CN100411299C - Energy saving control method and control device for asynchronous motor of beam pumping unit - Google Patents

Abstract

The invention relates to an energy-saving control method and a control device for an asynchronous motor of a beam pumping unit. The control method includes steps: 1. Collecting the operating parameters of the asynchronous motor; 2. Disconnecting the asynchronous motor from the power grid when it enters the power generation state; 3. The asynchronous motor and the no-load excitation capacitor form an island power generation system, and collect the operating parameters of the asynchronous motor; 4. , When the asynchronous motor enters the electric state, connect it to the grid. The control device includes a first switch assembly connected to the asynchronous motor and the AC power circuit, a drive unit, a computer controller and a data acquisition unit connected to the first switch assembly in sequence, and an unloaded excitation capacitor connected to the asynchronous motor. The invention comprehensively considers the elimination of reverse power generation phenomenon and reactive power compensation, not only completely eliminates the reverse power generation phenomenon of the asynchronous motor, but also makes full use of the power generated by the asynchronous motor for speed measurement, and at the same time performs reactive power compensation in the electric state of the asynchronous motor. The best energy-saving solution.

Description

Energy saving control method and control device for asynchronous motor of beam pumping unit

technical field

The invention relates to the field of petroleum exploitation machinery, in particular to an energy-saving control method and a control device for an asynchronous motor of a beam pumping unit based on an island power generation technology.

Background technique

Beam pumping unit (commonly known as kowtow pumping unit) is a kind of oil production machinery with large energy consumption widely used in oilfield systems, and its electricity expense accounts for more than 60% of the total expenditure of oil production system. The energy consumed by the lifting and lowering of the sucker rod's own weight can be reduced to almost zero in theory, but this is not the case in actual use. The pumping unit powered by asynchronous motor has a "strong" constant torque characteristic. When the speed of the rotor of the asynchronous motor exceeds the synchronous speed of the motor, the net torque of the crank is negative, and the asynchronous motor will become an asynchronous generator to send power to the grid. Commonly known as "reverse power generation". It is common for the rotor of the asynchronous motor to exceed the synchronous speed. Even if the balance weight of the pumping unit is carefully adjusted, the phenomenon of "reverse power generation" is almost inevitable due to various factors. Part of the electric energy generated by the generator is lost in the primary and secondary windings of the transformer and the feeder line, and the rest is expressed as pulsating power output to the power system. Since the electricity generated by the asynchronous motor will not be fully synchronized with the grid, its electric energy will not be fully utilized by the grid, so this pulsating power is an interference and pollution to the grid. Therefore, eliminating the phenomenon of "backward power generation" has very important energy-saving significance.

There are many methods to solve the problem of "inverted power generation" in the existing technology, such as ultra-high slip motors, voltage regulator controllers, frequency converters, etc., but these methods can only reduce the degree of "inverted power generation" and cannot completely eliminate " The phenomenon of "inverting power generation" is not suitable for the transformation of old oil wells and the implementation cost is high.

In the prior art, there is a technical solution of adopting an overrunning clutch to solve "backward power generation". The working principle of this technical solution is: when pumping oil upwards, the clutch connects the drag wheel (connected to the asynchronous motor shaft) and the driven wheel (connected to the sucker rod) to rotate together; When the rotation speed of the asynchronous motor is greater than that, the clutch separates the driving wheel from the driven wheel, so that the asynchronous motor is always in the electric state, avoiding the reverse power generation of the asynchronous motor when descending, thereby improving the power supply quality of the grid and saving energy. Although this technical solution separates the drag wheel from the driven wheel, the asynchronous motor is still connected to the AC power supply, and the asynchronous motor still produces additional no-load loss. In addition, this technical solution is neither suitable for the transformation of old oil wells, and the initial investment of new oil wells is large, and because of the gear meshing, the maintenance of the pumping unit is also relatively difficult.

In the prior art, there is also a technical solution to solve "inverted power generation" by using intermittent power supply of asynchronous motors. The working principle of the technical solution is: when the measured speed exceeds the critical speed, the asynchronous motor is controlled to be powered on for a period of time, and then continue to be powered off. Then judge the speed, if the speed is too high, then make the asynchronous motor run with power for a period of time, and then continue to cut off the power.... Although this technical solution keeps the speed of the asynchronous motor in the normal range through intermittent power supply, power outage process and adjustment of power outage time and number of power outages, it does not completely solve the problem of "reverse power generation". Instead, the accumulated reverse power generation energy is frequently Centralized release to the grid. In fact, this would cause more harm to the system and the grid.

The low power factor of the asynchronous motor of the beam pumping unit is another large loss. How to reduce the loss of the asynchronous motor and improve the power factor of the power distribution system has become another key to energy saving in the oil field. Therefore, in the beam pumping unit The use of fixed capacitors for compensation on pumping units is an energy-saving measure commonly adopted by major oil fields in China. Since the load of the beam pumping unit is a periodic load that continuously changes with the stroke of the pumping unit, the use of fixed capacitor compensation has both advantages and disadvantages, that is, it will make the pumping unit drag asynchronously The power generation effect of the motor is enhanced, which will bring new waste of electric energy.

To sum up, the problems existing in the existing beam pumping unit system mainly focus on the "inverted power generation" of the asynchronous motor and the low power factor, and no comprehensive and effective solution has been seen yet.

Contents of the invention

The first purpose of the present invention is to provide an energy-saving control method for the asynchronous motor of the beam pumping unit based on the isolated island power generation technology, which completely eliminates the dragging of the pumping unit. The phenomenon of "reverse power generation" of asynchronous motors; further, the present invention also aims at the technical problem of low power factor of motors in the prior art, and performs reactive power compensation in the electric state stage of asynchronous motors, which will eliminate the phenomenon of "reverse power generation" and reactive power compensation Consider comprehensively to achieve the best energy-saving effect.

The second object of the present invention is to provide an energy-saving control device for the asynchronous motor of the beam pumping unit based on the island power generation technology based on the energy-saving control method of the asynchronous motor of the beam pumping unit of the present invention.

In order to achieve the first purpose of the present invention, the present invention provides a method for energy-saving control of an asynchronous motor of a beam pumping unit, comprising the steps of:

Step 10, in the power-on running state of the asynchronous motor, the data acquisition unit collects the voltage and current instantaneous values of the asynchronous motor in real time during operation, and transmits the voltage and current data to the computer controller;

Step 20, when the computer controller judges that the asynchronous motor enters the power generation state according to the voltage and current data, output a control signal to the drive unit;

Step 30, the drive unit controls the first switch assembly to cut off the connection between the asynchronous motor and the AC power supply;

Step 40, the asynchronous motor and the no-load excitation capacitor form an island power generation system, and the data acquisition unit collects the instantaneous voltage and current values of the asynchronous motor in the island power generation system in real time, and transmits the voltage and current data to the computer controller;

Step 50, the computer controller judges that the asynchronous motor enters the motoring state according to the voltage and current data of the asynchronous motor in the island power generation system, and outputs a control signal to the drive unit;

Step 60, the drive unit controls the first switch assembly to restore the connection between the asynchronous motor and the AC power supply.

