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

Abstract

The invention provides a pump control energy-saving oil pumping unit system based on direct current bus capacitor energy storage and a control method, and relates to the field of oil pumping units, the system comprises a power module, an oil supplementing module, a safe overflow module, a balance compensation module, a safe unloading module, a parameter detection module, an execution mechanism module and a drive control module, and the gravitational potential energy of the load is recycled. The control method comprises the steps of detecting the voltage of the super capacitor and the voltage of the working end, calculating the current state of charge SOC, judging whether the current state of charge SOC is the maximum value or not, judging the working condition of the servo motor, charging and discharging the super capacitor, storing energy or providing energy for the system. According to the system, throttling overflow loss is avoided, the servo motor is used for driving the pump motor to serve as a power source for gravitational potential energy generated in the working process of the oil pumping unit, the generated gravitational potential energy is recycled, the utilization efficiency of system energy is improved, and meanwhile multiple working conditions such as sudden stop, unloading and pressure maintaining can be achieved only through one two-position four-way electromagnetic directional valve.

Description

Technical Field

[0001] The present invention belongs to the technical field of pumping units, and particularly relates to a pump-controlled energy-saving pumping unit system based on DC bus capacitor energy storage and a control method therefor. Background Art

[0002] As a strategic reserve energy source, petroleum has a profound impact on a country's economy, security, and development. Pumping units play a very important role in the process of oil extraction. Most of the existing pumping units use traditional valve control systems, which have large throttling and overflow losses, resulting in low efficiency and high energy consumption during oil production. Moreover, the traditional valve control system requires auxiliary equipment such as an oil tank and a cooling tower during operation, which requires a large floor area and has a great impact on the actual mining process.

[0003] Therefore, it is necessary to propose a new pump-controlled hydraulic system for pumping units and an energy recovery control method to solve the above defects. Summary of the Invention

[0004] In order to solve the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a pump-controlled energy-saving pumping unit system based on DC bus capacitor energy storage and a control method therefor. Compared with the traditional valve control system, it has no throttling and overflow losses, does not require an oil tank and a cooling tower as auxiliary equipment, has high efficiency and a small floor area. The present invention uses a servo motor to drive a pump motor as a power source to recover and utilize the gravitational potential energy generated during the operation of the pumping unit, reduces the system energy consumption, and improves the energy utilization efficiency of the system.

[0005] Specifically, on the one hand, the present invention provides a pump-controlled energy-saving pumping unit system based on DC bus capacitor energy storage, which includes a power module, a supplementary oil 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 supplementary oil module includes a first one-way valve, a second one-way valve, an 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 hydraulic control one-way valve and a second hydraulic control one-way valve. The safety unloading module is set as a two-position four-way electromagnetic 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. The drive control module includes a motion controller, a driver, and a super capacitor.

[0006] The first one-way valve is connected to the second one-way 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 pilot-operated one-way valve is connected to the second pilot-operated one-way valve and the first relief valve. The second pilot-operated one-way valve is connected to the second relief valve. The two-position four-way electromagnetic directional valve is connected to the first pilot-operated one-way valve, the second pilot-operated one-way valve, the flowmeter, the hydraulic cylinder, and the second pressure relay. The flowmeter is connected to the first pressure relay and the hydraulic cylinder.

[0007] The motion controller is connected to the driver, the servo motor, the flowmeter, the first pressure relay, the second pressure relay, the speed sensor, the displacement sensor, and the force sensor. The driver is connected to the servo motor and the power supply. The driver is connected to the super capacitor through the DC bus.

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

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

[0010] Preferably, the control oil circuit of the first pilot-operated one-way valve is connected to the low-pressure passage, and the control oil circuit of the second pilot-operated one-way valve is connected to the high-pressure passage.

[0011] Preferably, the energy storage device is connected to the second one-way valve and the bidirectional pump motor. The energy storage device is connected to the oil drain passage. A third pressure relay is installed at the oil port of the energy storage device.

