should be noted that the technical solutions and technical features provided in various parts of the present invention, including those described below, may be combined with each other unless they conflict.

[0021] In addition, the embodiments of the present invention described below are generally only part of the embodiments of the present invention, rather than all of the embodiments. Therefore, based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making any creative efforts should fall within the scope of protection of the present invention.

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The specific implementation process is as follows: like Figures 1-3 As shown, the present invention provides a high-power electric fracturing skid multi-motor variable frequency drive device, comprising: a fracturing pump 4, a drive system and a control system; The drive system includes several motors 1 and a paralleling box 3. In this embodiment, the motors 1 are automotive-grade motors that comply with automotive industry standards (such as ISO 16750 and AEC-Q200). The term "motor" generally refers to compact motors with power ranging from tens to hundreds of kilowatts, for example: diameter: 100mm-500mm; power: 10kW-200kW; type: stepper motor, AC variable frequency motor, permanent magnet synchronous motor, etc. The motors 1 collectively drive the fracturing pump 4 through the paralleling box, which is fixed by the paralleling box support frame 2. The control system includes an inverter unit, a PLC controller, and a PN bus communication network; each motor is driven by a corresponding inverter unit, and sensors are installed on the motors. Several inverter units are connected to form a closed loop network, forming a torque closed loop for adjusting the parameters of the motors; The PLC controller includes a high-speed counting module, an analog input module, etc. The high-speed counting module collects the motor's speed signal in real time through a speed sensor installed on the motor; the PLC controller is connected to the inverter unit via a PN bus communication network, and collects the motor's parameter data (current, voltage, etc.) through the PN bus communication network. The PLC controller processes the collected data and transmits the control parameters to the inverter unit through the PN bus communication network based on the processing results. The motor's operating parameters are adjusted in real time to form a complete speed loop, ensuring that the motors run at the same frequency to meet operational requirements.

[0023] This technical solution may also include the following technical details to better achieve the technical effect: the sensors include a speed sensor, a voltage sensor, a current sensor, a torque sensor and a temperature sensor, wherein the temperature sensor (PT100) is pre-embedded in the motor coil and bearing.

[0024] The present invention also provides a control method using the device, comprising: Speed loop control: When the equipment is running, the high-speed counting module of the PLC system collects the motor speed in real time through the speed sensor installed on the motor. At the same time, it collects the motor data through the PN bus communication network and processes the collected data synchronously. According to the processing results, the output frequency of each motor is adjusted in real time to form a complete speed loop to ensure that all motors run at the same frequency. Torque closed loop control: Figure 2 As shown, in the multi-motor synchronous control system, each inverter unit is connected to an automotive-grade motor to drive the motor. Each motor shaft concentrates power through multiple input shafts of the parallel box to drive the fracturing pump 4. Each inverter unit is connected end to end through the PN bus communication network to form a network closed loop. Through the PN bus network, the inverter units coordinate to adjust the output torque to form a torque closed loop.

[0025] Through this dual closed-loop control logic and algorithm, motor operating parameters are optimized in real time to adapt to changes during operation. Based on these optimized parameters, a multi-motor coordinated control strategy is implemented to ensure coordinated operation of each motor, enabling precise control of pressure and flow within the fracturing equipment.

[0026] This technical solution can also include the following technical details to better achieve the technical effect: In the speed loop control, the multi-motor synchronous control system collects the speed signals of multiple automotive-grade motors through PLC, and then transmits the control signal to the inverter unit through the PN bus to adjust the output speed of each slave shaft motor, that is, one of the online motors is used as a virtual master motor, and its speed is used as the target, and the remaining motors follow the speed. If this motor exits due to a fault, another one is randomly used as the virtual master motor, and so on, thereby achieving speed synchronization of multiple motors.

[0027] This technical solution may also include the following technical details to better achieve the technical effect: In the torque closed-loop control, the control system calculates the total load of the inverter unit, and obtains the average load of each motor based on the total load. This average is used as the anchor value of the motor torque output. The inverter units coordinate with each other to ensure balanced output load of each motor; Furthermore, the motor load calculation and distribution process does not require data to be uploaded to the PLC controller for processing. Instead, edge computing in the inverter unit is used to rapidly generate results and adjust control parameters in real time, significantly improving the efficiency of multi-motor load balancing. Based on the actual operating conditions of the fracturing equipment, motor operating parameters (speed, torque) are adjusted through real-time feedback, ensuring that the performance of the participating motors remains within the high-efficiency operating range (each motor operates in a constant power range), ensuring optimal energy efficiency for the entire operation.

