Pump-controlled energy-saving pumping unit system based on direct-current bus capacitor energy storage and control method

Abstract

This invention provides a pump-controlled energy-saving oil pumping unit system and control method based on DC bus capacitor energy storage, relating to the field of oil pumping units. The system includes a power module, an oil replenishment module, a safety overflow module, a balance compensation module, a safety unloading module, a parameter detection module, an actuator module, and a drive control module, recovering and utilizing the gravitational potential energy of the load. The control method of this invention includes detecting the voltage at the supercapacitor terminals and the working terminal voltage, calculating the current state of charge (SOC), determining whether it is at its maximum value, and determining the operating condition of the servo motor, charging and discharging the supercapacitor to store energy or provide energy to the system. This invention eliminates throttling and overflow losses. Targeting the gravitational potential energy generated during the operation of the oil pumping unit, a servo motor drives the pump motor as a power source to recover and utilize the generated gravitational potential energy, improving the system's energy utilization efficiency. Furthermore, multiple operating conditions such as emergency stop, unloading, and pressure holding can be achieved using only a single two-position four-way solenoid directional valve.

Description

Technical Field

[0001] This invention belongs to the field of oil pumping unit technology, specifically relating to a pump-controlled energy-saving oil pumping unit system and control method based on DC bus capacitor energy storage. Background Technology

[0002] As a strategic energy reserve, oil has a profound impact on a country's economy, security, and development. Oil pumping units play a crucial role in the oil extraction process. Most existing oil pumping units use traditional valve control systems, which suffer from significant throttling and overflow losses, resulting in low efficiency and high energy consumption during oil extraction. Furthermore, traditional valve control systems require auxiliary equipment such as oil tanks and cooling towers, necessitating a large land area and significantly impacting the actual extraction process.

[0003] Therefore, a new pump-controlled hydraulic system and energy recovery control method for oil pumping units are needed to address the aforementioned shortcomings. Summary of the Invention

[0004] To address the shortcomings of the existing technology, the present invention aims to provide a pump-controlled energy-saving oil pumping unit system and control method based on DC bus capacitor energy storage. Compared with traditional valve control systems, it eliminates throttling and overflow losses, eliminates the need for oil tanks and cooling towers as auxiliary equipment, and offers high efficiency and a small footprint. The present invention utilizes a servo motor to drive the pump motor as a power source to recover and reuse the gravitational potential energy generated during the operation of the oil pumping unit, thereby reducing system energy consumption and improving system energy utilization efficiency.

[0005] Specifically, on one hand, the present invention provides a pump-controlled energy-saving oil pumping unit system based on DC bus capacitor energy storage, which includes a power module, an oil replenishment module, a safety overflow module, a balance compensation module, a safety unloading module, a parameter detection module, an actuator module, and a drive control module. The power module includes a servo motor, a coupling, and a bidirectional pump motor; the oil replenishment module includes a first check valve, a second check valve, an energy accumulator, and a third pressure relay; the safety overflow module includes a first overflow valve and a second overflow valve; the balance compensation module includes a first hydraulically controlled check valve and a second hydraulically controlled check valve; the safety unloading module is configured as a two-position four-way solenoid directional valve; the parameter detection module includes a flow meter, a first pressure relay, and a second pressure relay; the actuator module includes a hydraulic cylinder, a speed sensor, a displacement sensor, and a force sensor; and the drive control module includes a motion controller, a driver, and a supercapacitor.

[0006] The first check valve is connected to the second check valve, and both are connected to the bidirectional pump motor. The first relief valve is connected to the second relief valve, and both are connected to the bidirectional pump motor. The first hydraulically controlled check valve is connected to the second hydraulically controlled check valve and the first relief valve. The second hydraulically controlled check valve is connected to the second relief valve. The two-position four-way solenoid directional valve is connected to the first hydraulically controlled check valve, the second hydraulically controlled check valve, the flow meter, the hydraulic cylinder, and the second pressure relay. The flow meter is connected to the first pressure relay and the hydraulic cylinder.

