CN111181445B - Self-starting control system and method for beam-pumping unit - Google Patents
Self-starting control system and method for beam-pumping unit Download PDFInfo
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- CN111181445B CN111181445B CN201811343851.0A CN201811343851A CN111181445B CN 111181445 B CN111181445 B CN 111181445B CN 201811343851 A CN201811343851 A CN 201811343851A CN 111181445 B CN111181445 B CN 111181445B
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- 238000005086 pumping Methods 0.000 title claims abstract description 20
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- 238000010248 power generation Methods 0.000 description 2
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P1/00—Arrangements for starting electric motors or dynamo-electric converters
- H02P1/02—Details of starting control
- H02P1/029—Restarting, e.g. after power failure
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P1/00—Arrangements for starting electric motors or dynamo-electric converters
- H02P1/16—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters
- H02P1/26—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters for starting an individual polyphase induction motor
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Abstract
The invention provides a self-starting control system and a self-starting control method for a beam-pumping unit, and belongs to the technical field of electric automatic control. The technical scheme is as follows: the intelligent self-starting control system of the beam-pumping unit comprises a voltage transformer, wherein the output end of the voltage transformer is connected with a signal conditioning unit, the analog quantity output end of the signal conditioning unit is connected with a sampling and holding circuit, the output end of the sampling and holding circuit is connected with an analog-to-digital converter, the digital output end of the analog-to-digital converter is connected with a CPU (central processing unit), the control output end of the CPU is connected with a self-starting execution element for controlling phase voltage signals, and the output end of the CPU is connected with the input end of the sampling and holding circuit to form a synchronous sampling signal clock acquisition loop. The invention has the beneficial effects that: when the motor stops running due to voltage sag or short-time interruption, if all starting conditions are met, the self-starting execution element sends out an automatic starting command, and the motor restarts running; and (4) independently controlling three phases.
Description
Technical Field
The invention relates to the technical field, in particular to an intelligent self-starting control system and method for a beam-pumping unit.
Background
Voltage sag is the instantaneous reduction of the effective value of the voltage to within 10% -90% of the nominal value at the system frequency, the duration of which is typically half the power frequency cycle to seconds. The voltage sag is mainly caused by voltage sag caused by faults, voltage sag caused by starting of a high-power induction motor and voltage sag caused by magnetizing inrush current of a transformer. Because the oil field distribution network has a complex structure and a large number of high-power devices and transformers, the problem of voltage sag is difficult to avoid, huge economic loss is brought, and the problem becomes the most serious power quality problem of the oil field distribution network at present.
Modern industrial equipment has become integrated and sophisticated with the development of science and technology, and the petrochemical industry has also adopted a large number of sophisticated equipment to increase the level of productivity. At present, the voltage sag control device is widely applied to production and life, and equipment which is seriously influenced by voltage sag comprises a switching power supply, an alternating current contactor, a PLC, a frequency converter, a photovoltaic inverter and the like. The alternating current contactor is used as electromechanical equipment for connecting or disconnecting a circuit, and is widely applied to an oil field power distribution network. At present, a beam pumping unit generally adopts a motor directly driven by a three-phase asynchronous motor or a permanent magnet synchronous motor and the like. When the voltage of the system drops temporarily or is interrupted for a short time, the alternating current contactor of the main loop of the motor is tripped at low voltage, so that the motor of the pumping unit is powered off; the mechanical inertia of the beam-pumping unit is large, and the phenomenon of power generation reversal can occur under the dragging of the mechanical inertia of the pumping unit after the motor loses power; the voltage change rule in the reverse power generation process is related to the position of the oil pumping unit at the moment of power failure. After the voltage sag is eliminated, the three-phase voltage on the network side is recovered to be normal, if the motor is directly started at the moment, because the amplitude and the frequency of the reverse electromotive force generated by the motor are different from the voltage on the network side, a larger impact current can occur, the success rate of superposition is low, and the service life of a contact of the switch device is influenced.
