CN1327608C - Discontinuous power supply full-automatic controlling method and apparatus for motor of beam-pumping unit - Google Patents

Abstract

A fully automatic control method and device for controlling the intermittent power supply and continuous operation of the electric motor of the beam pumping unit. During continuous power supply, the data acquisition unit detects the voltage and current of the motor, and the main controller determines the number of power failures in a working cycle and the electrical parameters at the time of power failure. In the state of intermittent power supply, monitor whether the operating parameters of the motor have changed significantly, and determine whether to return to the state of continuous power supply or power-off protection; And the number of power outages keeps it in the normal range. By turning on the power and controlling the conduction angle of the thyristor when the motor speed is close to the synchronous speed, the current surge is prevented when the power is turned on. The data acquisition unit, the main controller, the drive unit and the power switching element provided by the invention can effectively complete the above automatic control process, and realize the automatic control of the continuous operation of the motor of the pumping unit with intermittent power supply.

Description

Automatic control method and device for intermittent power supply of electric motor of beam pumping unit

technical field

The invention relates to the field of petroleum exploitation machinery, in particular to an automatic control method and device for a motor of a beam pumping unit.

Background technique

In a working cycle of the beam pumping unit motor in the existing oil exploration field, there are usually two working conditions of the motor and the generator: in the generator working condition, there are still four kinds of electrical losses in the motor: stator copper loss , rotor copper loss, iron loss, additional loss. Among them, the iron loss and the no-load additional loss related to the iron loss are usually larger than the corresponding loss of the motor operating condition. The electric energy generated in the working condition of the generator produces losses in the primary and secondary windings of the transformer and the feeder line, and the remaining part appears as pulsating power output to the power system. This pulsating power belongs to the interference and pollution to the power grid, rather than the useful power provided to the power system.

Based on the above situation, the inventor provides a kind of automatic control method and device for continuous operation of a beam pumping unit with intermittent power supply. Its operation mode is to cut off the power when the motor is in the generator state. The gravitational potential energy and inertia continue to run, and when the motor reaches a certain speed, the power is turned on to complete the oil pumping task. After the power is cut off, the above four losses in the motor and the losses on the transformer winding and the feeder line are all or basically gone, so the electric energy can be significantly saved.

Although the operation mode of pumping unit interval pumping has long been known in oil production, that is, when the downhole liquid is less, it will stop, and the "interval pumping" mode of restarting the motor after the liquid gradually increases, but this operation mode is different from that of this patent. The intermittent power supply mode of operation is completely different. In the "intermittent pumping" operation mode, once the power is cut off, it will shut down, while the intermittent power supply mode of this patent is an operation mode that does not stop when the power is cut off.

Since a working cycle of the pumping unit is very short, the motor will be powered on and off frequently when the power supply is intermittent. If no effective measures are taken, the current of the asynchronous motor can usually reach about 7 times the rated current when it is powered on. Therefore, in order to realize the intermittent power supply operation of the motor of the pumping unit, a key problem that needs to be solved is when the power is turned on again after power off. How to prevent electric shock.

In addition, for a specific pumping unit, the effective weight of the pump shaft may be greater than or less than the equivalent weight of the eccentric counterweight, or the two are basically equal, so there are three different situations. Different situations require different control methods. For the same situation, the actual load is not fixed during operation, it will change with the amount of downhole liquid, liquid temperature, water content and other parameters. Therefore, when the intermittent power supply mode is adopted, it is necessary to carry out real-time identification of the operating parameters of the pumping unit, and timely adjust the power-off control parameters such as the power-off time according to the identification results; at the same time, the following problems should be effectively solved: power-off operation Prevent the speed from being too high or too low.

Contents of the invention

In order to change the operating status of the existing beam pumping unit motor, the present invention provides a full-automatic control method and device for continuous operation of the beam pumping unit motor with intermittent power supply, and implements intermittent power supply for the beam pumping unit Fully automatic control of operating modes.