[0028] This technical solution may also include the following technical details to better achieve the technical effect: according to the specific requirements of the fracturing operation process, the inverter unit collects the voltage and current data of the motor, calculates the motor power and torque values based on the voltage and current data, and thus calculates and controls the number of motors driven in the current operation and the initial operating parameters of each motor, including speed, torque, and power.

[0029] This technical solution may also include the following technical details to better achieve the technical effect: a fault diagnosis and processing method, including the following steps: B1. Figure 3 As shown in the figure, once a running motor (M3) is diagnosed as faulty, there are many reasons for the motor failure, including the following situations: 1. The inverter unit fails due to breakdown of the power element, and cannot output the control current to drive the motor to run. At this time, the inverter unit will automatically report the fault information to the PLC system; 2. The motor itself fails, such as the winding temperature is too high, the bearing temperature is too high, etc.; 3. The motor has overvoltage or overcurrent faults; 4. The motor has short circuit faults. Except for the second item which is directly collected by the PLC, the rest are reported to the PLC system through the inverter unit.

[0030] B2. The PLC controller issues a command, causing the inverter unit to deactivate the faulty motor and simultaneously bring the idle motor (Mn) online to ensure continuous fracturing operations. Specifically, the inverter unit enable signal corresponding to the faulty motor is reset to 0, depriving the corresponding motor coil of excitation current and halting operation. In the above-described embodiment, fault diagnosis and measures are implemented by real-time monitoring of the motor's operating status. If a motor failure is detected, the faulty motor is automatically deactivated from the drive train, and the backup motor quickly switches in to compensate for the lost power, ensuring optimal operation of the equipment at all times.

[0031] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A high-power electric fracturing skid multi-motor variable frequency drive device, characterized in that: include: fracturing pumps, drive systems, and control systems; The driving system includes a plurality of motors and a parallel box, wherein the plurality of motors drive the fracturing pump together through the parallel box; The control system includes an inverter unit, a PLC controller and a PN bus communication network; each motor is driven by a corresponding inverter unit, a sensor is installed on the motor, and several inverter units are connected to form a closed loop network, forming a torque closed loop for adjusting the parameters of the motor; the PLC controller includes a high-speed counting module and an analog input module, and the high-speed counting module collects the motor speed signal in real time through the speed sensor installed on the motor; the PLC controller is connected to the inverter unit via the PN bus communication network, collects the motor parameter data through the PN bus communication network, processes the collected data, and transmits the control parameters to the inverter unit through the PN bus communication network according to the processing results, so as to adjust the motor operating parameters in real time.

2. The high-power electric fracturing skid multi-motor variable frequency drive device according to claim 1, characterized in that: The sensors include a rotation speed sensor, a voltage sensor, a current sensor, a torque sensor and a temperature sensor.

3. A control method using the device according to claim 2, characterized in that: include: Speed loop control: When the equipment is running, the high-speed counting module of the PLC system collects the motor speed in real time through the speed sensor installed on the motor. At the same time, it collects the motor data through the PN bus communication network and processes the collected data synchronously. According to the processing results, the output frequency of each motor is adjusted in real time to form a complete speed loop to ensure that all motors run at the same frequency. Torque closed-loop control: Each inverter unit is connected to a motor to drive the motor. Each motor shaft concentrates power through multiple input shafts of the parallel box to drive the fracturing pump. Each inverter unit is connected end to end through the PN bus communication network to form a network closed loop. Through the PN bus network, the inverter units coordinate to adjust the output torque to form a torque closed loop.

4. The control method of the device according to claim 3, characterized in that: In the speed loop control, one of the online motors is used as a virtual master motor, with its speed as the target, and the other motors follow the speed. If this motor exits due to a fault, another one is randomly used as the virtual master motor, and so on, thereby achieving speed synchronization of multiple motors.

5. The control method of the device according to claim 3, characterized in that: In the torque closed-loop control, the control system calculates the total load of the inverter unit, and obtains the average load of each motor based on the total load. This average is used as the anchor value for the motor torque output. The inverter units coordinate with each other to ensure balanced output load of each motor. Moreover, the motor load calculation and distribution process does not require uploading data to the PLC controller for processing. Instead, the inverter unit edge computing method is used to quickly obtain results and adjust control parameters in real time.

6. The control method of the device according to claim 3, characterized in that: According to the specific requirements of the fracturing operation process, the inverter unit collects the voltage and current data of the motor, calculates the motor power and torque values based on the voltage and current data, and thus calculates and controls the number of motors driven in the current operation and the initial operating parameters of each motor.

7. The control method of the device according to claim 3, characterized in that: The fault diagnosis and treatment method includes the following steps: B1. Once a running motor is diagnosed as faulty; B2. The PLC controller issues a command, causing the inverter unit to shut down the faulty motor and simultaneously bring the idle motor online to ensure continuous fracturing operations.

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