JP2001245496A - Method and device for adjusting counter balance of pump jack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely find an optimal counter balance value of a drive system of a pump jack in actual working conditions of the pump jack. SOLUTION: In the counter balance (C balance) adjusting method of the pump jack of a induction motor drive, the pump jack is operated for n cycles with arbitrary C balance weight. In up stroke(US) and in down stroke(DS), each average of the secondary current momentary maximum value (the secondary maximum average) is found. Weight of 49, 50, C balance are changed, then each secondary maximum average in US and DS is found. By means of the optimal C balance arithmetic unit 53 by a regression line equation method, it is found that the regression line equation to the US secondary current maximum value and the change of C balance weight by using the secondary maximum average in US, and it is found that the regression line equation to the DS secondary current maximum value and the change of C balance weight by using the secondary maximum average in DS. The optimal C balance weight is found from the intersection.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a counterbalance of a pump jack driven by an induction motor whose speed is controlled by a variable voltage and variable frequency power supply, and more particularly to a counterbalance for estimating and calculating an optimum value of the counterbalance. For adjusting the weight or radius.

[0002]

2. Description of the Related Art Conventionally, as a means for increasing the production of crude oil in a beam pump oil well, it is necessary to respond to changes in the oil well situation, and in particular, to accurately detect a pump-off condition to prevent a serious failure of a sucker rod or a downhole pump. Efforts have been made to protect and provide continuous production of crude oil. The basic operation of the pump jack drive system in this case is that the rod displacement moves from the down-stroke end to the up-stroke during the process in which the pump discharge valve closes and the suction valve opens, and the pump load increases, and the pump load increases. Rod load increases. In the next discharge cycle, when the rod shifts from the up stroke end to the down stroke, the pump suction valve closes and the discharge valve opens to shift to the discharge cycle.At this time, the pump load decreases and the sucker rod load decreases. Reduce. Such a pumping operation with suction and discharge as one cycle is repeated, but recently, variable speed driving has been used instead of the conventional constant speed driving of the induction motor for driving the pump jack, In order to drive the pump jack at high speed, the cycle time of the pump jack is shortened.

[0003] A typical method is to increase the speed when the load on the pump jack is light to make the drive motor a constant output drive system. For example, an inverter is used as the drive power source of the motor, and the voltage is higher than the rated frequency. Is kept constant, and constant output control is performed approximately. 9 and 10
FIG. 5 is a characteristic diagram showing a relationship between a pump stroke and a sucker rod load according to such a conventional inverter control method. FIG. 9 shows a case in which the pump is driven at a pump stroke speed of 100%, but the pump load (2) is suddenly loaded (UP) and unloaded (DOW) by the suction and discharge cycles.
N), it can be seen that the sucker rod load (3) is pulsating. Also, the pump load (2) is
It can be seen that in the section where P is performed (the upper end portion of the rectangular waveform), a peak load exceeding the rated rod load is applied as the rod load (3). FIG. 10 shows an example in which the pump stroke speed is doubled (200%). The pulsation amplitude of the sucker rod load (3) is further larger than that of FIG. 9 and far exceeds the rated rod load. This indicates that the pulsation amplitude increases as the speed increases. There are some reports that the sucker rod load reaches 1.6 times or more when the pump speed is increased twice, so if you want to increase the pump jack speed and shorten the cycle time in order to increase oil well productivity, Therefore, means for suppressing an increase in the sucker rod load is required. In the drive system of the pump jack, a counterbalance for canceling the sucker rod load is usually used mainly for the purpose of reducing the drive capacity. The counter balance is designed to be optimal based on the sucker rod torque converted to the reduction gear shaft by the sucker rod load and the torque coefficient determined by the pump jack mechanism at the time of design. In other words, the optimal counterbalance radius and the optimal counterbalance weight are determined based on the design specifications, so that the design value and the actual value of the sucker rod load are different or the depth of the pump well is changed. In this case, it is necessary to readjust the counter balance to the optimum value.