[0007] The motion controller connects to the driver, servo motor, flow meter, first pressure relay, second pressure relay, speed sensor, displacement sensor, and force sensor. The driver connects to the servo motor and power supply. The driver and supercapacitor are connected via a DC bus.

[0008] Preferably, the bidirectional pump motor is provided with a first oil port, a second oil port and a third oil port. The first oil port is connected to a first check valve, the second oil port is connected to a second check valve, and the third oil port is connected to a low-pressure channel. The servo motor and the bidirectional pump motor are connected by a coupling.

[0009] Preferably, the speed sensor, displacement sensor, and force sensor are mounted on the hydraulic cylinder and connected to the motion controller via wires.

[0010] Preferably, the control oil circuit of the first hydraulic check valve is connected to the low-pressure channel, and the control oil circuit of the second hydraulic check valve is connected to the high-pressure channel.

[0011] Preferably, the accumulator is connected to a second one-way valve and a two-way pump motor, the accumulator is connected to an oil drain channel, and a third pressure relay is installed at the oil port of the accumulator.

[0012] On the other hand, the present invention provides an energy recovery control method for a pump-controlled energy-saving oil pumping unit system based on DC bus capacitor energy storage, which includes the following steps:

[0013] S1: Detects the maximum, minimum, and operating terminal voltages of the supercapacitor.

[0014] S2: Determine the servo motor operating condition. If it is the generator operating condition, calculate the current supercapacitor state of charge (SOC) and execute step S3. If it is the motor operating condition or standby operating condition, execute step S4.

[0015] S3: Determine if the state of charge (SOC) is at its maximum value. If yes, stop charging the supercapacitor. If no, charge the supercapacitor until the SOC reaches its maximum value, and then proceed to step S4.

[0016] S4: Determine if the servo motor is in motor operation mode. If yes, proceed to step S5. If it is in standby mode, end the process.

[0017] S5: Determine if the state of charge (SOC) is at its maximum value. If yes, proceed to step S6; otherwise, proceed to step S2.

[0018] S6: The supercapacitor discharges and works with the power supply to power the servo motor.

[0019] S7: Determine if the state of charge (SOC) of the supercapacitor is at its minimum value. If yes, the supercapacitor stops discharging and waits to be charged, then proceed to step S1. If no, return to step S6.

[0020] Preferably, in step S2, the formula for calculating the state of charge (SOC) of the supercapacitor is as follows:

[0021]

[0022] In the formula, U SCmax U is the maximum terminal voltage of the supercapacitor. SCmin U is the minimum terminal voltage of the supercapacitor. SC This is the operating voltage of the supercapacitor.

[0023] Furthermore, preferably, to avoid overcharging and over-discharging of the supercapacitor, the maximum and minimum values ​​of the supercapacitor's state of charge (SOC) are 0.9 and 0.45, respectively.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] (1) The present invention uses a pump-controlled closed hydraulic system, which has no throttling overflow loss, a large power-to-weight ratio and high efficiency compared with the traditional valve-controlled hydraulic system. Compared with the traditional valve-controlled hydraulic system, the oil tank volume is greatly reduced, the floor space is small, the space utilization rate is high, and it is more convenient to use.

[0026] (2) The hydraulic system of the present invention has been innovated in principle. It can realize multiple working conditions such as emergency stop, unloading and pressure holding by using only a two-position four-way solenoid directional valve. Compared with the traditional system, it reduces the number of failure points, is easy to operate, and can significantly reduce costs.