How to solve the above technical problems is the subject of the present invention.
Disclosure of Invention
The invention aims to provide an intelligent self-starting control system and method for a beam-pumping unit.
The invention is realized by the following measures: for a direct drive motor (a three-phase asynchronous motor or a permanent magnet synchronous motor) adopted by an oil field midstream beam type pumping unit, as the direct drive motor is dragged by larger mechanical inertia of the pumping unit after power failure, a reverse electromotive force can be provided, the motor can not be started immediately at the moment, otherwise, the deviation of the reverse electromotive force generated by the motor and the voltage of a power grid side can cause larger impact current. In order to meet the requirements of power failure caused by voltage sag and short-time interruption at the same time, the following implementation mode can be adopted, namely when the following conditions are met at the same time, the self-starting execution element sends out an automatic starting command:
(1) the three-phase voltage at the power grid side is recovered to be more than 0.9 times of rated voltage;
(2) the difference between the three-phase voltage at the power grid side and the voltage instantaneous value of the corresponding phase at the motor side is less than 1.1 times of rated voltage;
(3) the motor is tripped off when power is lost until the system side voltage recovers to be normal, and the time is less than 3-5 s;
the self-starting executing element adopts a direct current contactor and is independently controlled by three phases, namely when the voltage of a certain phase of power grid side and the voltage of a motor side meet the conditions, the corresponding direct current contactor is closed.
In order to achieve the purpose, the invention provides an intelligent self-starting control system of a beam-pumping unit, which comprises a voltage transformer, wherein the output end of the voltage transformer is connected with a signal conditioning unit, the analog output end of the signal conditioning unit is connected with a sample-and-hold circuit, the output end of the sample-and-hold circuit is connected with an analog-to-digital converter, the digital output end of the analog-to-digital converter is connected with a CPU, the control output end of the CPU is connected with a self-starting execution element for controlling a phase voltage signal, and the output end of the CPU is connected with the input end of the sample-and-hold circuit to form a synchronous sampling signal clock acquisition loop.
The voltage transformers comprise a voltage transformer on the motor side and a voltage transformer on the power grid side, and the voltage transformers on the motor side and the voltage transformers on the power grid side respectively measure the instantaneous values of three-phase voltage on the motor side and the instantaneous values of three-phase voltage on the power grid side in real time.
The self-starting execution element is a direct current contactor.
Further, in order to achieve the above object, the present invention further provides an intelligent self-starting control method of the intelligent self-starting control system for a beam-pumping unit, which specifically comprises: the three-phase voltage at the power grid side and the voltage of the corresponding phase at the motor side need to meet the following conditions:
(1) the three-phase voltage at the power grid side is recovered to be more than 0.9 times of rated voltage; the voltage sag is that the effective value of the voltage is instantaneously reduced to the range of 10% -90% of the rated value when the frequency of the system is reached, the duration time of the voltage sag is generally half of a power frequency period to several seconds, and the three-phase voltage at the power grid side is recovered to be more than 0.9 time of the rated voltage, namely the voltage sag disappears;
(2) the difference between the three-phase voltage at the power grid side and the voltage instantaneous value of the corresponding phase at the motor side is less than 1.1 times of rated voltage;
according to IEC 60038 standard voltage, the allowable deviation of the voltage of the motor in normal operation is +/-10%;
(3) the motor is tripped out when power is lost until the three-phase voltage on the system power grid side is recovered to be normal, and the time is less than 3-5 s;
according to the action time of protection and reclosing; if the time exceeds 3-5s, a continuous power failure will be caused.
And (3) when the voltage of the power grid side and the voltage of the motor side of a certain phase meet the conditions in the step (2), the phase sends an automatic starting command, and the corresponding direct current contactor is closed.
And the CPU respectively calculates whether the voltage of the motor side and the voltage of the power grid side of each phase meet the self-starting condition, if a certain phase voltage meets the self-starting condition, the CPU sends an automatic starting command, and the phase drives the corresponding direct current contactor to be closed.