[0004]

However, in the above conventional example, when the counter balance is not properly adjusted, the maximum load of the motor during the up stroke and the down stroke is significantly different, and the drive system is overloaded. In an extreme case, the driving torque may be insufficient and driving may not be possible in an extreme case. However, in order to adjust the counter balance to an optimum value, the sucker rod load data which is closer to the actual value is obtained. The problem is that there is no other way than to obtain the optimal adjustment value based on the operation results by changing the counterbalance radius or the counterbalance weight by trial and error after obtaining the data and designing calculation based on the data. was there. Therefore, the first invention of the present invention is to calculate and estimate an optimum counter balance value using a regression equation, and thereby to reduce the counter balance value under actual use conditions without requiring detailed sucker rod load data. The present invention provides a method and an apparatus for adjusting the counterbalance of a pump jack capable of performing an optimal counterbalance adjustment capable of reducing the peak torque applied to the drive system, and greatly reducing the required maximum torque of the motor. The purpose is. Further, according to the second invention of the present invention, the value of the counterbalance is quickly determined by calculating and estimating the pump load by a simple configuration that does not require changing the weight or radius of the counterbalance, and the drive system An object of the present invention is to provide a method and an apparatus for adjusting the counterbalance of a pump jack, which can reduce a peak torque applied and reduce a required maximum torque of an electric motor.

[0005]

Means for Solving the Problems To achieve the above object,
Therefore, the first aspect of the present invention provides a variable voltage, variable frequency
Induction motor drive configured to control speed
In the pump jack counter balance adjustment method,
Pump at any counterbalance weight or radius
Operate the jack for at least n cycles (n ≧ 1)
Electric drive for each of stroke and downstroke
Means for detecting and storing the maximum value of the instantaneous secondary current of the machine, n
The average for the n maximum values obtained by cycle operation
Average (I_{U 1} , I_{D 1} Means), and the pump
Change the weight or radius of the jack counterbalance
Operation for at least n cycles, and
Upstroke and downstroke under counterbalance
The average value (I) of the maximum values of the n secondary currents during the stroke_{U 2} ,
I_{D 2} ) Is provided, and two
Average value of the maximum value of the next current (I_{U 1} , I_{U 2} )
Upstroke secondary current maximum value and counterbalance weight
Calculate the regression line equation for the change of the amount or radius, and
On the other hand, the average value of the maximum secondary current during downstroke
(I_{D 1} , I_{D 2} ) By the downstroke secondary current
Maximum and counter balance for weight or radius changes
Regression line equation
Special counterbalance weight or radius.
It is a sign. Also, the invention described in claim 2 is
To the counterbalance adjustment method of the pump jack described in 1.
The pump jack counterbalance weight or
Changes the radius at least m times (m ≧ 2), and
The secondary current during upstroke.
Average value of maximum value (I_{U 1} , I_{U 2} , I_{U 3} , ..., I_{U m}
 ), The maximum value of the upstroke secondary current and the cowl
Regression line for changes in weight or radius
Equation, and on the other hand, the maximum secondary current during downstroke.
Average of large values (I_{D 1} , I_{D 2} , I_{D 3} , ..., I
_{D m} ) Indicates the maximum value of the downstroke secondary current and the
Regression line for changes in weight or radius
Find the equation and determine the optimal counter
It is characterized by determining the lance.

[0006] Further, the invention according to claim 3 is based on claim 1.
In the method of adjusting the counter balance of the pump jack according to the second aspect, the instantaneous value of the secondary current with respect to each stroke time during the upstroke and downstroke operations is determined by at least one or more cycles of the operation of the pump jack. Means for detecting sampling, storing the detected current value and the corresponding sampling time as a pair in a table, means for detecting the upstroke end time, and calculating the secondary time during the upstroke from the value of the table. Means for detecting the current maximum value (I _UP ) and its time (hereinafter referred to as the secondary current maximum value time), and from the table, from the maximum time of the secondary current during the upstroke. Means for detecting an instantaneous secondary current value (IDX) of a downstroke time equal to the time to the upstroke end is provided, and an algebraic sum of the current value (IDX) is provided. I _UP + I _DX ) is used to estimate the pump load torque, and to estimate a value obtained by subtracting 1/2 from the maximum polyside rod torque as the optimum counterbalance torque.