For this reason, the beam pumping unit motor intermittent power supply continuous operation automatic control method provided by the present invention to solve the problem includes the following steps:

1) The storage unit stores the motor synchronous speed (N1), no-load operation electrical parameter iron consumption (P _Fe ), no-load current (IO) reference value and the maximum allowable speed reference value (Nm) of the pumping unit;

2) The motor enters the running state of continuous power supply, and the data acquisition unit collects the instantaneous value of the motor operating voltage and current in real time, and transmits the collected data to the computing unit;

3) The calculation unit performs calculations, evaluates and analyzes electrical parameters, determines the reference value of the electrical parameters at the starting point of the power-off operation of the motor, the power-off overtime limit (D _T1 ) and the working cycle (T) of the pumping unit, and stores them in the storage unit , set the initial value of the power-off timer;

4) The motor enters the power-on operation stage of the intermittent power supply operation state. The data acquisition unit collects the instantaneous value of the motor voltage and current in real time, and transmits it to the calculation unit;

5) The calculation unit performs digital calculation to obtain the random value of the electrical parameter during the power-on stage of the motor, and transmits it to the main control unit;

6) The comparator of the main control unit compares the random value of the electrical parameter with the reference value of the electrical parameter, and outputs a power-off control signal and a reset signal of the power-off timer when the power-off condition is met;

7) According to the received power-off control signal, the drive unit controls the action of the switch element to power off the motor, the motor enters the power-off operation stage, and the power-off timer starts counting;

8) The speed detection device starts to detect the motor speed (N) in real time, and transmits the data to the speed comparator (hardware or software);

9) The speed comparator compares the measured speed (N) with the high-speed reference (Nm). When it is higher than the high-speed reference, it outputs a "speed too high" signal to the main control unit, and the main control unit outputs a power-on signal to the drive unit, and the drive unit controls The action of the switching element causes the motor to be energized for a short period of time, and then continue to be powered off, and step 8) is executed, otherwise step 10) is executed;

10) The speed comparator compares the measured speed (N) with the synchronous speed (N1), and outputs a "close to synchronous speed" signal to the main control unit when the speed is close to the synchronous speed, and the main control unit outputs a power-on signal to the drive unit, and the drive unit controls The thyristor switch is turned on to energize the motor, and the voltage is gradually increased to the rated value by changing the firing angle, and step 4) is executed, otherwise step 11) is executed;

11) The power-off timer judges the power-off timing time (t). If the power-off time exceeds the power-off overtime limit (D _T1 ), it will output the "power-off timeout" signal to the main controller, and the main controller will output the power-on signal For the drive unit, the drive unit controls the action of the switching element to energize the motor, and executes step 2), otherwise executes step 8).

The present invention also provides an automatic control device for realizing a full-automatic control method for continuous operation of the motor of the beam pumping unit with intermittent power supply, including:

The data acquisition unit is connected with the power circuit of the motor, and collects the instantaneous value of the voltage and current when the motor is running;

The speed detection device detects the speed of the motor in real time and outputs it to the main controller;

The main controller, whose input signal end is connected to the signal output end of the data acquisition unit, and the output is connected to the drive unit, collects instantaneous values of voltage and current during continuous power supply, performs evaluation and analysis of electrical parameters, establishes reference values of electrical parameters, and determines power-on time and power-off time; in the power-on phase of intermittent power supply, continue to collect the instantaneous value of voltage and current, calculate the random value of electrical parameters, and determine whether the power-off condition is met; in the power-off operation phase, according to the speed detected by the speed detection device, Send a control signal to the drive unit to control the motor in real time;

The drive unit, the input end is connected to the main controller, the output end is connected to the switching element, receives the control signal from the main controller, and controls the on-off of the switching element;

The switch element is connected to the main power input circuit of the motor to control the power on and off of the motor.

Compared with the existing power supply mode of the pumping motor, the automatic control technology provided by the invention can realize the automatic control of the intermittent power supply of the motor of the beam pumping unit. Based on the data collected by the data acquisition unit, the main control unit effectively controls the switching elements in real time through the drive unit, controls the turn-on time and turn-on current of the motor power circuit, and monitors the speed through the protection device to effectively solve the problem. The problem of current impact and speed out of control in the intermittent power supply operation mode, so that the motor can effectively operate in the intermittent power supply operation state, and obtain a significant energy saving effect. At the same time, through the parameter identification in the state of continuous power supply, appropriate control parameters can be determined for pumping units with different balance conditions and load conditions, so that the automatic control device for intermittent power supply can control different types of pumping units Effectively control and track the load change of a specific pumping unit.

The present invention will be further described in detail below in conjunction with the accompanying drawings.

Description of drawings

Fig. 1 is the electrical main circuit diagram of the automatic control device for intermittent power consumption of the motor of the beam pumping unit of the present invention.

Fig. 2 is an electrical schematic diagram of the automatic control device of the present invention.

Fig. 3 is a structure diagram of a data acquisition circuit of the data acquisition unit of the present invention.

Fig. 4 is a schematic diagram of the pin connection of the main control unit of the present invention.

Fig. 5 is a schematic circuit diagram of the driving circuit of the present invention.

Fig. 6 is a block diagram of the circuit principle of the automatic control device of the present invention.