Wherein, the step 20 is specifically:

Step 201, the computer controller calculates the active power value of the asynchronous motor according to the voltage and current data;

Step 202, when the active power value is less than the power preset value, the computer controller judges that the asynchronous motor starts to enter the power generation state;

Step 203, the computer controller outputs a control signal to the drive unit.

Wherein, the step 50 is specifically:

Step 501, the soft instrument unit of the computer controller calculates the speed of the asynchronous motor according to the voltage and current data of the asynchronous motor in the island power generation system;

Step 502, the computer controller calculates the difference between the rotational speed and the synchronous rotational speed of the asynchronous motor;

Step 503, when the difference is less than the preset difference, the computer controller judges that the asynchronous motor starts to enter the electric state;

Step 504, the computer controller outputs a control signal to the drive unit.

In the above technical solution, after step 30 and before step 40, a dummy load connected in series with the asynchronous motor and a step of controlling the speed of the asynchronous motor with a frequency stabilization and voltage stabilization circuit are specifically:

Step 31, the frequency stabilizing circuit automatically monitors the no-load voltage of the asynchronous motor;

Step 32. When the no-load voltage of the asynchronous motor is greater than the preset safety critical voltage, the thyristor of the frequency stabilizing circuit is turned on, and the dummy load consumes supercritical energy;

Step 33. When the no-load voltage of the asynchronous motor falls within the preset safety critical voltage range, the thyristor of the frequency stabilizing circuit is turned off.

In the above technical solution, after the step 60, it also includes the step of connecting the reactive power compensation capacitor in parallel to the AC power supply. Correspondingly, it also includes cutting off the reactive power compensation capacitor and the AC power supply after the step 20 and before the step 30 Steps to connect.

In order to achieve the second purpose of the present invention, the present invention also provides an energy-saving control device for the asynchronous motor of the beam pumping unit, which includes a first switch assembly connected to the asynchronous motor and the AC power circuit and an air switch assembly connected to the asynchronous motor. A magnetizing capacitor is carried, the first switch assembly is connected with a drive unit that controls its on or off, the drive unit is connected with a computer controller that sends a control signal for on or off, and the computer controller is connected with the A data acquisition unit for acquiring the instantaneous voltage and current values of the asynchronous motor is connected.

The computer controller includes a control unit and a soft instrument unit connected in series, and the instrument unit is connected to the data acquisition unit for calculating the rotational speed and active power value of the asynchronous motor according to the received voltage and current data, the The control unit is connected with the drive unit, and is used for judging the moment when the asynchronous motor enters the power generation or motoring state according to the active power or rotational speed value, and sends an off or on control signal to the drive unit.

In the above technical solution, the asynchronous motor is also connected with a series-connected dummy load and a frequency stabilizing circuit, the frequency stabilizing circuit is a bidirectional thyristor circuit with multi-block adjustment, and the dummy load is connected in series resistance and capacitance. The AC power supply is also connected in parallel with a second switch component and a reactive power compensation capacitor connected in series, and the second switch component is connected with the drive unit. The first switch assembly is an electronic voltage regulating switch and a mechanical switch connected in parallel, and the second switch assembly is an electronic switch and a mechanical switch connected in parallel, which are respectively connected to the drive unit.

The invention provides an energy-saving control method and a control device for an asynchronous motor of a beam pumping unit based on an isolated island power generation technology, and specifically solves the problems existing in the prior art from three aspects. First, it fundamentally eliminates the phenomenon of "reverse power generation" in the existing technology, realizing environmental protection and energy saving; second, it uses the energy generated by the asynchronous motor to measure the speed, and makes full use of the energy wasted by the existing technology; third, it uses automatic capacitors Compensate, improve the power factor of the asynchronous motor in the electric state, and realize the purpose of comprehensive energy saving under various working conditions of the present invention.

The technical characteristics of the energy-saving control method and control device of the asynchronous motor of the beam pumping unit based on the island power generation technology of the present invention are prominently reflected in the stage of the power generation state. On the one hand, the asynchronous motor is disconnected from the power grid; The excitation capacitor forms an island power generation system, and the no-load excitation capacitor acts as an excitation to generate no-load voltage, so that the computer controller can obtain the voltage and current data of the asynchronous motor through the data acquisition unit, thereby calculating the speed of the asynchronous motor, so that the asynchronous motor can be realized The judgment of the moment when the motor enters the electric state. The technical solution of the present invention is not only different from the simple power failure of the prior art, but also has essential differences from the prior art of clutching the shaft of the asynchronous motor and the sucker rod. The island power generation technology makes full use of the power generated by the asynchronous motor for data collection, turning the unfavorable factors of "inverting power generation" into favorable energy, thus realizing the energy saving effect to the greatest extent.

The present invention also proposes an optimal scheme for connecting the asynchronous motor to the pseudo load in series and the frequency and voltage stabilization circuit. When the speed of the asynchronous motor exceeds the safety critical speed, the energy stored in the asynchronous motor will be automatically released through the frequency stabilization and voltage stabilization circuit, and the The rotating speed is reduced to within the preset safety critical rotating speed range, which effectively solves the problem of out-of-control rotating speed of the asynchronous motor, and improves the implementability and reliability of the present invention.

The present invention further proposes an optimal technical scheme of connecting a reactive power compensation capacitor to the AC power supply circuit. When the asynchronous motor is in the motoring state, the reactive power compensation capacitor is automatically switched on, thereby improving the power factor of the asynchronous motor, so that the present invention can be used in various There are obvious energy-saving effects under all working conditions. When the asynchronous motor is in the power generation state, the reactive power compensation capacitor is automatically removed, which eliminates the technical defect that the reactive power compensation capacitor in the prior art enhances the power generation effect of the asynchronous motor and brings new waste of electric energy.

In the present invention, the first switch assembly adopts an electronic voltage regulating switch and a mechanical switch connected in parallel, and the second switch assembly adopts an electronic switch and a mechanical switch connected in parallel. , while the electronic voltage regulating switch is responsible for the cut off when the current crosses zero and the voltage gradually increases from zero to the rated value to prevent the overload current impact when it is put into operation, and the mechanical switch is connected when the asynchronous motor or capacitor is running normally. This solution can not only eliminate the new heat energy consumption caused by the operation of electronic switches alone, but also solve the problem of limited life due to frequent actions of mechanical switches alone, and at the same time reduce the system current impact, improve system operation reliability and further save energy.

The invention rationally designs the frequency stabilizing and voltage stabilizing circuit, adjusts in N gears, and controls the load to change from scratch, from small to large, so that the energy exceeding the critical value is continuously consumed by the newly added dummy load, and it works well. To the role of voltage and frequency stabilization. In addition, the present invention aims at the technical problem that the voltage change rate of the self-excited asynchronous generator is too high when the capacitor is connected in parallel. The series capacitor C _A is used to provide additional capacitive reactive power, so that the voltage change rate of the asynchronous motor can be improved. When no-load excitation When the capacitor and the series capacitor C _A are properly matched, the output voltage can be basically unchanged and play a role in stabilizing the voltage.