[0007] The invention described in claim 4 is the first invention.
The counter bar of the pump jack according to any one of claims 1 to 3,
In the lance adjustment method, the up stroke and the down stroke
Calculates the difference between the average values of the maximum secondary current during a troke
And determine whether the counterbalance is appropriate or not based on the calculation result.
The program for determining the optimal value of the counter balance
It is characterized by doing. Further, according to claim 5,
A pump jack according to any one of claims 1 to 4.
Counter balance adjustment method.
When performing the estimation calculation for determining the optimal value of the
Switch the switch to the test side to set the pump jack speed.
The speed is set lower than the rated stroke speed.
are doing. The invention according to claim 6 is the invention according to claims 1 to
5. The pump jack counter rose according to any one of 5.
Determine the optimal value of the counter balance in the
The program uses the regression linear equation method and the pump load
Select and execute the estimation method in the test mode.
It is characterized by. The invention according to claim 7 is
Variable voltage and variable induction motor driving pump jack
Hump jack whose speed is controlled by a frequency power inverter
Counter balance to reduce drive capacity of drive system
For pump jack counter balance adjustment device
The counter balun according to the input signal from the constant
Program to start the program for determining the optimal value of
Means and a program for determining an optimum value of the counter balance
Is activated and the control switch is switched to
Test speed setting means to set a speed lower than the peak speed
And the optimal value of the counter balance by selecting the test mode
Select a method using the regression line equation of the decision program.
Strike mode selection means and counter balance weight or half
Counter balance setting means for setting and changing the diameter
Update based on the set and changed counter balance.
Each drive during push stroke and down stroke
Means for detecting and storing the maximum value of the instantaneous secondary current of the motor
And an average value detecting means for obtaining each average value with respect to the maximum value.
And the counter balance by calculating the difference between
Counter balance judgment means for judging whether the
The average value of the maximum secondary current during the upstroke
Is the maximum value of the up-stroke secondary current and the counter balun
Find the regression linear equation for the change in
Down due to the average of the maximum secondary current during
Regarding the change of the maximum value of the low secondary current and the counter balance
Find the regression line equation
When performing calculations to determine weight or radius
It has an appropriate counter balance calculating means. Also, billing
The invention according to claim 8 provides a pump jack according to claim 7.
Test mode selection in the counter balance adjustment device
Program for determining the optimal value of the counter balance
Test mode selection means for selecting a method based on load estimation
And each stroke during upstroke and downstroke operation.
Sampling of the instantaneous value of the secondary current with respect to the trooke time
Detects the detected current value and the corresponding sampling time.
Storage means for storing in a table as a pair;
Stroke end time detection
And the secondary during upstroke from the values in the table
Current maximum value (I_UP ) And the time detector that detects that time
A step and a second during the upstroke from the table.
Time from maximum current value time to end of up stroke
Instantaneous during the downstroke time with an elapsed time equal to
Time value (I_{D X}), And an algebraic sum of the current values
The pump load torque is estimated by
1/2 of luk was subtracted from the maximum polyside rod torque
Value to estimate the value as the optimal counterbalance torque
It has a counter balance calculating means.