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

[0013] S1: Detect the maximum value of the super capacitor terminal voltage, the minimum value of the voltage, and the working terminal voltage;

[0014] S2: Judge the working condition of the servo motor. If it is in the generator working condition, calculate the current state of charge SOC of the super capacitor and execute step S3. If it is in the motor working condition or the standby working condition, execute step S4;

[0015] S3: Judge whether the state of charge SOC is the maximum value. If it is, stop charging the super capacitor. If not, charge the super capacitor until the maximum value of the state of charge SOC is reached, and execute step S4;

[0016] S4: Judge whether the servo motor is in the motor working condition. If it is, execute step S5. If it is in the standby state, end;

[0017] S5: Determine whether the state of charge (SOC) is the maximum value. If so, execute step S6; if not, execute step S2.

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

[0019] S7: Determine whether the state of charge (SOC) of the supercapacitor is the minimum value. If so, the supercapacitor stops discharging, waits for charging, and executes step S1; if not, return to step S6.

[0020] Preferably, in step S2, the calculation formula for the state of charge (SOC) of the supercapacitor is

[0021]

[0022] In the formula, U SCmax is the maximum value of the terminal voltage of the supercapacitor, U SCmin is the minimum value of the terminal voltage of the supercapacitor, and U SC is the working terminal voltage of the supercapacitor.

[0023] Furthermore, preferably, to avoid overcharging and over-discharging of the supercapacitor, the maximum and minimum values of the state of charge (SOC) of the supercapacitor 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. Compared with the traditional valve-controlled hydraulic system, there is no throttling and overflow loss, the power-to-weight ratio is large, the efficiency is high. Compared with the traditional valve-controlled hydraulic system, the volume of the fuel tank is greatly reduced, the floor area 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. Only one two-position four-way electromagnetic directional valve can be used to achieve multiple working conditions such as emergency stop, unloading, and pressure holding. Compared with the traditional system, the number of failure points is reduced, it is easy to operate, and the cost can be significantly reduced at the same time.

[0027] (3) The present invention uses a servo motor to coaxially drive a variable pump. The hydraulic pump has the ability to work in four quadrants. In the pump working condition, it outputs flow, controls the position, speed, and output force of the hydraulic cylinder, and consumes energy at this time. When the pumping unit has an overloading condition and the pump working condition is converted to the motor working condition, the servo motor functions as a generator, the bus voltage rises, and the supercapacitor stores electrical energy, and feeds energy at this time. In the next energy-consuming working condition, the electrical energy stored in the supercapacitor is utilized, improving the energy utilization efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is the schematic diagram of the closed pump-controlled hydraulic system of the pumping unit of the present invention.

[0029] Figure 2 Schematic diagram of the functional blocks of the closed - loop pump - controlled hydraulic system of the pumping unit of the present invention;

[0030] Figure 3 Flow chart of the control strategy of the closed - loop pump - controlled hydraulic system of the pumping unit of the present invention.

[0031] Main reference numerals:

[0032] 1. Servo motor; 2. Coupling; 3. Bidirectional pump - motor; 31. First oil port of the pump - motor; 32. Second oil port of the pump - motor; 33. Third oil port of the pump - motor; 4. First check valve; 5. Second check valve; 6. First relief valve; 7. Second relief valve; 8. First hydraulic control check valve; 9. Second hydraulic control check valve; 10. Two - position four - way solenoid directional control valve; 11. Flowmeter; 12. First pressure relay; 13. Second pressure relay; 14. Hydraulic cylinder; 15. Speed sensor; 16. Displacement sensor; 17. Force sensor; 18. Accumulator; 19. Third pressure relay; 20. Valve block; 21. High - pressure passage; 22. Low - pressure passage; 23. High - pressure oil circuit; 24. Low - pressure oil circuit; 25. Drainage passage; 26. Motion controller; 27. Driver; 28. DC bus; 29. Super capacitor; 30. Power supply; A. Power module; B. Oil - replenishing 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 manners

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

[0034] The present invention provides a pump - controlled energy - saving pumping unit system based on DC - bus capacitor energy storage, as shown in Figure 1 and Figure 2 which includes a power module A, an oil - replenishing 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 is provided with a first oil port 31 of the pump - motor, a second oil port 32 of the pump - motor, and a third oil port 33 of the pump - motor.