In summary, the present invention comprehensively considers the elimination of reverse power generation phenomenon, reactive power compensation and speed control, can completely eliminate the reverse power generation phenomenon of the pumping unit driving the asynchronous motor, and fully utilize the power generated by the asynchronous motor to measure the speed; It is an optimal energy-saving scheme that not only effectively solves the problem of speed out of control by using the frequency-stabilizing and voltage-stabilizing circuit, but also performs reactive power compensation in the electric state of the asynchronous motor.

The technical solutions of the present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

Description of drawings

Fig. 1 is the flow chart of beam pumping unit asynchronous motor energy-saving control method of the present invention;

Fig. 2 is the flowchart of judging the moment when the asynchronous motor enters the power generation state by the computer controller of the present invention;

Fig. 3 is the flowchart of judging the moment when the asynchronous motor enters the electric state by the computer controller of the present invention;

Fig. 4 is the flowchart of the preferred scheme of the energy-saving control method for the asynchronous motor of the beam pumping unit of the present invention;

Fig. 5 is a flow chart of the disconnection process of the first and second switch assemblies of the present invention;

6 is a flowchart of the closing process of the first and second switch assemblies of the present invention;

Fig. 7 is a structural schematic diagram of the energy-saving control device for the asynchronous motor of the beam pumping unit of the present invention;

Fig. 8 is a structural schematic diagram of a preferred solution of the present invention;

Fig. 9 is a circuit diagram of frequency stabilization and voltage stabilization of the present invention;

Figures 10 to 12 are schematic diagrams of the frequency and voltage stabilization circuit of the present invention;

Fig. 13 is a working principle diagram of the energy-saving control device for the asynchronous motor of the beam pumping unit of the present invention;

Fig. 14 is a circuit diagram of the energy-saving control device for the asynchronous motor of the beam pumping unit of the present invention.

Explanation of reference signs:

1-AC power switch; 2-AC power; 3-switch;

4-Original control system switch; 5-Asynchronous motor; 6-Switch;

7-Switch; 8-Pumping unit mechanical system; 9-Electronic pressure regulating switch;

10-current transformer; 11-no-load excitation capacitor; 12-voltage transformer;

13-current transformer; 14-mechanical switch; 15-current transformer;

16-data acquisition unit; 17-frequency stabilization circuit; 18-drive unit;

19-computer controller; 20-pseudo-load switch; 21-pseudo-load;

22-DC power switch; 23-DC power supply and protection circuit; 24-Electronic switch;

25-current transformer; 26-reactive power compensation capacitor; 27-mechanical switch;

28-current transformer; 29-excitation switch; 30-first switch assembly;

40 - Second switch assembly.

Detailed ways

Fig. 1 is the flow chart of the energy-saving control method for the asynchronous motor of the beam pumping unit of the present invention, comprising steps:

Step 10, in the power-on running state of the asynchronous motor, the data acquisition unit collects the voltage and current instantaneous values of the asynchronous motor in real time during operation, and transmits the voltage and current data to the computer controller;

Step 20, when the computer controller judges that the asynchronous motor enters the power generation state according to the voltage and current data, output a control signal to the drive unit;

Step 30, the drive unit controls the first switch assembly to cut off the connection between the asynchronous motor and the AC power supply;

Step 40, the asynchronous motor and the no-load excitation capacitor form an island power generation system, and the data acquisition unit collects the instantaneous voltage and current values of the asynchronous motor in the island power generation system in real time, and transmits the voltage and current data to the computer controller;

Step 50, the computer controller judges that the asynchronous motor enters the motoring state according to the voltage and current data of the asynchronous motor in the island power generation system, and outputs a control signal to the drive unit;

Step 60, the drive unit controls the first switch assembly to restore the connection between the asynchronous motor and the AC power supply, returns to step 10, and enters the next working cycle.

According to the actual operating conditions of the asynchronous motor of the existing beam pumping unit, the present invention divides the operation within one cycle into two stages: the electric state stage and the power generation state stage. In the motoring state stage of the asynchronous motor, the starting moment of the asynchronous motor power generation state is judged by collecting the instantaneous value of the voltage and current of the asynchronous motor; Capacitors form an island power generation system. By collecting the instantaneous values of the voltage and current of the asynchronous motor in the island power generation system, the starting moment of the asynchronous motor's electric state can be judged; Invented a working cycle that completely eliminates the phenomenon of "backward power generation". The outstanding features of the above technical solutions are reflected in the stage of power generation. On the one hand, the asynchronous motor is disconnected from the power grid; on the other hand, the asynchronous motor and the no-load excitation capacitor form an island power generation system. Voltage, so that the computer controller can obtain the voltage and current data of the asynchronous motor through the data acquisition unit, so as to calculate the speed of the asynchronous motor, so that the judgment of the moment when the asynchronous motor enters the electric state can be realized. The technical solution of the present invention is not only different from the simple power failure of the prior art, but also has essential differences from the prior art of clutching the shaft of the asynchronous motor and the sucker rod. The island power generation technology makes full use of the energy signal generated by the asynchronous motor for data collection, turning the unfavorable factors of "reverse power generation" into favorable energy, thus realizing the energy saving effect to the greatest extent.

Fig. 2 is the flow chart of judging the moment when the asynchronous motor enters the power generation state by the computer controller of the present invention, specifically:

Step 201, the computer controller calculates the active power value of the asynchronous motor according to the voltage and current data;

Step 202, when the active power value is less than the power preset value, the computer controller determines that the asynchronous motor starts to enter the power generation state;

Step 203, the computer controller outputs a control signal to the drive unit.

The invention adopts the active power calculation method of the asynchronous motor to realize the judgment of the moment when the asynchronous motor enters the power generation state, that is, the time when the reverse power generation occurs is judged by the zero-crossing point of the active power value.

Fig. 3 is the flow chart of judging the moment when the asynchronous motor enters the electric state by the computer controller of the present invention, specifically:

Step 501, the soft instrument unit of the computer controller calculates the speed of the asynchronous motor according to the voltage and current data of the asynchronous motor in the island power generation system;

Step 502, the computer controller calculates the difference between the rotational speed and the synchronous rotational speed of the asynchronous motor;

Step 503, when the difference is less than the preset difference, the computer controller determines that the asynchronous motor starts to enter the electric state;

Step 504, the computer controller outputs a control signal to the drive unit.

The invention adopts the online non-contact soft measurement method of the speed of the asynchronous motor to realize the judgment of the moment when the asynchronous motor enters the electric state, that is, the end time of the power generation state is judged when the speed is close to the synchronous speed of the asynchronous motor.

It can be seen from the above technical solution that the present invention only needs to collect the voltage and current data of the asynchronous motor to complete the judgment of the two status stages. The invention has the characteristics of simple structure, reliable system operation, high control precision, fast dynamic response and easy implementation.