According to this structure, the induction motor for driving the pump jack is provided with a variable voltage, variable frequency power supply inverter.
The present invention provides two inventions which are configured so that speed can be controlled by a motor and provided with means for detecting and storing the speed of the motor and the instantaneous value of the secondary current, and calculating the optimum counter balance by calculating these data. According to the first invention, the pump jack is operated for a plurality of cycles or more under different known counterbalance settings, and this operation causes the maximum secondary current instantaneous value and the counterbalance data to be upstroke. A regression linear equation for estimating the change in the counterbalance with respect to the change in the secondary current maximum value and a regression linear equation for estimating the change in the counterbalance with respect to the change in the secondary current maximum value during downstroke are obtained. The optimum counter balance value is obtained from the intersection. According to a second aspect of the present invention, the value of the gearbox torque during the maximum upstroke operation is set as a known value, and in an arbitrary counter balance setting, the pump jack is operated at a plurality of cycles or more to perform the upstroke operation. Data of the maximum value of the instantaneous current value of the secondary current and the time at which the maximum value is obtained are obtained. With this data, the instantaneous secondary current value at the time of downstroke with the upstroke end as the axis of symmetry is obtained. The pump load is estimated based on the algebraic sum of the values read out, and then the 1/2 is subtracted from the maximum gearbox torque to obtain the optimum counter balance value. Therefore, the first invention involves the actual work of setting different counter balances,
The test operation of the pump jack alone has the advantage that the optimum counter balance can be accurately determined without the need for detailed sucker rod load data under the actual pump jack operating conditions. Accurate counterbalance adjustment is possible when it is difficult to obtain gearbox torque data. In the second invention, it is necessary to grasp the maximum gab box torque, but there is an advantage that the setting work of the counter balance is unnecessary for the test operation, so that the simple operation such as the initial operation of the pump jack is performed. This is effective as a method of adjusting the counter balance.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a pump jack counter balance adjusting device to which a vector control inverter of an induction motor according to a first embodiment of the present invention is applied. FIG. 2 is a control block diagram of the counter balance adjusting device shown in FIG. FIG. 3 is an explanatory diagram showing the relationship between the sucker rod load and the secondary current of the electric motor by computer simulation of the pump jack shown in FIG. FIG. 4 is an explanatory diagram of a regression linear equation calculated by the optimum counter balance calculator shown in FIG. FIG. 5 is a flowchart of the optimal counter balance weight calculation shown in FIG. In FIG. 1, reference numeral 1 denotes an electric motor for driving a pump jack, 2 denotes a speed detector directly connected to the electric motor 1, 3 denotes a control unit of a vector control inverter of the electric motor 1, and 4 denotes a counter balance adjusting device.

[0010] 31 is inverted - a linear commander of motor control unit 3, accelerated the set speed reference N _P is the output of counter balancing device 4 inside - limit bets, the speed of the motor reference N _S It works to convert to. This speed reference N _S
Is the actual speed detected by the speed detector 2 and its output N _i
The deviation is amplified by the speed regulator 32, and the secondary current command I _{2 S} is output to the output side. The motor current is detected by the current transformer 35, and only the secondary current component is detected as I ₂ by the vector calculator 36,
Compared to I _{2 S.} The deviation is amplified by the current regulator 33, and the PWM controller 34 adjusts the pulse width of the voltage applied to the electric motor 1 to serve to supply a secondary current necessary for driving the load. In this way, the motor speed is automatically adjusted so that the actual speed becomes substantially equal to the speed reference. That is, the inverter control section 3 shows a configuration example of a vector control inverter having a known current minor loop. However, in FIG. 1, necessary for vector control, the control circuit of磁速component current I _M of the electric motor are known, the counter balancing device of the present invention, since it is not directly related, not shown for simplicity Have been.

FIG. 2 is a detailed block diagram of the counter balance adjusting device shown in FIG. 1. Reference numeral 41 denotes an instantaneous secondary current value and time for each downstroke time of the pump jack, which are detected and stored. In the memory MEMO1, the I _{2 D} (t) during the downstroke is sampled at high speed every Δt time and the value is stored. Similarly, reference numeral 42 denotes a memory MEMO2 for sampling detection and storage of I _{2 U} (t) during the upstroke, and reference numerals 42 and 43 denote maximum values I of the respective secondary currents from the storage data of MEMO1 or MEMO2. _This is a maximum value calculator for calculating _{2 DP} (t) and I _{2 UP} (t), and the result is stored in memory tables 45 and 46. A timing pulse generator 47 generates a constant timing pulse Δt for sampling detection. The elapsed time signal generator 48 integrates this Δt to generate an elapsed time signal of the instantaneous value of the secondary current stored in the memory 41 or 42. Upstroke or downstroke
The data of the mark is the contact of the detection switching relay 61, DET /
It is taken into the 42 or 41 side by C1 and DET / C2. Although not shown, the signal generator 48 is configured to be momentarily reset each time this switching is performed. Therefore, the memories 42 and 41 store ΣΔt starting from the switching time point and the instantaneous value of the secondary current every Δt time.