Fig. 7 is a block diagram of the circuit principle of the preferred embodiment of the present invention.

Fig. 8 is a flow chart of the automatic control method of the present invention.

Detailed ways

Please refer to Fig. 1. Fig. 1 is an electrical main circuit diagram of the automatic control device for the intermittent power consumption of the motor of the beam pumping unit. It is controlled by the contactor when the power supply is continuous, and it is controlled by the silicon controlled rectifier when the power supply is intermittent.

Please refer to Fig. 2, Fig. 6, Fig. 7, Fig. 2 is the electrical principle diagram of automatic control device of the present invention, Fig. 6 is the electrical principle block diagram of automatic control device, Fig. 7 is the circuit principle block diagram of preferred embodiment of the present invention. The current sensors CT1, CT2, and CT3 are inductively connected to the three-phase power supply loop, and the voltage sensors T1, T2, and T3 are directly connected to the power supply loop to collect the instantaneous values of the working current i and the working voltage u when the motor is continuously powered; The current signals CT1, CT2, CT3 and voltage signals A, B, and C of the current signal are sent to the data acquisition unit 100, and the data acquisition unit 100 adopts a data acquisition circuit (as shown in Figure 3, which can also be a built-in A/D circuit of the controller) to signal Processing, the processing result is delivered to main controller 200 (U0) (seeing Fig. 4, adopting Mega8535 single-chip microcomputer in this example, also can adopt other single-chip microcomputers), the input signal terminal IN1-IN6 of main controller 200 is respectively connected three-phase total The output terminals IN1-IN6 of the six data acquisition circuits are connected to the drive unit 160 (see FIG. 5 ). The trigger control signals PC1-PC7 from the main controller 200 are applied to the IN terminal of the drive unit 160 after passing through a typical optocoupler circuit and an oscillating circuit, and then applied to the IN terminal of the MOS transistor V The control pole, the output of the MOS tube V is divided into two outputs through the action of the pulse transformer B, which control two positive and negative parallel thyristors on one branch in Figure 1 respectively. The speed detection device 180 detects the rotation speed of the motor 210 in real time and outputs it to the main controller 200 .

Please refer to Fig. 6 and Fig. 7, the present invention realizes the automatic control method for continuous operation of the motor of the beam pumping unit with intermittent power supply and proceeds according to the following steps:

1) The storage unit 140 stores the synchronous speed of the motor (N1), the electrical parameter iron consumption (P _Fe ) of the no-load operation, the no-load current (IO) reference value and the maximum allowable speed reference value (Nm) of the pumping unit;

2) The motor enters the running state of continuous power supply, and the data acquisition unit 100 collects and tracks the instantaneous values of the motor operating voltage and current when the well conditions change in real time, and transmits the collected data to the computing unit 110;

3) The calculation unit 110 performs calculations, evaluates and analyzes electrical parameters, determines the input power reference value of the motor at the starting point of power-off operation, the power-off overtime limit (D _T1 ) and the working cycle (T) of the pumping unit, and stores them in The storage unit is used to set the initial value of the power-off timer;

4) The motor enters the power-on operation stage of the intermittent power supply operation state. The data acquisition unit 100 collects the instantaneous values of the motor voltage and current in real time, and transmits them to the computing unit 110;

5) The calculation unit 110 performs digital calculations to obtain the random value of the input electric power during the operation of the motor energization stage, and transmits it to the comparator 120 in the main controller;

6) The comparator 120 compares the input power random value with the input power reference value, and outputs a power-off control signal and a reset signal of the power-off timer when the power-off condition is satisfied;

7) The drive unit 160 controls the switching element 170 to power off the motor according to the received power-off control signal, and the motor enters the power-off operation stage, and the power-off timer starts counting after receiving the reset signal;

8) The speed detection device 180 starts to detect the motor speed (N) in real time, and transmits the data to the speed comparator 190;

9) The speed comparator 190 compares the measured rotational speed (N) with the high-speed reference (Nm), and when it is higher than the high-speed reference, outputs a "rotational speed too high" signal to the main control unit 130, and the main control unit 130 outputs a power-on signal to the drive unit 160 , the drive unit 160 controls the action of the switching element 170 to make the motor run in a short time (0.05T-0.2T), and then continue to power off, and perform step 8), otherwise perform step 10);

10) The speed comparator 190 compares the measured rotational speed (N) with the synchronous rotational speed (N1), and outputs a "close to synchronous speed" signal to the main control unit 130 when the rotational speed is close to the synchronous rotational speed, and the main control unit 130 outputs a power-on signal to the drive unit 160 , the drive unit 160 controls the thyristor switch 170 to enter the conduction state to energize the motor, gradually increase the voltage until the rated value by changing the firing angle, and perform step 4), otherwise perform step 11);

11) The power-off timer determines the power-off timing time (t). If the power-off time exceeds the power-off overtime limit (D _T1 ), it outputs a "power-off timeout" signal to the main controller 130, and the main controller outputs a power-on The signal is sent to the driving unit 160, the driving unit controls the switching element 170 to energize the motor, and executes step 2), otherwise executes step 8).