In the above-mentioned technical solution of the present invention, the asynchronous motor is connected with a series-connected dummy load and a frequency stabilizing and voltage stabilizing circuit, so as to control the rotational speed of the asynchronous motor within a safety critical range, and the steps are as follows:

Step 31, the frequency stabilizing circuit automatically monitors the no-load voltage of the asynchronous motor;

Step 32. When the no-load voltage of the asynchronous motor is greater than the preset safety critical voltage, the thyristor of the frequency stabilizing circuit is turned on, and the dummy load consumes supercritical energy;

Step 33. When the no-load voltage of the asynchronous motor falls within the preset safety critical voltage range, the thyristor of the frequency stabilizing circuit is turned off.

The no-load voltage of the asynchronous motor is higher than the preset safety critical voltage, which means that the speed of the asynchronous motor exceeds the safety critical speed, and the energy stored in the asynchronous motor needs to be automatically released through the frequency stabilization circuit to reduce its speed to the preset safety critical speed within the speed range. The above-mentioned technical solution of the present invention effectively solves the problem of out-of-control rotation speed of the asynchronous motor, and improves the implementability and reliability of the present invention.

In the above technical solution of the present invention, when the asynchronous motor enters the electric state, a reactive power compensation capacitor can be connected in parallel to the AC power circuit to realize reactive power compensation for the asynchronous motor in the electric state, further improving the energy saving effect of the present invention . Specifically, after step 60, set the drive unit to control the second switch assembly to close, and connect the reactive power compensation capacitor in parallel to the step 61 of the AC power supply. Correspondingly, set the drive unit to control the first Step 21 of disconnecting the switch assembly and cutting off the connection between the reactive power compensation capacitor and the AC power supply. This solution realizes that when the asynchronous motor is in the electric state, the power factor of the asynchronous motor can be improved by putting in a reactive power compensation capacitor, so that the present invention has obvious energy-saving effect under various working conditions. When the asynchronous motor is in the power generation state, the reactive power compensation capacitor is removed, which eliminates the technical defect that the reactive power compensation capacitor in the prior art enhances the power generation effect of the asynchronous motor and brings new waste of electric energy.

Fig. 4 is the flowchart of the preferred scheme of the energy-saving control method for the asynchronous motor of the beam pumping unit of the present invention, specifically:

Step 10, in the power-on running state of the asynchronous motor, the data acquisition unit collects the voltage and current instantaneous values of the asynchronous motor in real time during operation, and transmits the voltage and current data to the computer controller;

Step 20, when the computer controller judges that the asynchronous motor enters the power generation state according to the voltage and current data, output a control signal to the drive unit;

Step 21, the drive unit controls the second switch assembly to be disconnected, and cuts off the connection between the reactive power compensation capacitor and the AC power supply;

Step 30, the drive unit controls the first switch assembly to cut off the connection between the asynchronous motor and the AC power supply;

Step 31, the frequency stabilizing circuit automatically monitors the no-load voltage of the asynchronous motor;

Step 32. When the no-load voltage of the asynchronous motor is greater than the preset safety critical voltage, the thyristor of the frequency stabilizing circuit is turned on, and the dummy load consumes supercritical energy;

Step 33, when the no-load voltage of the asynchronous motor is reduced to within the preset safety critical voltage range, the thyristor of the frequency stabilizing circuit is turned off;

Step 40, the data acquisition unit collects the instantaneous voltage and current values of the asynchronous motor in the island power generation system in real time, and transmits the voltage and current data to the computer controller;

Step 50, the computer controller judges that the asynchronous motor enters the motoring state according to the voltage and current data of the asynchronous motor in the island power generation system, and outputs a control signal to the drive unit;

Step 60, the drive unit controls the first switch assembly to restore the connection between the asynchronous motor and the AC power supply;

Step 61 , the drive unit controls the second switch assembly to connect the reactive power compensation capacitors in parallel to the AC power supply, return to step 10, and enter the next working cycle.

In the above technical solution, the first switch assembly is composed of electronic voltage regulating switches and mechanical switches connected in parallel, and the second switch assembly is composed of electronic switches and mechanical switches connected in parallel. The purpose of operational reliability and further energy saving.

Fig. 5 is the flowchart of the disconnection process of the first and second switch assemblies of the present invention, specifically:

Step 110, the drive unit controls the electronic switch to close;

Step 120, the computer controller detects whether the electronic switch is closed through the data acquisition unit, and executes step 130 when the closure is successful, otherwise a fault alarm is issued;

Step 130, the drive unit controls the mechanical switch to be turned off;

Step 140, the computer controller detects whether the mechanical switch has been disconnected through the data acquisition unit, and executes step 150 when the disconnection is successful, otherwise a fault alarm is issued;

Step 150, the drive unit controls the electronic switch to be turned off;

Step 160, the computer controller detects whether the electronic switch has been disconnected through the data acquisition unit, and executes step 170 when the disconnection is successful, otherwise a fault alarm is issued;

Step 170, the disconnection is completed.

Fig. 6 is a flowchart of the closing process of the first and second switch assemblies of the present invention, specifically:

Step 210, the drive unit controls the electronic switch to close;

Step 220, the computer controller detects whether the electronic switch is closed through the data acquisition unit, and executes step 230 when the closure is successful, otherwise a fault alarm is issued;

Step 230, the drive unit controls the mechanical switch to close;

Step 240, the computer controller detects whether the mechanical switch has been closed through the data acquisition unit, and executes step 250 when the closure is successful, otherwise a fault alarm is issued;

Step 250, the drive unit controls the electronic switch to be turned off;

Step 260, the computer controller detects whether the electronic switch has been disconnected through the data acquisition unit, and executes step 270 when the disconnection is successful, otherwise a fault alarm is issued;

Step 270, closing is completed.

In step 210 of the closing process of the first switch assembly, the drive unit controls the electronic voltage regulating switch to complete the voltage regulating process, and the rest of the steps are the same as the process shown in FIG. 6 .

It can be seen from the technical solutions in Fig. 5 and Fig. 6 of the present invention that the electronic switch is responsible for the cutting off when the current crosses zero and the non-transient input of the voltage zero crossing, while the electronic voltage regulating switch is responsible for the cutting off when the current crosses zero and the voltage changes from zero to zero. Gradually boost the voltage to the rated value to prevent the impact of overload current when putting it on, and connect the mechanical switch when the asynchronous motor or capacitor is running normally. This scheme can not only eliminate the new heat energy consumption caused by the operation of the electronic switch alone, but also solve the problem of the limited life of the mechanical switch alone due to frequent actions, and has an energy-saving effect at the same time. The fault alarm in the above technical solution can also be set to exit the operation of the present invention, or the present invention exits the operation after the alarm, but no matter what action is set, the original system can operate normally.

Parameters such as the asynchronous motor synchronous speed, safety critical speed, and preset safety critical voltage involved in the above technical solution of the present invention are pre-set in the computer controller. Considering the different working states of the asynchronous motors in different environments and different working conditions, the present invention can make the setting of the above parameters more accurate through the learning process. In the learning process of the present invention put into operation for the first time, after the computer controller collects the working cycle data of the pumping unit, the parameter value in one working cycle of the asynchronous motor of the pumping unit is determined. At the same time, the present invention can also be set to automatically learn at regular intervals during the normal operation of the system, and constantly update the parameters required by the computer controller, so that the present invention has higher control precision and more significant energy-saving effects.