[0035] The oil replenishment module B includes a first one-way valve 4, a second one-way valve 5, an accumulator 18, a third pressure relay 19, and a valve block 20. The first one-way valve 4 is connected to the first oil port 31 of the pump motor and the second one-way valve 5. While the accumulator 18 is connected to the second one-way valve 5 and the second oil port 32 of the pump motor, it 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 one-way 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 one-way valve 4 and the second overflow valve 7, and the second overflow valve 7 is connected to the second one-way valve 5.

[0036] The balance compensation module D includes a first pilot-operated one-way valve 8 and a second pilot-operated one-way valve 9. The first pilot-operated one-way valve 8 is connected to the first overflow valve 6, and the second pilot-operated one-way valve 9 is connected to the second overflow valve 7. The first pilot-operated one-way valve 8 is connected to the second pilot-operated one-way valve 9. At the same time, the control oil circuit of the first pilot-operated one-way valve 8 is connected to the low-pressure passage 22, and the control oil circuit of the second pilot-operated one-way valve 9 is connected to the high-pressure passage 21.

[0037] The safety unloading module E is set as a two-position four-way solenoid directional valve 10, and the two-position four-way solenoid directional valve 10 is connected to both the first pilot-operated one-way valve 8 and the second pilot-operated one-way valve 9. The parameter detection module F includes a flowmeter 11, a first pressure relay 12, and a second pressure relay 13. The flowmeter 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 flowmeter 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 super capacitor 29. The motion controller 26 is respectively connected to the servo motor 1, the flowmeter 11, the first pressure relay 12, the second pressure relay 13, the speed sensor 15, the displacement sensor 16, and the force sensor 17 through wires. The motion controller 26 is connected to the driver 27 through a wire harness, and the driver 27 is connected to the servo motor 1 through a wire. The driver 27 is connected to the power supply 30 through a wire, and the driver 27 is connected to the super capacitor 29 through a DC bus 28.

[0039] Further, the first oil port of the first one-way valve 4 is connected to the first oil port 31 of the pump motor, the second oil port of the first one-way valve 4 is connected to the second oil port of the second one-way valve 5, the first oil port of the second one-way valve 5 is connected to the second oil port 32 of the pump motor. At the same time, the second oil port of the second one-way valve 5 is connected to the oil port of the accumulator 18, the oil port of the accumulator 18 is connected with a third pressure relay 19, the third oil port 33 of the pump motor is connected to the second oil port of the second one-way valve 5, and the accumulator 18 is connected to the oil drain passage 25. The first oil port of the first overflow valve 6 is connected to the first oil port of the first one-way valve 4, the first oil port of the second overflow valve 7 is connected to the first oil port of the second one-way valve 5, the second oil port of the first overflow valve 6 is connected to the second oil port of the second overflow valve 7, and the second oil port of the first overflow valve 6 is connected to the second oil port of the first one-way valve 4.

[0040] The first oil port of the first hydraulic control one-way valve 8 is connected to the first oil port of the first overflow valve 6 through a high-pressure passage 21, the first oil port of the second hydraulic control one-way valve 9 is connected to the first oil port of the second overflow valve 7 through a high-pressure passage 21, the second oil port of the first hydraulic control one-way valve 8 is connected to the second oil port of the second hydraulic control one-way valve 9, and the second oil port of the first hydraulic control one-way valve 8 is connected to the second oil port of the first overflow valve 6. At the same time, the control oil passage of the first hydraulic control one-way valve 8 is connected to a low-pressure passage 22, and the control oil passage of the second hydraulic control one-way valve 9 is connected to the high-pressure passage 21. The first oil port of the two-position four-way electromagnetic reversing valve 10 is connected to the first oil port of the first hydraulic control one-way valve 8, and the second oil port of the two-position four-way electromagnetic reversing valve 10 is connected to the first oil port of the second hydraulic control one-way valve 9. The first oil port of the flowmeter 11 is connected to the first pressure relay 12, the second oil port of the flowmeter 11 is connected to the fourth oil port of the two-position four-way electromagnetic reversing valve 10, and the second pressure relay 13 is connected to the third oil port of the two-position four-way electromagnetic reversing valve 10. The first oil chamber of the hydraulic cylinder 14 is connected to the first oil port of the flowmeter 11, the second oil chamber of the hydraulic cylinder 14 is connected to the third oil port of the two-position four-way electromagnetic reversing valve 10, and the speed sensor 15, displacement sensor 16 and force sensor 17 are arranged 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 pumping unit system based on DC bus capacitor energy storage, as Figure 3 shown, which includes the following steps:

[0042] S1: Detect the maximum value U of the terminal voltage of the super capacitor 29 SCmax 、the minimum value U of the terminal voltage of the super capacitor 29 SCmin and the working terminal voltage U of the super capacitor 29 SC .

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

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

[0045] S4: Determine whether the servo motor 1 is in the motor operating condition. If the servo motor 1 is in the motor operating condition, execute step S5. If the servo motor 1 is in the standby state, end the control.

[0046] S5: Determine whether the state of charge (SOC) of the current supercapacitor 29 has reached the maximum value. If the state of charge (SOC) of the supercapacitor 29 reaches the maximum value at this time, execute step S6. If the state of charge (SOC) of the supercapacitor 29 has not reached the maximum value at this time, execute step S2.

[0047] S6: The supercapacitor 29 discharges and supplies power to the servo motor 1 in cooperation with the power supply 30.

[0048] S7: Determine whether the state of charge (SOC) of the supercapacitor 29 has reached the minimum value. If it reaches the minimum value, the supercapacitor 29 stops discharging and waits for charging, and executes step S1. If it has not reached the minimum value, return to step S6.

[0049] Furthermore, in step S2, the calculation formula for the state of charge (SOC) of the supercapacitor 29 is as follows:

[0050]

[0051] where U SCmax is the maximum value of the terminal voltage of the supercapacitor 29, U SCmin is the minimum value of the terminal voltage of the supercapacitor 29, and U SC is the working terminal voltage of the 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 the working condition, the two-position four-way electromagnetic reversing 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 the pump condition. The hydraulic oil passes through the second oil outlet of the bidirectional pump motor 3, and then successively passes through the low-pressure passage 22, the two-position four-way electromagnetic reversing valve 10, and the low-pressure oil circuit 24 to enter the rodless cavity of the hydraulic cylinder 14, pushing the hydraulic cylinder 14 to move upward. At the same time, the hydraulic oil in the rod cavity is pushed by the piston and successively passes through the high-pressure oil circuit 23, the two-position four-way electromagnetic reversing valve 10, the high-pressure passage 21, and the first oil port 31 of the pump motor to complete the cycle. When the hydraulic cylinder 14 descends under its own weight, at this time, the bidirectional pump motor 3 is in the motor condition. Under the action of gravity, the hydraulic oil in the rodless cavity is pushed by the piston and passes through the low-pressure oil circuit 24, the two-position four-way electromagnetic reversing valve 10, and the low-pressure passage 22, and then drives the bidirectional pump motor 3 to rotate through the second oil port 32 of the pump motor. After that, it flows into the rod cavity through the high-pressure passage 21, the two-position four-way electromagnetic reversing valve 10, and the high-pressure oil circuit 23. When emergency stop or unloading is required, the two-position four-way electromagnetic reversing valve 10 is in the normal position. At this time, the pressure oil pumped out from the second oil port 32 of the pump motor passes through the low-pressure passage 22, the two-position four-way electromagnetic reversing valve 10, and the high-pressure passage 21 and flows back to the first oil port 31 of the pump motor. And at this time, the hydraulic cylinder 14 is locked in the current position, ensuring the safety of the staff.

