CN108565837B - Broken rod protection method and motor protector - Google Patents
Broken rod protection method and motor protector Download PDFInfo
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- CN108565837B CN108565837B CN201810358587.1A CN201810358587A CN108565837B CN 108565837 B CN108565837 B CN 108565837B CN 201810358587 A CN201810358587 A CN 201810358587A CN 108565837 B CN108565837 B CN 108565837B
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- 238000000034 method Methods 0.000 title claims abstract description 20
- 230000001012 protector Effects 0.000 title claims abstract description 18
- 230000009471 action Effects 0.000 claims abstract description 9
- 238000005070 sampling Methods 0.000 claims description 16
- 238000004364 calculation method Methods 0.000 claims description 5
- 238000003825 pressing Methods 0.000 claims description 4
- 238000010248 power generation Methods 0.000 abstract description 6
- 238000011160 research Methods 0.000 abstract description 2
- 238000005086 pumping Methods 0.000 description 24
- 238000001514 detection method Methods 0.000 description 11
- 239000003921 oil Substances 0.000 description 10
- 230000005611 electricity Effects 0.000 description 6
- 230000008859 change Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 241001023788 Cyttus traversi Species 0.000 description 3
- 239000010779 crude oil Substances 0.000 description 3
- 230000006872 improvement Effects 0.000 description 3
- 238000013459 approach Methods 0.000 description 2
- 230000006870 function Effects 0.000 description 2
- 238000005381 potential energy Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 238000005299 abrasion Methods 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004422 calculation algorithm Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003129 oil well Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/08—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors
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- Control Of Electric Motors In General (AREA)
Abstract
The invention relates to a broken rod protection method and a motor protector, wherein the broken rod protection method comprises the following steps: detecting the power generation power and the power utilization power of the motor in one working cycle; and if the negative power content of the motor in one working cycle exceeds a setting value, judging that a rod breaking fault occurs, and executing corresponding protection action. The invention researches and discovers that the negative power content has obvious difference between normal and fault, and the rod breaking fault of the sucker rod can be diagnosed by utilizing the difference, thereby realizing accurate rod breaking fault judgment.
Description
Technical Field
The invention belongs to the field of motor protectors, and particularly relates to a broken rod protection method and a motor protector with a broken rod protection function.
Background
The pumping unit in oil field uses motor as power to drive the pumping rod to move up and down to pump out crude oil in crude oil production. The abrasion of the pumping rod can cause rod breaking fault during working, so that the pumping unit loses the pumping function and wastes electric energy.
At present, for a broken rod fault, the processing mode includes two types:
firstly, a broken rod fault is detected by adopting an indicator diagram method. The change of the load of the pumping unit can be known through the indicator diagram analysis, and then whether the sucker rod is normal or not is judged. However, the indicator diagram detection needs manual operation, the pumping unit is temporarily stopped to be provided with a sensor and an instrument during detection, time and labor are wasted, and the detection is performed once every month, so that the broken rod fault cannot be timely found and processed.
Secondly, an automatic online detection mode is adopted. The automatic on-line detection is realized by special equipment arranged on the oil pumping unit, the equipment always monitors the running state of the oil pumping unit, and once a fault is detected, a stop signal is automatically sent out and an alarm is given.
The automatic detection modes comprise current detection, power detection and power factor detection.
The limitations of current, power and power factor detection are between normal and broken rod, the variation of these parameters is not obvious, and the variation of underground conditions also brings the variation of motor current, these factors can interfere with the judgment of broken rod fault, and reducing this interference requires introducing more power parameters to find the relation between broken rod and these parameter values.
Disclosure of Invention
The invention aims to provide a broken rod protection method and a motor protector, which are used for solving the problem of inaccurate broken rod protection detection in the prior art.
The scheme of the invention comprises the following steps: a broken rod protection method comprises the following steps:
the motor protector detects the power generation power and the power consumption power of the motor in a working cycle, the power generation power is used as negative power, and the power consumption power is used as positive power, so that the content of the negative power is calculated;
and if the negative power content of the motor in one working cycle exceeds a setting value, judging that a rod breaking fault occurs, and executing corresponding protection action.
Aspects of the invention also include a motor protector comprising a processor and a memory, the processor executing a program stored in the memory to implement a method comprising:
detecting the generated power and the power consumption power of the motor in a working cycle, and calculating the content of the negative power by taking the generated power as the negative power and the power consumption power as the positive power;
and if the negative power content of the motor in one working cycle exceeds a setting value, judging that a rod breaking fault occurs, and executing corresponding protection action.
As a further improvement of the broken rod protection method and the motor protector, the calculation formulas of the negative power and the positive power of the motor in one working cycle are as follows:
wherein,
P－、P+the negative power and the positive power of the motor in one working cycle are shown, N is the number of sampling points in one working cycle, k is a sampling point count value, and uk and ik are sampling point voltage and current.
As a further improvement of the break rod protection method and motor protector, the negative power content NP is expressed as:
as a further improvement of the broken rod protection method and the motor protector, when the broken rod protection soft pressing plate is put into use and the negative power content of the motor in one working cycle exceeds a setting value, protection is carried out after protection delay.