Fig. 7 is a schematic structural diagram of the energy-saving control device for the asynchronous motor of the beam pumping unit of the present invention, in which thick lines represent strong current circuits and thin lines represent weak current circuits. As shown in FIG. 7 , the energy-saving control device for the asynchronous motor of the beam pumping unit of the present invention includes a computer controller 19 , a drive unit 18 , a data acquisition unit 16 , an unloaded excitation capacitor 11 and a first switch assembly 30 . Among them, the first switch assembly 30 is connected in series in the circuit of the AC power supply 2 and the asynchronous motor 5, and is responsible for connecting and disconnecting the asynchronous motor 5 and the AC power supply 2; the no-load excitation capacitor 11 is connected with the asynchronous motor 5, when the asynchronous motor 5. When disconnected from the AC power supply 2 and operated as a generator, the no-load excitation capacitor 11 acts as an excitation to generate no-load voltage; the drive unit 18 is connected to the computer controller 19 and the first switch assembly 30 respectively, and receives the computer controller 19 The control signal sent out controls the first switch assembly 30 to turn on and off; the data acquisition unit 16 is responsible for collecting the instantaneous voltage and current values of the asynchronous motor 5 and sending the data to the computer controller 19 . The working process of the beam pumping unit asynchronous motor energy-saving control device of the present invention is: the asynchronous motor 5 runs under the electric state, and the data acquisition unit 16 collects the voltage and current instantaneous value of the asynchronous motor 5 in real time when it is running, and transmits the data to Computer controller 19; when computer controller 19 judges that asynchronous motor 5 enters power generation state, output control signal to drive unit 18; Drive unit 18 controls first switch assembly 30 to disconnect, and cuts off the connection of asynchronous motor 5 and AC power supply 2; asynchronous The motor 5 and the no-load excitation capacitor 11 form an island power generation system, and the no-load excitation capacitor 11 plays an excitation role to generate no-load voltage; the data acquisition unit 16 collects the voltage and current instantaneous value of the asynchronous motor 5 in the island power generation system in real time, and The data is transmitted to the computer controller 19; when the computer controller 19 judges that the asynchronous motor 5 enters the electric state, it outputs a control signal to the drive unit 18; the drive unit 18 controls the first switch assembly 30 to close, and restores the connection between the asynchronous motor 5 and the AC power supply 2 , the asynchronous motor 5 re-runs in the electric state; such a cycle is a complete working cycle of the present invention.

The core of the above-mentioned technical solution is embodied in the power generation state stage of the asynchronous motor 5. Although the asynchronous motor 5 has been disconnected from the AC power supply 2 at this time and is in a power-off state, the present invention is provided with a no-load excitation capacitor 11 connected to the asynchronous motor 5 , so that the asynchronous motor 5 and the no-load excitation capacitor 11 form an island power generation system, the no-load excitation capacitor 11 plays an excitation role to generate no-load voltage, so that the no-load voltage frequency of the asynchronous motor 5 can be measured, and the computer controller 19 passes The data acquisition unit 16 obtains the operating parameters of the asynchronous motor 5, so it can realize the judgment of the moment when the asynchronous motor 5 enters the electric state. The no-load exciting capacitor 11 of the present invention can be a delta-connected exciting capacitor, or a star-connected exciting capacitor. It can be seen that the above-mentioned technical solution of the present invention has not only realized the power failure in the power generation state of the asynchronous motor 5, so that the electric energy generated by the asynchronous motor 5 will not interfere with and pollute the power grid, but also form a The rationally designed island power generation system makes full use of the electric energy generated by the asynchronous motor 5 for data collection, turns the unfavorable factor of "inverting power generation" into favorable energy, and also has the function of electric energy storage, thus realizing energy saving to the greatest extent.

The computer controller 19 of the present invention includes a serially connected control unit 191 and a soft instrument unit 192, wherein the soft instrument unit 192 is connected with the data acquisition unit 16 for calculating the rotational speed and active power of the asynchronous motor 5 according to the received voltage and current data Value, the control unit 191 is connected with the drive unit 18, and is used to judge the moment when the asynchronous motor 5 enters the power generation state or the electric state according to the calculation result output by the soft instrument unit 192, and sends an off or on control signal to the drive unit 18. Specifically, when the asynchronous motor 5 is in the motoring state, the soft instrument unit 192 calculates its active power value, and the control unit 191 judges the time when the reverse generation occurs through the zero-crossing point of the active power value. When the asynchronous motor 5 is in the power generation state, the soft instrument unit 192 calculates its rotational speed, and the control unit 191 judges the end time of reverse power generation by the rotational speed close to the synchronous rotational speed of the asynchronous motor. Because the present invention introduces island power generation technology, a data acquisition unit 16 can complete the voltage and current data acquisition of the asynchronous motor 5 in two state stages, and realize the judgment of the asynchronous motor 5 electric and power generation states by setting the soft instrument unit 192, which is relatively The prior art adopts a mechanical rotational speed measuring device, and the present invention has the characteristics of high control precision, fast dynamic response, simple structure, reliable system operation and easy realization.

Fig. 8 is a schematic structural diagram of a preferred solution of the present invention, in which thick lines represent strong current circuits, and thin lines represent weak current circuits. In the preferred technical solution shown in FIG. 8 , the asynchronous motor 5 is connected with a dummy load 21 and a frequency stabilizing and voltage stabilizing circuit 17 connected in series. On the basis of the technical scheme in Figure 7, the working process of the frequency stabilization and voltage stabilization circuit 17 is as follows: when the asynchronous motor 5 enters the power generation state, the asynchronous motor 5 and the no-load excitation capacitor 11 form an island power generation system, and the no-load excitation capacitor 11 acts as an excitation function to generate no-load voltage, the frequency stabilizing and voltage stabilizing circuit 17 automatically monitors the no-load voltage of the asynchronous motor, when the no-load voltage of the asynchronous motor is higher than the preset safety critical voltage, the thyristor of the frequency stabilizing and voltage stabilizing circuit 17 is turned on , the pseudo load consumes supercritical energy until the no-load voltage of the asynchronous motor is reduced to within the preset safety critical voltage range.

In the above preferred technical solution, the no-load voltage of the asynchronous motor is higher than the preset safety critical voltage means that the speed of the asynchronous motor 5 exceeds the safety critical speed, and the energy stored in the asynchronous motor needs to be automatically released through the frequency stabilizing and voltage stabilizing circuit 17. Its speed is reduced to within the preset safety critical speed range. Therefore, the present invention effectively solves the problem of out-of-control rotation speed of the asynchronous motor 5 by connecting the frequency stabilizing and voltage stabilizing circuit 17 and the dummy load 21, and improves the implementability and reliability of the present invention. In addition, the dummy load 21 is composed of capacitors and resistors in series. Aiming at the technical problem that the voltage change rate of the self-excited asynchronous generator is too high when the capacitors are connected in parallel, the present invention uses series capacitors to provide additional capacitive reactive power, so that the voltage of the asynchronous motor The rate of change is improved.