[0027] (3) This invention employs a servo motor coaxially driven variable pump. The hydraulic pump has four-quadrant operation capability. During pump operation, the output flow rate controls the position, speed, and output of the hydraulic cylinder, consuming energy at this time. When the pumping unit experiences overload conditions, the pump operation switches to motor operation, and the servo motor functions as a generator, increasing the bus voltage and storing electrical energy in the supercapacitor, thus feeding back energy. In the next energy-consuming operation, the electrical energy stored in the supercapacitor is utilized, improving energy utilization efficiency. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the closed-loop pump-controlled hydraulic system of the oil pumping unit of the present invention;

[0029] Figure 2 This is a schematic diagram of the functional blocks of the closed-loop pump-controlled hydraulic system of the oil pumping unit of the present invention;

[0030] Figure 3 This is a flowchart illustrating the control strategy of the closed-loop pump-controlled hydraulic system for the oil pumping unit of the present invention.

[0031] Key reference numerals:

[0032] 1. Servo motor; 2. Coupling; 3. Bidirectional pump motor; 31. First oil port of pump motor; 32. Second oil port of pump motor; 33. Third oil port of pump motor; 4. First check valve; 5. Second check valve; 6. First relief valve; 7. Second relief valve; 8. First hydraulically controlled check valve; 9. Second hydraulically controlled check valve; 10. Two-position four-way solenoid directional valve; 11. Flow meter; 12. First pressure relay; 13. Second pressure relay; 14. Hydraulic cylinder; 15. Speed ​​sensor; 16. Displacement sensor; 17. 18. Force sensor; 19. Energy storage device; 20. Third pressure relay; 21. Valve block; 22. High-pressure channel; 23. Low-pressure channel; 24. High-pressure oil circuit; 25. Low-pressure oil circuit; 26. Oil drain channel; 27. Motion controller; 28. Driver; 29. ​​DC bus; 30. Supercapacitor; A. Power supply; B. Oil replenishment module; C. Safety overflow module; D. Balance compensation module; E. Safety unloading module; F. Parameter detection module; G. Actuator module; H. Drive control module. Detailed Implementation

[0033] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0034] This invention provides a pump-controlled energy-saving oil pumping unit system based on DC bus capacitor energy storage, such as... Figure 1 and Figure 2 As shown, it includes a power module A, an oil replenishment module B, a safety overflow module C, a balance compensation module D, a safety unloading module E, a parameter detection module F, an actuator module G, and a drive control module H. The power module A includes a servo motor 1, a coupling 2, and a bidirectional pump motor 3. The servo motor 1 and the bidirectional pump motor 3 are connected by the coupling 2. The bidirectional pump motor 3 has a first oil port 31, a second oil port 32, and a third oil port 33.

[0035] The oil replenishment module B includes a first check valve 4, a second check valve 5, an accumulator 18, a third pressure relay 19, and a valve block 20. The first check valve 4 is connected to the first oil port 31 of the pump motor and the second check valve 5. The accumulator 18 is connected to the second check valve 5 and the second oil port 32 of the pump motor, and is also connected to the third pressure relay 19. In addition, the third oil port 33 of the pump motor is connected to the second check valve 5. The safety overflow module C includes a first overflow valve 6 and a second overflow valve 7. The first overflow valve 6 is connected to the first check valve 4 and the second overflow valve 7, and the second overflow valve 7 is connected to the second check valve 5.

[0036] The balance compensation module D includes a first hydraulically controlled check valve 8 and a second hydraulically controlled check valve 9. The first hydraulically controlled check valve 8 is connected to the first relief valve 6, and the second hydraulically controlled check valve 9 is connected to the second relief valve 7. The first hydraulically controlled check valve 8 is connected to the second hydraulically controlled check valve 9. At the same time, the control oil circuit of the first hydraulically controlled check valve 8 is connected to the low-pressure channel 22, and the control oil circuit of the second hydraulically controlled check valve 9 is connected to the high-pressure channel 21.