The beneficial effects of the invention include: the invention researches and discovers that the negative power content of the motor power is obviously different between normal and fault, and the rod breaking fault of the sucker rod can be diagnosed by utilizing the difference, thereby realizing accurate rod breaking fault judgment.
Drawings
FIG. 1 is a protection logic diagram of embodiment 1;
FIG. 2 is a graph of normal well electrical balance;
FIG. 3 is a graph of faulty well electrical balance.
Detailed Description
The following description is made with reference to the accompanying drawings.
The basic concept of the method of the invention is as follows: and if the negative power content of the motor in one working cycle exceeds a setting value, judging that a rod breaking fault occurs, and executing corresponding protection action.
The method of the present invention may be integrated into a motor protector. For example in the form of software stored in the memory of the motor protector, which software is called by the processor of the motor protector when it is running, to implement the method of the invention.
Example 1
The working cycle refers to a working cycle of the pumping unit, and comprises an up stroke and a down stroke. The motor has two states of power utilization and power generation, the motor state is positive power, the generator state is negative power, and the proportion of power generation and power utilization can be defined by negative power content NP:
wherein P-P + is the negative power and the positive power of the motor in one working cycle.
P-、P+The negative power and the positive power of the motor in one working cycle are shown, N is the number of sampling points in one working cycle, k is a sampling point count value, and uk and ik are sampling point voltage and current.
In the embodiment, the motor protector continuously monitors the voltage and the current, and then, all sampling points in one working cycle are respectively superposed according to the positive power and the negative power; positive power sampling points are superposed to obtain P+The negative power sampling points are superposed to obtain P－Obtaining average generating power and average electric power, and calculating negative power content. Specifically, power is calculated in a cycle of 20ms (after AD sampling, average value processing is adopted for AD data, and a digital filtering algorithm is adopted, real part data and imaginary part data are calculated by FFT, active power, reactive power and the like are calculated), and positive active power and negative active power are accumulated in a working cycle (such as 12000 cycles) to obtain positive power and negative power.
After the oil pumping machine is balanced, the negative power content can be controlled within-6%. When the rod-breaking fault occurs to the oil pumping unit, the load of the motor is reduced due to the broken rod during the up stroke, and the oil pumping unit generates unbalance. The negative power content is obviously improved after the broken rod fault. Thus, a negative power content based approach can detect a broken rod fault.
As shown in fig. 1, when the breaking bar protection soft pressing plate is put into operation and the negative power content of the motor in one working cycle exceeds a setting value, a protection action is executed, namely tripping is performed after protection delay. The effects and principles of the present invention will be further described with reference to specific experimental data. When the rod of the pumping unit breaks down, the changes of voltage, current, power factor and the like are not obvious, and only the change of the negative power content is obvious in the whole process, so that the rod breaking fault can be judged through the change of the negative power content. The pumping unit in oil field is driven by motor to work and is divided into up stroke and down stroke according to the up-and-down motion of pumping unit horsehead and pumping rod. During the upstroke, the motor rotates and the balance weight moves downwards to drive the horse head and the sucker rod to move upwards, and the crude oil is pumped out. During the down stroke, the kinetic energy of the balance block at the bottom dead center and the falling potential energy of the sucker rod string make the horse head move downwards to drive the motor to rotate, and the motor generates electricity. When the balance block moves over the bottom dead center and rises from the low position to the high position, the balance block is driven by the motor, and the motor is converted from power generation to power utilization to drive the balance block to continuously rise to the top dead center so as to realize potential energy storage of the balance block and prepare for the next working cycle. Therefore, the oil pumping unit has two states of electricity utilization and electricity generation in a working cycle of the motor, the motor performs positive work, the generator performs negative work, and the proportion of electricity generation and electricity utilization is defined by the negative power content NP: the negative power content measures the electric energy utilization rate of the pumping unit, and obviously, the higher the value (absolute value, the same below), the lower the electric energy utilization rate. In order to improve the utilization rate of electric energy and avoid the loss caused by the back-and-forth conversion among electric energy, mechanical energy and electric energy, the smaller the negative power content is, the more ideal the weight and the position of the balance block need to be adjusted to adjust the balance of the oil pumping unit. Under the influence of complex underground conditions and system time variation, the negative power content can be controlled within-6% after the oil pumping unit is balanced. FIG. 2 shows a measured normal well electrical balance graph. In the figure, P is power, U is voltage, I is current, and PF is power factor. Normal well data are given in table 1. As can be seen from fig. 2, the power curve shows negative power at the downstroke, and table 1 shows that the negative power content NP is-4.88%.
TABLE 1 Normal well data
| U(V) | I(A) | P(kW) | PF | NP(％) |
| 215.7 | 36.4 | 3.021 | 0.423 | -4.88 |
And after the same oil well has a broken rod fault, the actually measured electric balance curve is shown in figure 2. The data for the failed well is shown in table 2.