In the preferred technical solution shown in Figure 8, the AC power supply 2 can also be connected in parallel with a reactive power compensation capacitor 26 through a second switch assembly 40 to realize reactive power compensation to the asynchronous motor 5 in the motoring state, further improving the performance of the present invention. energy-saving effect. Specifically, the second switch component 40 is connected in series with the reactive power compensation capacitor 26 , and the second switch component 40 is connected with the drive unit 18 for switching on or off the reactive power compensation capacitor 26 . On the basis of the technical scheme in Fig. 7, the working process of switching on and off the reactive power compensation capacitor 26 is as follows: when the asynchronous motor 5 enters the electric state, the computer controller 19 outputs a control signal to the drive unit 18, and the drive unit 18 first controls the first The switch component 30 is closed, the asynchronous motor 5 is connected to the AC power source 2 , and then the second switch component 40 is controlled to close, and the reactive power compensation capacitor 26 is input. When the asynchronous motor 5 enters the power generation state, the drive unit 18 controls the second switch assembly 40 to be turned off, first removes the reactive compensation capacitor 26 , and then turns off the first switch assembly 30 . The present invention improves the power factor of the asynchronous motor 5 by setting the reactive power compensation capacitor 26, so that the asynchronous motor 5 also has excellent energy-saving performance in the electric state. When the asynchronous motor is in the power generation state, the reactive power compensation capacitor is automatically removed, which eliminates the technical defect that the reactive power compensation capacitor in the prior art enhances the power generation effect of the asynchronous motor and brings new waste of electric energy.

In the above technical solution of the present invention, the first switch assembly 30 is an electronic voltage regulating switch and a mechanical switch connected in parallel, and the second switch assembly 40 is an electronic switch and a mechanical switch connected in parallel, which are respectively connected to the drive unit 18 . Among them, the electronic voltage regulating switch is responsible for cutting off the current of the asynchronous motor 5 when it crosses zero and gradually boosting the voltage from zero to the rated value to prevent the impact of overload current when it is put into operation, and the electronic switch has other functions except the voltage regulating function. The electronic tap switch function is the same. Its working procedure is to close the electronic switch or electronic voltage regulating switch first, then close or disconnect the mechanical switch, and finally disconnect the electronic switch or electronic voltage regulating switch after the action of the mechanical switch is completed. The computer controller 19 detects the action results of the electronic switch and the mechanical switch through the data acquisition unit 16, and performs the next action after the previous action is completed correctly, which ensures the reliability of the system control. The electronic switch of the present invention is preferably a controllable device such as a thyristor or IGBT, and the mechanical switch is preferably an AC contactor. This solution can not only eliminate the new heat energy consumption caused by the operation of the electronic switch alone, but also solve the problem of the limited life of the mechanical switch alone due to frequent actions with load, and has an energy-saving effect at the same time.

Fig. 9 is a circuit diagram of frequency stabilization and voltage stabilization in the present invention. Only phase A is drawn in Fig. 9, and the circuits of phase B and phase C are exactly the same as phase A, and they are adjusted in N gears. As shown in Figure 9, T _A is a bidirectional thyristor, G ₁ is the control pole of _TA , C _A and R _A are the capacitance and resistance of phase A, D ₁ ... D _N are trigger tubes, C ₁₁ , C ₂₁ ...C _1N and C _2N are capacitors, R ₁ ...R _N are resistors, W ₁ ...W _N are potentiometers, and N is a neutral wire. U _a is the A-phase voltage of the asynchronous motor, U ₁ ... U _N is the voltage value of the A-phase voltage applied to the trigger tube D ₁ ... D _N after phase shifting and voltage division, U _d1 ... U _dN is the trigger The breakdown voltage values of tubes D ₁ ... D _N , U _m1 ... U _mN are the amplitudes of U ₁ ... U _N respectively, and α ₁ ... α _N are the voltages of U ₁ ... U _N lagging behind U _a Phase angle, the circuit design has a relationship of α ₁ <...<α _N , so U _m1 >...>U _mN holds true. The dotted frame in FIG. 9 corresponds to the dummy load 21 in FIG. 8, which is composed of a resistor _RA and a capacitor _CA.

When the speed of the asynchronous motor 5 increases, the voltage U _a increases accordingly, and U _m1 ... U _mN also increases accordingly. When U _m1 = U _d1 , the trigger tube D ₁ sends a pulse at (90-α ₁ ), the bidirectional thyristor T _A is triggered to conduct at (90-α ₁ ), and the current flows through the resistor R _A of phase A , consumes supercritical energy, as shown in Figure 10. If the rotation speed continues to increase, the voltage U _a will further increase, so that U _mi = U _di , the trigger tube D _i will send out a pulse at (90-α _i ), and the bidirectional thyristor _TA will be at (90-α _i ) is triggered to conduct, as shown in Figure 11. ……If the rotating speed continues to rise, the voltage U _a rises, so that U _mN = U _dN , the trigger tube _DN sends a pulse at (90-α _N ), and the bidirectional thyristor _TA is activated at (90-α _N ) Trigger conduction, as shown in Figure 12. That is to say, when the speed of the asynchronous motor starts to increase from the safety critical speed, the trigger pulse on the triac T _A can start from scratch, and move forward from (90-α ₁ ) to (90-α _N ) , the load controlled by the bidirectional thyristor _TA changes from scratch, from small to large, so that the energy exceeding the critical value is consumed by the newly added pseudo load, which plays a role in frequency stabilization.

The prominent problem of parallel capacitor self-excited asynchronous generators is that the voltage change rate is too high. When the speed increases, the voltage at the asynchronous motor terminal increases, which is equivalent to the increase in load. In order to keep the voltage unchanged, the method of increasing the capacitance is adopted. The practice is very inconvenient. The present invention uses the series capacitor C _A to provide additional capacitive reactive power, so that the voltage change rate of the asynchronous motor can be improved. When the no-load excitation capacitor 11 and the series capacitor C _A are properly matched, the output voltage can be kept basically unchanged, which plays a role The role of voltage regulation.

Fig. 13 is a schematic diagram of the working principle of the energy-saving control device for the asynchronous motor of the beam pumping unit of the present invention. In the figure, thick lines represent strong current circuits, and thin lines represent weak current circuits. Fig. 14 is a circuit diagram of the energy-saving control device for the asynchronous motor of the beam pumping unit of the present invention, in which only the strong current part is highlighted in Fig. 14 . The technical solution of the present invention will be further described in detail through the installation, debugging and operation process of the present invention.

A. System installation:

1. If the asynchronous motor in the original system of pumping unit 8 has no reactive power compensation, disconnect the AC power switch 1, connect the present invention to the original system, and complete the connection of switch 3, switch 6 and switch 7 shown in Figure 14 can;

2. If the asynchronous motor in the original system of the pumping unit has reactive power compensation, it will be canceled;

3. Turn the AC power switch 1 back on and the original system will work normally.

B. Put into operation:

1. State before power on

The switch 6 is disconnected, the switch 7 is disconnected, the switch 3, the AC power switch 1 and the original control system switch 4 are closed, the original control system of the pumping unit works as usual, and the present invention is ready to be put into operation.