[0037] The safety unloading module E is configured as a two-position four-way solenoid directional valve 10, which is simultaneously connected to a first hydraulically controlled check valve 8 and a second hydraulically controlled check valve 9. The parameter detection module F includes a flow meter 11, a first pressure relay 12, and a second pressure relay 13. The flow meter 11 is connected to both the first pressure relay 12 and the two-position four-way solenoid directional valve 10, and the second pressure relay 13 is connected to the two-position four-way solenoid directional valve 10. The actuator module G includes a hydraulic cylinder 14, a speed sensor 15, a displacement sensor 16, and a force sensor 17. The hydraulic cylinder 14 is connected to both the flow meter 11 and the two-position four-way solenoid directional valve 10.

[0038] The drive control module H includes a motion controller 26, a driver 27, and a supercapacitor 29. The motion controller 26 is connected to the servo motor 1, the flow meter 11, the first pressure relay 12, the second pressure relay 13, the speed sensor 15, the displacement sensor 16, and the force sensor 17 via wires. The motion controller 26 is connected to the driver 27 via a wiring harness, and the driver 27 is connected to the servo motor 1 via wires. The driver 27 is connected to the power supply 30 via wires, and the driver 27 is connected to the supercapacitor 29 via a DC bus 28.

[0039] Furthermore, the first port of the first check valve 4 is connected to the first port 31 of the pump motor, the second port of the first check valve 4 is connected to the second port of the second check valve 5, the first port of the second check valve 5 is connected to the second port 32 of the pump motor, and the second port of the second check valve 5 is connected to the port of the accumulator 18. The port of the accumulator 18 is connected to the third pressure relay 19, the third port 33 of the pump motor is connected to the second port of the second check valve 5, and the accumulator 18 is connected to the drain channel 25. The first port of the first relief valve 6 is connected to the first port of the first check valve 4, the first port of the second relief valve 7 is connected to the first port of the second check valve 5, the second port of the first relief valve 6 is connected to the second port of the second relief valve 7, and the second port of the first relief valve 6 is connected to the second port of the first check valve 4.

[0040] The first port of the first hydraulically controlled check valve 8 is connected to the first port of the first relief valve 6 via the high-pressure channel 21. The first port of the second hydraulically controlled check valve 9 is connected to the first port of the second relief valve 7 via the high-pressure channel 21. The second port of the first hydraulically controlled check valve 8 is connected to the second port of the second hydraulically controlled check valve 9, and the second port of the first hydraulically controlled check valve 8 is also connected to the second port of the first relief valve 6. Simultaneously, the control oil circuit of the first hydraulically controlled check valve 8 is connected to the low-pressure channel 22, and the control oil circuit of the second hydraulically controlled check valve 9 is connected to the high-pressure channel 21. The first port of the two-position four-way solenoid directional valve 10 is connected to the first port of the first hydraulically controlled check valve 8, and the second port of the two-position four-way solenoid directional valve 10 is connected to the first port of the second hydraulically controlled check valve 9. The first port of the flow meter 11 is connected to the first pressure relay 12, the second port of the flow meter 11 is connected to the fourth port of the two-position four-way solenoid directional valve 10, and the second pressure relay 13 is connected to the third port of the two-position four-way solenoid directional valve 10. The first oil chamber of the hydraulic cylinder 14 is connected to the first oil port of the flow meter 11, and the second oil chamber of the hydraulic cylinder 14 is connected to the third oil port of the two-position four-way solenoid directional valve 10. The speed sensor 15, the displacement sensor 16 and the force sensor 17 are mounted on the hydraulic cylinder 14.

[0041] On the other hand, the present invention provides an energy recovery control method for a pump-controlled energy-saving oil pumping unit system based on DC bus capacitor energy storage, such as... Figure 3 As shown, it includes the following steps:

[0042] S1: Detect the maximum voltage U at terminal 29 of the supercapacitor. SCmax Minimum voltage U at terminal 29 of the supercapacitor SCmin and the working terminal voltage U of the supercapacitor 29 SC .

[0043] S2: Determine the operating condition of servo motor 1. If servo motor 1 is in generator operating condition, calculate the current state of charge (SOC) of supercapacitor 29 and execute step S3. If servo motor 1 is in motor operating condition or standby operating condition, execute step S4.