As can be seen from fig. 3, when the pumping unit has a broken rod fault, the load of the motor is reduced due to the broken rod during the upstroke, and the pumping unit is unbalanced. At the moment, the light load accelerates the balance block to move downwards to drag the light-load motor to rotate so that the motor generates electricity, and the negative power of the power curve is increased when the power curve is in the upstroke. During the down stroke, the balance block cannot move upwards by means of the downward movement of the pumping rod due to rod breakage, and can only move upwards by means of the positive work of the motor, so that the negative power in the power curve disappears during the down stroke. As can be seen by comparing the graph data of the normal well and the fault well, the current data after the broken rod fault is not obvious in change, and the data with obvious difference only has negative power content, such as the broken rod N P which is-32.4% in the example, and N P which is-4.88% in the normal case. Thus, a negative power content based approach can detect a broken rod fault.
TABLE 2 faulty well data
As other embodiments, the negative power content NP may also be defined by other formulas, for example expressed as a ratio of negative to positive power.
In addition, P－And P+I.e. P, when the negative power and the positive power of the motor in one working cycle are defined as the accumulated negative power and the accumulated positive power in one working cycle－And P+The calculation formulas (1/N) after the equal sign are removed from the formulas (2) to (4), the obtained results are substituted into the formula (1), and the same calculation results as those in the embodiment 1 are obtained.
The above is a preferred embodiment of the present invention, but it should be understood that the above detailed description should not be construed as limiting the spirit and scope of the present invention, and obvious modifications or substitutions made by those skilled in the art based on the above embodiment still fall into the protection scope of the present invention.
Claims (6)
1. A broken rod protection method is characterized by comprising the following steps:
detecting the generated power and the power consumption power of the motor in a working cycle, and calculating the content of the negative power by taking the generated power as the negative power and the power consumption power as the positive power;
if the negative power content NP of the motor in one working cycle exceeds a setting value of-32.4%, judging that a rod breaking fault occurs, and executing corresponding protection action, wherein the negative power content NP is expressed as:
P－、P+negative power and positive power of the motor in one working cycle.
2. A method of protecting a broken rod according to claim 1, characterized in that: the calculation formula of the negative power and the positive power of the motor in one working cycle is as follows:
wherein,
n is the number of sampling points in a working cycle, k is the count of sampling points, uk，ikThe sampling point voltage and current.
3. A method of protecting a broken rod according to claim 1 or 2, characterized in that: when the broken rod protection soft pressing plate is put into operation and the negative power content of the motor in one working cycle exceeds a setting value, protection action is executed after protection delay.
4. A motor protector comprising a processor and a memory, characterized in that: the processor executes a program stored in the memory to implement the method of:
detecting the generated power and the power consumption power of the motor in a working cycle, and calculating the content of the negative power by taking the generated power as the negative power and the power consumption power as the positive power;
if the negative power content NP of the motor in one working cycle exceeds a setting value of-32.4%, judging that a rod breaking fault occurs, and executing corresponding protection action, wherein the negative power content NP is expressed as:
P－、P+negative power and positive power of the motor in one working cycle.
5. A motor protector according to claim 4 in which: the calculation formula of the negative power and the positive power of the motor in one working cycle is as follows:
wherein,
n is the number of sampling points in a working cycle, k is the count of sampling points, uk，ikThe sampling point voltage and current.
6. A motor protector according to claim 4 or 5 in which: when the broken rod protection soft pressing plate is put into operation and the negative power content of the motor in one working cycle exceeds a setting value, protection action is executed after protection delay.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810358587.1A CN108565837B (en) | 2018-04-20 | 2018-04-20 | Broken rod protection method and motor protector |
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| CN201810358587.1A CN108565837B (en) | 2018-04-20 | 2018-04-20 | Broken rod protection method and motor protector |
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| CN108565837B true CN108565837B (en) | 2020-12-25 |
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| CN2819642Y (en) * | 2005-09-07 | 2006-09-20 | 孙力 | Constant-power controller of beam oil sucker |
| CN201194310Y (en) * | 2008-03-24 | 2009-02-11 | 张生路 | Multifunctional distribution box for oil pump unit |
| CN102081117B (en) * | 2010-12-14 | 2015-07-08 | 大庆百米马流体控制系统有限公司 | Pumping unit power hand-held test instrument and application method thereof |
| CN104847309B (en) * | 2015-04-16 | 2017-12-01 | 山东爱特机电技术有限责任公司 | A kind of electric control device for oil pumping jack of capacitance energy storage |
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2018
- 2018-04-20 CN CN201810358587.1A patent/CN108565837B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104882622A (en) * | 2015-05-05 | 2015-09-02 | 中国东方电气集团有限公司 | Flow cell energy storage system control method and device |
| CN105375489A (en) * | 2015-12-14 | 2016-03-02 | 吕勇 | Power consumption management method, device and system |
| CN205429735U (en) * | 2015-12-14 | 2016-08-03 | 吕勇 | Power consumption management device and system |
| CN105909401A (en) * | 2016-06-27 | 2016-08-31 | 湖南大学 | Method for adjusting temperature difference power generation power matched loads in real time through variable heat transfer area |
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