[0054] The above-described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A pump-controlled energy-saving pumping unit system based on DC bus capacitor energy storage, characterized in that: It 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 and a bidirectional pump motor. The oil replenishment module includes a first check valve, a second check valve, an accumulator, and a third pressure relay. The safety overflow module includes a first relief valve and a second relief valve. The balance compensation module includes a first pilot-operated check valve and a second pilot-operated check valve. The safety unloading module is set as a two-position four-way solenoid directional control valve. The parameter detection module includes a flowmeter, 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. The drive control module includes a motion controller, a driver, and a super capacitor. 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 pilot-operated check valve and the second pilot-operated check valve are respectively connected to the first relief valve. The second pilot-operated check valve is connected to the second relief valve. The two-position four-way solenoid directional control valve is respectively connected to the first pilot-operated check valve, the second pilot-operated check valve, the flowmeter, the hydraulic cylinder, and the second pressure relay. The flowmeter is respectively connected to the first pressure relay and the hydraulic cylinder. The motion controller is respectively connected to the driver, the servo motor, the flowmeter, the first pressure relay, the second pressure relay, the speed sensor, the displacement sensor, and the force sensor. The driver is connected to the servo motor and the power supply. The driver and the super capacitor are connected through a DC bus.

2. The pump-controlled energy-saving pumping unit system based on DC bus capacitor energy storage according to claim 1, wherein: The bidirectional pump motor is provided with a first pump motor oil port, a second pump motor oil port, and a third pump motor oil port. The first pump motor oil port is connected to the first check valve. The second pump motor oil port is connected to the second check valve. The third pump motor oil port is connected to a low-pressure passage. The servo motor and the bidirectional pump motor are connected through a coupling.

3. The pump-controlled energy-saving pumping unit system based on DC bus capacitor energy storage according to claim 1, characterized in that: The speed sensor, the displacement sensor, and the force sensor are installed on the hydraulic cylinder and are respectively connected to the motion controller through wires.

4. The pump-controlled energy-saving pumping unit system based on DC bus capacitor energy storage according to claim 1, characterized in that: The control oil passage of the first pilot-operated check valve is connected to the low-pressure passage. The control oil passage of the second pilot-operated check valve is connected to the high-pressure passage.

5. The pump-controlled energy-saving pumping unit system based on DC bus capacitor energy storage according to claim 1, wherein: The accumulator is connected to the second check valve and the bidirectional pump motor. The accumulator is connected to a drain passage. A third pressure relay is installed at the oil port of the accumulator.

6. A control method for the pump-controlled energy-saving pumping unit system based on DC bus capacitor energy storage according to claim 1, characterized in that, It includes the following steps: S1: Detect the maximum value of the super capacitor terminal voltage, the minimum value of the voltage, and the working terminal voltage. S2: Judge the working condition of the servo motor. If it is in the generator working condition, calculate the current state of charge (SOC) of the super capacitor and execute step S3. If it is in the motor working condition or the standby working condition, execute step S4. S3: Judge whether the state of charge (SOC) is the maximum value. If it is, stop charging the super capacitor. If not, charge the super capacitor until the maximum value of the state of charge (SOC) is reached, and then execute step S4. S4: Judge whether the servo motor is in the motor working condition. If it is, execute step S5. If it is in the standby state, end. S5: Judge whether the state of charge (SOC) is the maximum value. If it is, execute step S6. If not, execute step S2. S6: The super capacitor discharges and supplies power to the servo motor in cooperation with the power supply. S7: Determine whether the state of charge (SOC) of the supercapacitor is at its minimum value. If it is, the supercapacitor stops discharging and waits to be charged, and step S1 is executed. If not, return to step S6.

7. The control method of the pump-controlled energy-saving pumping unit system based on DC bus capacitor energy storage according to claim 6, characterized in that: In step S2, the calculation formula for the state of charge (SOC) of the supercapacitor is Where, U SCmax is the maximum voltage of the super capacitor terminal, U SCmin is the minimum voltage of the super capacitor terminal, and U SC is the working voltage of the super capacitor terminal.

8. The control method of the pump-controlled energy-saving pumping unit system based on DC bus capacitor energy storage according to claim 6 or 7, characterized in that: The maximum and minimum values of the state of charge (SOC) of the supercapacitor are 0.9 and 0.45 respectively.

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