2. The present invention is electrified

Manually close the switch 6, close the DC power switch 22 after the power system is normal, the DC power supply and the protection circuit 23 are put into operation, the computer controller 19 starts to work, and enters the self-checking state. If the self-test fails, it will exit the operation.

3. Test of the present invention

After the computer controller 19 self-test is correct, the computer controller 19 is set to the on-load test operation mode. The computer controller 19 automatically carries out the following operations: the closed excitation switch 29, the no-load excitation capacitor 11 is put into operation; the closed dummy load switch 20, the frequency and voltage stabilization circuit 17 and the dummy load 21 are put into operation; the present invention enters the on-load test state, and the test The content mainly includes the control of the electronic voltage regulating switch 9 and the mechanical switch 14 and the correctness of the measurement signals of the current transformers 10, 13 and 15. After the test is successful, make the electronic voltage regulating switch 9 and the mechanical switch 14 in the off position, make the excitation switch 29 and the dummy load switch 20 in the closed state, and turn to the next step. Exit if there is a fault.

4. The present invention is put into operation

The computer controller 19 is set to the automatic operation mode, the computer controller 19 sequentially controls the switch 7 and the switch 9 to close, and the switch 3 is turned off, and the present invention is put into operation and coordinates with the original control system of the pumping unit. After the commissioning fails, the switch 6 and the switch 7 are disconnected, the switch 3 is closed, and the present invention quits operation.

C. Learning stage:

The data acquisition unit 16 collects the instantaneous data of the asynchronous motor 5 operating voltage and current in real time; the computer controller 19 starts automatic learning according to the working cycle data of the collected pumping unit, and determines the key points in a working cycle of the pumping unit asynchronous motor. Parameter value: the time and starting point of the asynchronous motor in the electric state, the time and starting point of the asynchronous motor in the generating state. Real-time detection of pumping unit status, ready to enter the stage of asynchronous motor power generation.

D. Asynchronous motor power generation state stage:

When the computer controller 19 judges that the asynchronous motor 5 enters the power generation state, the work steps are:

1. Cut off the reactive power compensation capacitor 26

(1) The computer controller 19 closes the electronic switch 24 by the drive unit 18, and the data acquisition unit 16 feeds back the current signal of the current transformer 25 to the computer controller 19. When it is detected that there is an electric current, it shows that the closing is successful, otherwise it shows that the electronic Switch 24 failure;

(II) The computer controller 19 disconnects the mechanical switch 27 by the drive unit 18, and the data acquisition unit 16 feeds back the current signal of the current transformer 28 to the computer controller 19. When no current is detected, it is explained that the disconnection is successful, otherwise it is explained. Mechanical switch 27 failure;

(III) The computer controller 19 disconnects the electronic switch 24 by the drive unit 18, and the data acquisition unit 16 feeds back the current signal of the current transformer 25 to the computer controller 19. When it is detected that there is no current, it is explained that the disconnection is successful, otherwise it is explained. Electronic switch 24 is faulty.

The above is only the process of removing one set of reactive power compensation capacitors, and repeat the above steps when there are multiple sets.

2. Remove the asynchronous motor 5

(1) the computer controller 19 closes the electronic voltage regulating switch 9 by the drive unit 18, and the data acquisition unit 16 feeds back the current signal of the current transformer 10 to the computer controller 19, and when it is detected that there is an electric current, it is explained that the closing is successful, Otherwise, it means that the electronic voltage regulating switch 9 is faulty;

(II) The computer controller 19 disconnects the mechanical switch 14 by the drive unit 18, and the data acquisition unit 16 feeds back the current signal of the current transformer 15 to the computer controller 19. When no current is detected, it is explained that the disconnection is successful, otherwise it is explained. Mechanical switch 14 failure;

(III) The computer controller 19 disconnects the electronic voltage regulating switch 9 through the drive unit 18, and the data acquisition unit 16 feeds back the current signal of the current transformer 10 to the computer controller 19, and when it is detected that there is no current, the switch 9 is disconnected If successful, otherwise, the electronic pressure regulating switch 9 is faulty.

3. The computer controller 19 judges the moment when the asynchronous motor 5 enters the electric state

After the asynchronous motor 5 withdraws from the power grid, the asynchronous motor 5 enters the no-load power generation state, and changes part of its potential energy into rotational kinetic energy. The no-load excitation capacitor 11 provides no-load excitation, and the pumping unit mechanical system 8, asynchronous motor 5, The original control system switch 4, switch 7, excitation switch 29 and no-load excitation capacitor bank 11 form an island power generation system, while the current transformer 13, voltage transformer 12, data acquisition unit 16 and computer controller 19 form a data acquisition system. Collect the instantaneous voltage and current values of the asynchronous motor 5, and calculate online the parameters that the asynchronous motor 5 satisfies the energization conditions according to the cycle or frequency of the voltage and current, that is, the time and starting point when the asynchronous motor 5 is in the electric state.

4. Asynchronous motor 5 safety critical speed and safety critical voltage control

After the no-load voltage of the asynchronous motor 5 is established, the frequency stabilizing and voltage stabilizing circuit 17 automatically monitors the no-load voltage of the asynchronous motor 5, and when it is higher than the safety critical voltage, the thyristor of the frequency stabilizing and voltage stabilizing circuit 17 is turned on, and the false load 21 Consume supercritical energy, release the energy stored in the asynchronous motor 5, reduce the voltage of the asynchronous motor 5 to within the safety critical voltage range, that is, reduce the speed of the asynchronous motor 5 to within the safe critical speed range. When the no-load voltage of the asynchronous motor falls within the preset safety critical voltage range, the thyristor of the frequency stabilizing and voltage stabilizing circuit is turned off.

5. When the computer controller 19 judges that the asynchronous motor 5 enters the electric state, the present invention will turn over to the electric state of the asynchronous motor to run, and the present invention will exit the operation when there is a fault.

E. The electric state stage of the asynchronous motor:

When the computer controller 19 judged that the asynchronous motor 5 entered the electric state, the working steps of the present invention were:

1. Put in the asynchronous motor 5

(1) Computer controller 19 closes electronic voltage regulating switch 9 by drive unit 18, and electronic voltage regulating switch 9 increases voltage step by step until rated value by changing the firing angle, and the current signal of current transformer 10 is fed back to computer through data acquisition unit 16 When the controller 19 detects that there is a current, it indicates that the closing is successful, otherwise it indicates that the electronic voltage regulating switch 9 is faulty;

(II) The computer controller 19 closes the mechanical switch 14 through the drive unit 18, and the current signal of the current transformer 15 is fed back to the computer controller 19 through the data acquisition unit 16. When it is detected that there is an electric current, it shows that the closing is successful, otherwise it shows that the mechanical switch 14 failure;

(III) Computer controller 19 disconnects electronic voltage regulating switch 9 by drive unit 18, and the current signal of current transformer 10 is fed back to computer controller 19 through data acquisition unit 16, and when detecting that there is no electric current, it is explained that switch is disconnected successfully, Otherwise, it indicates that the electronic voltage regulating switch 9 is faulty.