The three-phase voltage of the motor side and the three-phase voltage of the power grid side obtained by the measurement of the voltage transformers of the motor side and the power grid side are converted into digital signals which can be used for digital acquisition through the signal conditioning unit; acquiring instantaneous values of three-phase voltage at the motor side and three-phase voltage at the power grid side at the same time through the sampling and holding circuit; the synchronous sampling signal of the sample and hold circuit is provided by the CPU.
The signal conditioning unit is used for amplifying, buffering or scaling the analog signal, so that the analog signal is used as the input of the analog-to-digital converter.
The invention has the beneficial effects that: the invention provides an intelligent self-starting method aiming at the condition that a direct drive motor of a beam pumping unit generates back electromotive force under the dragging of mechanical inertia after power failure to influence self-starting, when the motor stops running due to voltage sag or short-time interruption, if all starting conditions are met, a self-starting execution element sends out an automatic starting command, and the motor restarts running; the three phases are independently controlled, and the self-starting execution element adopts a direct current contactor, so that the action time is faster compared with an alternating current contactor; by the method, the impact current which may occur when the phase deviation of the three-phase voltage at the power grid side and the corresponding phase voltage at the motor side is large can be effectively avoided, the success rate of superposition is improved, and the influence of the impact current on the service life of the contact of the switch equipment is reduced.
Drawings
Fig. 1 is an electrical schematic structural diagram of an embodiment of the present invention.
Fig. 2 is a schematic diagram of an electrical principle structure of a motor side voltage, a grid side voltage and a corresponding voltage transformer in the embodiment of the invention.
Fig. 3 is a waveform of a grid side a-phase voltage and a motor side a-phase voltage when the motor loses power.
Wherein the reference numerals are: 1. a voltage transformer; 2. a signal conditioning unit; 3. a sample-and-hold circuit; 4. an analog-to-digital converter; 5. a CPU; 6. and starting the execution element automatically.
Detailed Description
In order to clearly illustrate the technical features of the present solution, the present solution is explained below by way of specific embodiments.
Referring to fig. 1-3, the present invention is: the invention also provides an intelligent self-starting control system of the beam pumping unit, which comprises a voltage transformer 1, wherein the output end of the voltage transformer 1 is connected with a signal conditioning unit 2, the analog quantity output end of the signal conditioning unit 2 is connected with a sampling and holding circuit 3, the output end of the sampling and holding circuit 3 is connected with an analog-to-digital converter 4, the digital output end of the analog-to-digital converter 4 is connected with a CPU 5, the control output end of the CPU 5 is connected with a self-starting execution element 6 for controlling phase voltage signals, and the output end of the CPU 5 is connected with the input end of the sampling and holding circuit 3 to form a synchronous sampling signal clock acquisition loop.
The voltage transformer 1 comprises a voltage transformer at the motor side and a voltage transformer at the power grid side, and the transformers at the motor side and the voltage transformers at the power grid side respectively measure the instantaneous values of three-phase voltage at the motor side and the instantaneous values of three-phase voltage at the power grid side in real time.
The self-starting executive component 6 is a direct current contactor.
Further, in order to achieve the above object, the present invention further provides an intelligent self-starting control method of the intelligent self-starting control system for a beam-pumping unit, which specifically comprises: the three-phase voltage at the power grid side and the voltage of the corresponding phase at the motor side need to meet the following conditions:
(1) the three-phase voltage at the power grid side is recovered to be more than 0.9 times of rated voltage; the voltage sag is that the effective value of the voltage is instantaneously reduced to the range of 10% -90% of the rated value when the frequency of the system is reached, the duration time of the voltage sag is generally half of a power frequency period to several seconds, and the three-phase voltage at the power grid side is recovered to be more than 0.9 time of the rated voltage, namely the voltage sag disappears;
(2) the difference between the three-phase voltage at the power grid side and the voltage instantaneous value of the corresponding phase at the motor side is less than 1.1 times of rated voltage;
according to IEC 60038 standard voltage, the allowable deviation of the voltage of the motor in normal operation is +/-10%;
(3) the motor is tripped out when power is lost until the three-phase voltage on the system power grid side is recovered to be normal, and the time is less than 3-5 s;
according to the action time of protection and reclosing; if the time exceeds 3-5s, a continuous power failure will be caused.