[0044] S3: Determine whether the current state of charge (SOC) of supercapacitor 29 has reached its maximum value. If the SOC of supercapacitor 29 has not reached its maximum value, charge supercapacitor 29 until it reaches its maximum SOC value. If the SOC of supercapacitor 29 has reached its maximum value, stop charging supercapacitor 29. At this time, supercapacitor 29 waits to discharge and executes step S1.

[0045] S4: Determine whether servo motor 1 is in motor mode. If servo motor 1 is in motor mode, proceed to step S5. If servo motor 1 is in standby mode, end the control.

[0046] S5: Determine whether the current state of charge (SOC) of supercapacitor 29 has reached its maximum value. If the SOC of supercapacitor 29 has reached its maximum value, proceed to step S6. If the SOC of supercapacitor 29 has not reached its maximum value, proceed to step S2.

[0047] S6: Supercapacitor 29 discharges, working in conjunction with power supply 30 to power servo motor 1.

[0048] S7: Determine whether the State of Charge (SOC) of supercapacitor 29 has reached the minimum value. If it has reached the minimum value, supercapacitor 29 stops discharging and waits to be charged, then proceed to step S1. If it has not reached the minimum value, return to step S6.

[0049] Furthermore, in step S2, the formula for calculating the State of Charge (SOC) of the supercapacitor 29 is as follows:

[0050]

[0051] Among them, U SCmax U is the maximum voltage at terminal 29 of the supercapacitor. SCmin U is the minimum voltage at terminal 29 of the supercapacitor. SC This is the operating voltage of supercapacitor 29.

[0052] In addition, to avoid overcharging and over-discharging of the supercapacitor 29, the maximum and minimum values ​​of the state of charge (SOC) of the supercapacitor 29 are 0.9 and 0.45, respectively.

[0053] Specifically, during operation, the 2-position 4-way solenoid directional valve 10 is in the right position. When the hydraulic cylinder 14 is lifted, the servo motor 1 drives the bidirectional pump motor 3 to rotate. At this time, the bidirectional pump motor 3 is in pump mode. The hydraulic oil passes through the second outlet of the bidirectional pump motor 3, and sequentially through the low-pressure channel 22, the 2-position 4-way solenoid directional valve 10, and the low-pressure oil circuit 24 into the rodless chamber of the hydraulic cylinder 14, pushing the hydraulic cylinder 14 upward. At the same time, the hydraulic oil in the rod chamber, pushed by the piston, sequentially passes through the high-pressure oil circuit 23, the 2-position 4-way solenoid directional valve 10, and the low-pressure oil circuit 24. The four-way solenoid directional valve 10, high-pressure channel 21, and pump motor first port 31 complete the circulation. When the hydraulic cylinder 14 descends under its own weight, the bidirectional pump motor 3 is in motor mode. Under the action of gravity, the hydraulic oil in the rodless chamber is pushed by the piston through the low-pressure oil circuit 24, the two-position four-way solenoid directional valve 10, and the low-pressure channel 22, and then through the pump motor second port 32 to drive the bidirectional pump motor 3 to rotate. Afterwards, it flows into the rod chamber through the high-pressure channel 21, the two-position four-way solenoid directional valve 10, and the high-pressure oil circuit 23. When an emergency stop or unloading is required, the two-position four-way solenoid directional valve 10 is in the normal position. At this time, the pressure oil pumped out by the pump motor second port 32 flows back to the pump motor first port 31 through the low-pressure channel 22, the two-position four-way solenoid directional valve 10, and the high-pressure channel 21. At this time, the hydraulic cylinder 14 is locked in the current position to ensure the safety of the personnel.