2. Put in reactive power compensation capacitor 26

(1) Computer controller 19 closes electronic switch 24 by drive unit 18, and the current signal of current transformer 25 is fed back to computer controller 19 through data acquisition unit 16, and when detecting that there is electric current, explain closing success, otherwise electronic switch is explained 24 failure;

(II) The computer controller 19 closes the mechanical switch 27 through the drive unit 18, and the current signal of the current transformer 28 is fed back to the computer controller 19 through the data acquisition unit 16. When it is detected that there is an electric current, it shows that the closing is successful, otherwise it shows that the mechanical switch 27 failure;

(III) The computer controller 19 disconnects the electronic switch 24 through the drive unit 18, and the current signal of the current transformer 25 is fed back to the computer controller 19 through the data acquisition unit 16. Switch 24 failed.

The above is only the process of putting in one set of reactive power compensation capacitors, and repeat the above steps when there are multiple sets.

3. The computer controller 19 judges the moment when the asynchronous motor 5 enters the electric state

The asynchronous motor 5 enters the electric operation stage, the data acquisition unit 16 collects the voltage and current instantaneous value of the asynchronous motor 5 in real time, and the computer controller 19 calculates the parameters that the asynchronous motor 5 satisfies the power-off condition online, that is, the time when the asynchronous motor 5 is in the power generation state and starting point. When the computer controller 19 judges that the asynchronous motor 5 enters the power generation state, the present invention will transfer to the asynchronous motor power generation state stage operation, and the present invention exits the operation when there is a fault.

F, the present invention exits operation

Disconnect switch 6 and switch 7, close switch 3, the present invention withdraws from operation, and the original control system of pumping unit works alone.

In the operation of the present invention, the switch failure can be set as a fault alarm, or it can be set to exit the operation of the present invention, or the present invention will exit the operation after the alarm, but no matter what action is set, the original system can operate normally.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention without limitation. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be The scheme shall be modified or equivalently replaced without departing from the spirit and scope of the technical scheme of the present invention.

Claims (10)

1. asynchronous motor of walking-beam pumping unit energy-saving control method wherein, comprises step:

Step 10, under asynchronous machine energising running status, the voltage and current instantaneous value when data acquisition unit is gathered the asynchronous machine operation in real time, and give computer control with the voltage and current transfer of data;

When step 20, computer control judged that according to described voltage and current data asynchronous machine enters generating state, the output control signal was given driver element;

Step 30, driver element are controlled first switch module and are cut off being connected of asynchronous machine and AC power;

Step 40, asynchronous machine and open-circuit excitation capacitor form the isolated island electricity generation system, and data acquisition unit is gathered the voltage and current instantaneous value of asynchronous machine in the described isolated island electricity generation system in real time, and give computer control with the voltage and current transfer of data;

When step 50, computer control judged that according to the voltage and current data of asynchronous machine in the described isolated island electricity generation system asynchronous machine enters motoring condition, the output control signal was given driver element;

Step 60, driver element are controlled first switch module and are recovered being connected of asynchronous machine and AC power.

2. asynchronous motor of walking-beam pumping unit energy-saving control method according to claim 1, wherein, described step 20 is specially:

Step 201, computer control are according to described voltage and current data computation asynchronous machine active power value;

Step 202, when described active power value during less than the power preset value, computer control judges that asynchronous machine begins to enter generating state;

Step 203, computer control output control signal are given driver element.

3. asynchronous motor of walking-beam pumping unit energy-saving control method according to claim 1, wherein, described step 50 is specially:

The soft instrument unit of step 501, computer control is according to the rotating speed of the voltage and current data computation asynchronous machine of asynchronous machine in the described isolated island electricity generation system;

Step 502, computer control calculate the difference of described rotating speed and asynchronous machine synchronous speed;

Step 503, when described difference during less than preset difference value, computer control judges that asynchronous machine begins to enter motoring condition;

Step 504, computer control output control signal are given driver element.

4. asynchronous motor of walking-beam pumping unit energy-saving control method according to claim 1 wherein, also comprises the step of a pseudo-load of connecting with asynchronous machine and frequency-and voltage-stabilizing circuit control asynchronous machine rotating speed before described step 30 back, the step 40, be specially:

Step 31, frequency-and voltage-stabilizing circuit are monitored the floating voltage of asynchronous machine automatically;

Step 32, when the floating voltage of asynchronous machine during, the controllable silicon conducting of frequency-and voltage-stabilizing circuit, the overcritical energy of pseudo-load consumption greater than default safety critical voltage;

Step 33, in the floating voltage of asynchronous machine is reduced to default safety critical voltage range the time, the controllable silicon of frequency-and voltage-stabilizing circuit turn-offs.

5. asynchronous motor of walking-beam pumping unit energy-saving control method according to claim 1, wherein, also comprise driver element control second switch assembly closure after the described step 60, with the reactive-load compensation capacitor step that inserts described AC power in parallel, correspondingly, comprise also before step 20 back in next one circulation, the step 30 that driver element control second switch assembly disconnects, cuts off reactive-load compensation capacitor and AC power step of connecting.

6. asynchronous motor of walking-beam pumping unit energy-saving control device, it is characterized in that, comprise first switch module and the open-circuit excitation capacitor that is connected with asynchronous machine that are connected on asynchronous machine and the ac power supply circuit, described first switch module is connected with its driver element that is switched on or switched off of control, described driver element and one sends the computer control that is switched on or switched off control signal and is connected, described computer control is connected with a data acquisition unit of gathering described asynchronous machine voltage and current instantaneous value, described computer control comprises the control unit and the soft instrument unit of serial connection, described soft instrument unit is connected with described data acquisition unit, be used for rotating speed and active power value according to the voltage and current data computation asynchronous machine that receives, described control unit is connected with described driver element, be used for judging that according to described active power or tachometer value asynchronous machine enters the moment of generating or motoring condition, and send disconnection or connect control signal to driver element.

7. asynchronous motor of walking-beam pumping unit energy-saving control device according to claim 6, it is characterized in that, described asynchronous machine also is connected with the frequency-and voltage-stabilizing circuit with the pseudo-load of a series connection, described frequency-and voltage-stabilizing circuit is the bidirectional triode thyristor circuit that many retainings are regulated, and described pseudo-load is the resistance and the electric capacity of serial connection.

8. asynchronous motor of walking-beam pumping unit energy-saving control device according to claim 6 is characterized in that, described AC power is the second switch assembly and the reactive-load compensation capacitor of a serial connection in parallel also, and described second switch assembly is connected with described driver element.

9. asynchronous motor of walking-beam pumping unit energy-saving control device according to claim 6 is characterized in that, described first switch module is electronic pressure regulating switch and a mechanical switch in parallel, and described electronic pressure regulating switch is connected with described driver element with mechanical switch.

10. asynchronous motor of walking-beam pumping unit energy-saving control device according to claim 8 is characterized in that, described second switch assembly is electronic switch and a mechanical switch in parallel, and described electronic switch is connected with described driver element with mechanical switch.

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