Step 4) may further include that the data acquisition unit 100 transmits the instantaneous data of the operating voltage and current of the motor 210 collected in real time to the comparator of the protection unit for comparison with the rated data of the circuit, and outputs a signal to activate the protection device when abnormal.

The electrical parameter reference value in step 1) can be input into the internal storage unit 140 of the main controller through the man-machine interface of the display device 150 for storage.

The present invention can be further understood by referring to FIG. 8 . Microcomputer power-on step (1) means that the main controller of the control system is powered on; step (2) inputs the rated power of the motor, the number of poles, the allowable maximum speed Nm of the pumping unit, and the synchronous speed N1 of the motor through the man-machine interface; Step (3), calculate iron consumption P _Fe during rated operation, and use it as the limit value of input power P1 during power-off control; step (4), start the motor manually; step (5), operate the motor in continuous power supply state, The acquisition system measures the three-phase voltage and current of the motor; step (6), the arithmetic unit of the main controller identifies the working cycle T of the pumping unit according to the collected data; step (7), calculates the power-off control criterion N _max , Δn , D _T1 ; where N _max is determined according to the maximum allowable speed Nm of the pumping unit, generally less than 1.3 times the rated speed, but not more than 70% of the maximum allowable speed Nm of the pumping unit; Δn can be taken as the synchronous speed N ₁ Within 10%; D _T1 can be taken as 0.6-0.9 times of the required time (duty cycle) of a work cycle; Step (8), calculate the input power P ₁ of motor according to the electrical quantity of gathering in the step (5); Step ( 9), judge whether P ₁ is less than P _Fe in step (3); Step (10), enter power failure state; Step (11), detect motor rotor speed N after power failure; Step (12), judge detected speed N Whether it exceeds N _max , if it exceeds the limit, then apply the speed limit measure step (13), the simplest speed limit measure is to power on for a short time in the generator state, such as power on (0.05～0.2)T; judge whether the rotor speed is close to the synchronous speed N ₁ (14) (the difference Δn between N and N ₁ is less than 10% of N ₁ ) is energized to run, the power supply is connected to the motor M through the thyristor switching element in Figure 1 (15), and the firing angle is gradually increased by changing the firing angle voltage until the rated value; measure the three-phase voltage and current after power-on, and calculate the input power P ₁ step (16); according to the measured voltage, current and power, judge whether the pumping unit is running normally, and whether the relay protection needs action steps ( 17); judge whether the power failure time exceeds the time limit determined by step (7); if step (18) exceeds the time limit, then connect the power electronic switch or AC contactor to make the motor connect to the power supply step (19); protection action, break Step (20) of turning on the power supply; step (21) of judging whether the determined power-off operation condition is satisfied.

The comparator used in the present invention can be a hardware comparator, or a built-in software comparator unit of the main controller.

The above scheme shows that when the motor is powered continuously, its operating parameters can be identified by detecting the voltage and current of the motor in real time. The basis is used to determine the number of power outages in a cycle and the electrical parameters for power outage operation control. During the power-on operation period of intermittent power supply, monitor whether the operating parameters of the motor of the pumping unit change significantly, so as to determine whether to return to the continuous power supply operation state. During the power-off operation period of intermittent power supply, the motor speed is detected in real time, and the power-off time and power-off mode are adjusted to keep it in the normal range. By properly controlling the conduction angle of the power electronic switch, the current impact is prevented when the power is re-energized. Intermittent power supply and protection are integrated so that it can stop and give an alarm in the event of power supply phase loss, motor disconnection, overload, overspeed, pump stop working, etc.