[0054] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A pump-controlled energy-saving oil pumping unit system based on DC bus capacitor energy storage, characterized in that: It includes a power module, a refueling module, a safety overflow module, a balance compensation module, a safety unloading module, a parameter detection module, an actuator module, and a drive control module. The power module includes a servo motor and a bidirectional pump motor; the oil replenishment module includes a first check valve, a second check valve, an energy accumulator, and a third pressure relay; the safety overflow module includes a first overflow valve and a second overflow valve; the balance compensation module includes a first hydraulically controlled check valve and a second hydraulically controlled check valve; the safety unloading module is configured as a two-position four-way solenoid directional valve; the parameter detection module includes a flow meter, a first pressure relay, and a second pressure relay; the actuator module includes a hydraulic cylinder, a speed sensor, a displacement sensor, and a force sensor; and the drive control module includes a motion controller, a driver, and a supercapacitor. The first check valve and the second check valve are connected and both are connected to the bidirectional pump motor. The first relief valve and the second relief valve are connected and both are connected to the bidirectional pump motor. The first hydraulically controlled check valve and the second hydraulically controlled check valve are respectively connected to the first relief valve. The second hydraulically controlled check valve is connected to the second relief valve. The two-position four-way solenoid directional valve is respectively connected to the first hydraulically controlled check valve, the second hydraulically controlled check valve, the flow meter, the hydraulic cylinder, and the second pressure relay. The flow meter is respectively connected to the first pressure relay and the hydraulic cylinder. The motion controller is connected to the driver, servo motor, flow meter, first pressure relay, second pressure relay, speed sensor, displacement sensor and force sensor respectively. The driver is connected to the servo motor and power supply. The driver and supercapacitor are connected through a DC bus. The bidirectional pump motor is equipped with a first oil port, a second oil port and a third oil port. The first oil port is connected to a first check valve, the second oil port is connected to a second check valve, and the third oil port is connected to a low-pressure channel. The servo motor and the bidirectional pump motor are connected by a coupling. The speed sensor, displacement sensor, and force sensor are mounted on the hydraulic cylinder and connected to the motion controller via wires. The control oil circuit of the first hydraulic check valve is connected to the low-pressure channel, and the control oil circuit of the second hydraulic check valve is connected to the high-pressure channel. The accumulator is connected to the second one-way valve and the two-way pump motor. The accumulator is also connected to the oil drain channel. A third pressure relay is installed at the oil port of the accumulator.

2. A control method for the pump-controlled energy-saving oil pumping unit system based on DC bus capacitor energy storage as described in claim 1, characterized in that, It includes the following steps: S1: Detects the maximum, minimum, and operating terminal voltages of the supercapacitor. S2: Determine the servo motor's operating condition. If it is in generator mode, calculate the current supercapacitor's state of charge. SOC Then execute step S3; if it is motor operating condition or standby condition, then execute step S4. S3: Determine the state of charge SOC If the current value is reached, charging the supercapacitor stops; otherwise, charging continues until the supercapacitor reaches its state of charge. SOC Find the maximum value and proceed to step S4; S4: Determine if the servo motor is in motor operation mode. If yes, proceed to step S5. If it is in standby mode, end the process. S5: Determine the state of charge SOC Is it the maximum value? If yes, proceed to step S6; otherwise, proceed to step S2. S6: The supercapacitor discharges and works with the power supply to power the servo motor. S7: Determine the state of charge of the supercapacitor SOC If the value is the minimum, the supercapacitor stops discharging and waits to be charged, then proceed to step S1; otherwise, return to step S6.

3. The control method for a pump-controlled energy-saving oil pumping unit system based on DC bus capacitor energy storage according to claim 2, characterized in that: In step S2, the supercapacitor's state of charge... SOC The calculation formula is: ; In the formula, U SCmax This represents the maximum terminal voltage of the supercapacitor. U SCmin This represents the minimum terminal voltage of the supercapacitor. U SC This is the operating voltage of the supercapacitor.

4. The control method for a pump-controlled energy-saving oil pumping unit system based on DC bus capacitor energy storage according to claim 2 or 3, characterized in that: State of charge of supercapacitors SOC The maximum and minimum values ​​are 0.9 and 0.45, respectively.

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