And (3) when the voltage of the power grid side and the voltage of the motor side of a certain phase meet the conditions in the step (2), the phase sends out an automatic starting command, and the corresponding direct current contactor is closed.
The CPU 5 respectively calculates whether the voltage of the motor side and the voltage of the power grid side of each phase meet the self-starting condition, if a certain phase voltage meets the self-starting condition, the CPU 5 sends an automatic starting command, and the phase drives to close the corresponding direct current contactor.
The three-phase voltage of the motor side and the three-phase voltage of the power grid side, which are obtained by measuring by the voltage transformers 1 of the motor side and the power grid side, are converted into digital signals which can be used for digital acquisition through the signal conditioning unit 2; acquiring instantaneous values of three-phase voltage at the motor side and three-phase voltage at the power grid side at the same time through a sampling and holding circuit 3; the synchronous sampling signal of the sample-and-hold circuit 3 is supplied from the CPU 5.
The signal conditioning unit (2) is used to amplify, buffer or scale the analog signal for input to the analog-to-digital converter 4.
The actual starting control method comprises the following specific processes: referring to fig. 3, taking the a-phase voltage as an example, U1 is a grid-side voltage waveform, and U2 is a motor-side voltage waveform; it can be seen that when the motor is de-energized, the amplitude and phase of the generated back electromotive force are different from the voltage of the power grid side; taking 0.025s as an example, the phases of the voltages at the two sides are opposite and the amplitude is large, the difference of the instantaneous values of the voltages is larger than 1.1 times of rated voltage, if the switch is closed at the moment, large impact current is generated, so that the success rate of reclosing is reduced, and the contact of the switching equipment is damaged; taking 0s as an example, the difference between the instantaneous values of the voltage on the power grid side and the voltage on the motor side is less than 1.1 times of the rated voltage, and the starting condition (2) is met; the voltage on the power grid side reaches more than 0.9 times of rated voltage, and the condition (1) is met; and (4) assuming that the time from the power loss jump of the motor to the recovery of the network side voltage to the normal voltage is less than 3-5s, and satisfying the condition (3).
At this point, the self-starting actuator 6 issues an automatic starting command and the corresponding dc contactor is closed.
The technical features of the present invention which are not described in the above embodiments may be implemented by or using the prior art, and are not described herein again, of course, the above description is not intended to limit the present invention, and the present invention is not limited to the above examples, and variations, modifications, additions or substitutions which may be made by those skilled in the art within the spirit and scope of the present invention should also fall within the protection scope of the present invention.
Claims (6)
1. The self-starting control system of the beam-pumping unit is characterized by comprising a voltage transformer (1), wherein the output end of the voltage transformer (1) is connected with a signal conditioning unit (2), the analog output end of the signal conditioning unit (2) is connected with a sampling and holding circuit (3), the output end of the sampling and holding circuit (3) is connected with an analog-to-digital converter (4), the digital output end of the analog-to-digital converter (4) is connected with a CPU (5), the control output end of the CPU (5) is connected with a self-starting execution element (6) for controlling a phase voltage signal, and the output end of the CPU (5) is connected with the input end of the sampling and holding circuit (3) to form a synchronous sampling signal clock acquisition loop;
the voltage transformer (1) comprises a motor side voltage transformer and a power grid side voltage transformer, and the motor side transformer and the power grid side voltage transformer respectively measure a motor side three-phase voltage instantaneous value and a power grid side three-phase voltage instantaneous value in real time; the self-starting execution element (6) is a direct current contactor;
when the control system is started automatically, the three-phase voltage of the power grid side and the voltage of the corresponding phase of the motor side need to meet the following conditions:
(1) the three-phase voltage at the power grid side is recovered to be more than 0.9 times of rated voltage;
(2) the difference between the three-phase voltage at the power grid side and the voltage instantaneous value of the corresponding phase at the motor side is less than 1.1 times of rated voltage;
(3) the motor is tripped off when power is lost until the system side voltage recovers to be normal, and the time is less than 3s or 5 s;
when the voltage of the power grid side and the voltage of the motor side of a certain phase meet the conditions, the phase sends an automatic starting command, and the corresponding direct current contactor is closed.