Claims (6)

1, a kind of full-automatic control method of beam pumping unit motor intermittent power supply continuous operation, it is characterized in that, this method comprises the following steps: 1) The storage unit stores the motor synchronous speed N1, the no-load operation electrical parameter iron consumption P _Fe no-load current IO reference value and the maximum allowable speed reference value Nm of the pumping unit; 2) The motor enters the running state of continuous power supply, and the data acquisition unit collects the instantaneous value of the motor operating voltage and current in real time, and transmits the collected data to the computing unit; 3) The calculation unit performs calculations, conducts electrical parameter evaluation and analysis, determines the electrical parameter reference value of the starting point of the power-off operation of the motor, the power-off overtime limit value D _T1 and the working cycle T of the pumping unit, stores them in the storage unit, and sets the power-off timer initial value; 4) After the motor enters the intermittent power supply operation state, the data acquisition unit collects the instantaneous values of the motor voltage and current in real time during the power-on operation period, and transmits them to the calculation unit; 5) The calculation unit performs digital calculation to obtain the random value of the electrical parameter when the motor is energized and running, and transmits it to the main control unit; 6) The comparator of the main control unit compares the random value of the electrical parameter with the reference value of the electrical parameter, and outputs a power-off control signal and a reset signal of the power-off timer when the power-off condition is satisfied; 7) According to the received power-off control signal, the drive unit controls the action of the switching element to power off the motor, and the motor enters the period of power-off operation, and the power-off timer starts counting; 8) The speed detection device starts to detect the motor speed N in real time, and transmits the data to the speed comparator; 9) The speed comparator compares the measured speed N with the high-speed reference Nm. When it is higher than the high-speed reference, it outputs a signal of "too high speed" to the main control unit, and the main control unit outputs a power-on signal to the drive unit. The motor is energized and operated within 0.05T-0.2T, and then continues to be powered off, and perform step 8), otherwise perform step 10); 10) The speed comparator compares the measured rotational speed N with the synchronous rotational speed N1, and outputs a "close to synchronous speed" signal to the main control unit when the rotational speed is close to the synchronous rotational speed, and the main control unit outputs a power-on signal to the drive unit, and the drive unit controls the switching element to enter Make the motor energized in the ON state, gradually increase the voltage until the rated value by changing the firing angle, and perform step 4), otherwise perform step 11); 11) The power-off timer judges the power-off timing time t. If the power-off time exceeds the power-off overtime limit D _T1 , it outputs a "power-off timeout" signal to the main control unit, and the main control unit outputs a power-on signal to the drive unit. The drive unit controls the action of the switching element to energize the motor, and executes step 2), otherwise executes step 8); Wherein, in the steps 3), 5), and 6), the electrical parameters are the input power P1 of the motor, the power factor COSφ or the power factor angle φ. 2. The full-automatic control method for continuous operation of the beam pumping unit motor with intermittent power supply as claimed in claim 1, characterized in that: in the step 3), the power-off overtime limit D _T1 takes the pumping unit working cycle 0.6-0.9 times. 3. The full-automatic control method for the continuous operation of the beam pumping unit motor with intermittent power supply as claimed in claim 1, characterized in that: said step 4) further comprises that the data acquisition unit collects the motor voltage and current in real time, Send it to the protection unit comparator to compare with the protection setting value, and output a signal to make the protection device operate when it is abnormal. 4. The full-automatic control method for beam pumping unit motor with intermittent power supply and continuous operation as claimed in claim 1, characterized in that in step 1), the reference value of electrical parameters is input into the storage unit through the man-machine interface for storage. 5. A fully automatic control device for continuous operation of the motor of a beam pumping unit with intermittent power supply, characterized in that it comprises, The data acquisition unit is connected with the power circuit of the motor, and collects the instantaneous value of the voltage and current when the motor is running; The speed detection device detects the speed of the motor in real time during the power-off operation stage, and outputs it to the main controller; The main controller, whose input signal end is connected to the signal output end of the data acquisition unit, and the output is connected to the drive unit, collects instantaneous values of voltage and current during continuous power supply, performs evaluation and analysis of electrical parameters, establishes reference values of electrical parameters, and determines power-on time and power-off time; in the power-on phase of intermittent power supply, continue to collect the instantaneous value of voltage and current, calculate the random value of electrical parameters, and determine whether the power-off condition is met; in the power-off operation phase, according to the speed detected by the speed detection device, Send a control signal to the drive unit to control the motor in real time; The drive unit, the input end is connected to the main controller, the output end is connected to the switching element, receives the control signal from the main controller, and controls the on-off of the switching element; The switch element is connected to the power circuit of the motor to control the power on and off of the motor; Wherein, the electrical parameter is the input power P1 of the motor, the power factor COSφ or the power factor angle φ. 6. The automatic control device for realizing the automatic control method for the intermittent power supply and continuous operation of the electric motor of the beam pumping unit according to claim 5, characterized in that: the switching element is connected in parallel by a thyristor and a contactor, and the control When the power supply of the motor is switched on and off, the contactor or the thyristor is used to connect the circuit when the power supply is continuous, and the circuit is connected by the silicon controlled rectifier when the power supply is intermittent.

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