2. A self-starting control method for a beam-pumping unit is characterized in that when a control system is self-started, the three-phase voltage at the power grid side and the voltage corresponding to the motor side need to meet the following conditions:
(1) the three-phase voltage at the power grid side is recovered to be more than 0.9 times of rated voltage;
(2) the difference between the three-phase voltage at the power grid side and the voltage instantaneous value of the corresponding phase at the motor side is less than 1.1 times of rated voltage;
(3) the motor is tripped off when power is lost until the system side voltage recovers to be normal, and the time is less than 3s or 5 s;
when the voltage of the power grid side and the voltage of the motor side of a certain phase meet the conditions, the phase sends an automatic starting command, and the corresponding direct current contactor is closed.
3. The method according to claim 2, characterized in that a system for realizing the method comprises a voltage transformer (1), the output end of the voltage transformer (1) is connected with a signal conditioning unit (2), the analog quantity output end of the signal conditioning unit (2) is connected with a sample-and-hold circuit (3), the output end of the sample-and-hold circuit (3) is connected with an analog-to-digital converter (4), the digital output end of the analog-to-digital converter (4) is connected with a CPU (5), the control output end of the CPU (5) is connected with a self-starting execution element (6) for controlling phase voltage signals, and the output end of the CPU (5) is connected with the input end of the sample-and-hold circuit (3) to form a synchronous sampling signal clock acquisition loop.
4. A method according to claim 3, characterized in that the CPU (5) internally calculates whether the voltage of the motor side and the grid side of each phase meets the self-starting condition, respectively, and if a certain phase voltage meets the self-starting condition, the CPU (5) sends an automatic starting command, and the phase drives the corresponding dc contactor to close.
5. The method according to claim 3, characterized in that the motor side and grid side three-phase voltages measured by the motor side and grid side voltage transformers (1) are converted into digital signals available for digital acquisition by the signal conditioning unit (2); instantaneous values of the three-phase voltage at the motor side and the three-phase voltage at the power grid side at the same time are obtained through the sampling and holding circuit (3); the synchronous sampling signal of the sample hold circuit (3) is provided by a CPU (5).
6. A method according to any of claims 3-5, characterized in that the signal conditioning unit (2) is arranged to amplify, buffer or scale an analog signal for the input of the analog-to-digital converter (4).
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| CN201811343851.0A CN111181445B (en) | 2018-11-13 | 2018-11-13 | Self-starting control system and method for beam-pumping unit |
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| US7038423B2 (en) * | 2004-05-07 | 2006-05-02 | Bay Controls, Inc. | Apparatus and method for ride through for AC induction motors |
| JP2006197745A (en) * | 2005-01-14 | 2006-07-27 | Mitsubishi Electric Corp | Controller for induction motor |
| CN100411296C (en) * | 2005-06-30 | 2008-08-13 | 东方日立(成都)电控设备有限公司 | Instantaneous power cut restaring method and apparatus for frequency change speed regulating system |
| CN205725557U (en) * | 2016-05-11 | 2016-11-23 | 安徽立卓智能电网科技有限公司 | A kind of feeder reactance voltage disturbance power-supply system |
| CN106786340B (en) * | 2016-12-02 | 2019-03-08 | 江苏国网自控科技股份有限公司 | A kind of voltage shock avoiding decompression opening device and its control method again |
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