Reference numerals 49 and 50 denote average value calculators, which calculate the average value at a predetermined timing based on the data in the memory tables 45 and 46, and compare the results with a comparator 51. I do. For example, in the case where k memory tables 45 and 46 are prepared, when k data are full, these data are transferred to computing units 49 and 50,
(ΣI _{2 DP} (t)) / k = I _{2 DM} and (ΣI _{2 U}
Calculate _P (t) / k = I _{2 UM} . Comparator 51
_Are the outputs I _{2 DM} and I _{2 UM} of the average calculators 49 and 50
Is calculated, and the result is displayed on the detection display 52 as appropriate or inappropriate for counterbalance. In this case, the display 52 has a function of directly displaying the difference between I _{2 DM} and I _{2 UM} , and a function of displaying an alarm on the display 52 as an improper counter balance when a preset value is exceeded. Having. Reference numeral 53 denotes an optimum counter balance calculator incorporating software for estimating and calculating the optimum value of the counter balance, and outputs its output to a display 54 as described later. Reference numeral 55 denotes a stroke time calculator for calculating a 1/2 stroke time. The pump time is taken as Ni, and the speed and a reduction ratio set as a mechanical constant and a setting data of a rated stroke speed are obtained. From the data, １ ／ stroke time (T _S
/ 2) is calculated. The result is divided by Δt to obtain 1 /
The two-stroke time is converted to a Δt base and set in the stroke calculator 55. The output of 55 is compared with the output of 48 for calculating ΔΣt by the comparator 56. When the value of ΔΣt reaches the stroke value set to 55, the output of the comparator 56 is set to “1”. Every time the output of the comparator 56 becomes "1", the sequence storage memory 60 is turned "OFF". That is, the detection switching relay
The memory 41 stores the instantaneous value of the secondary current during the downstroke operation from the time when 61 is turned on, and the instantaneous value of the secondary current during the upstroke operation from the time when the detection switching relay 61 is turned off. Or, it can be taken into 42. The sequence storage memory 60 is provided with a changeover switch 59 provided at the input side of the switch 60. The reference point signal generator 58 for software processing or the stroke for detecting the stroke position of the pump jack is provided. It is operated by any of the signals of the position sensor 20.

The stroke position sensor 20 is, for example, a mechanical, magnetic, or optical sensor that detects the crank angle of the pump jack. This signal indicates that the stroke position of the pump jack is at the up end. Then, the sequence storage memory 60 is turned ON. This signal is stored in the sequence storage memory 60, and turns on the detection switching relay 61. As described above, the relay 61 is turned on, and the capture of the instantaneous secondary current value during the downstroke operation is started. The storage signal at the position stored in the sequence storage memory 60 is released when the comparator 56 becomes "1" at the end of the downstroke. With this release, the relay 61 is turned off, and the acquisition of the instantaneous secondary current value during the upstroke operation is started. Hereinafter, this operation is repeated. In other words, with such a configuration and control, the instantaneous value of the secondary current of the motor during the downstroke operation is changed by the "OFF" of the detection switching relay 61 when the detection switching relay 61 is turned "ON". The instantaneous value of the secondary current of the motor during the upstroke operation can be detected. The reference point signal generator 58 is a software-based reference point signal generator prepared for the case where it is difficult to install the stroke position sensor 20 due to restrictions on the mechanical structure and the like. The principle is that the zero cross point A 'of the next current is determined by the net torque of the reducer shaft (sucker rod torque-counter balance torque) of the pump jack, and the net torque of the reducer is fixed to a special crank angle determined by the mechanical constant. The reference signal generation circuit described above. That is, the point A 'is detected as the zero-cross point of the motor secondary current instantaneous value of the up-stroke, and the time TPO = (Δθ / Vθ) to reach the up-stroke end point with reference to this point (where Δθ: zero-cross The phase difference angle between the crank angle corresponding to the point A 'and the crank angle at the end of the upstroke, Vθ: average crank rotation speed = 360 ° / TS = 6.0 × S, is calculated and estimated from the equation. If the zero-cross point A 'can be detected, the stroke position can be specified as reaching the up-stroke end after the time TP0. 62
Is a speed setting device for setting the normal operation speed of the pump jack, and 63 is a speed setting device for setting the speed of the pump jack when the optimum counter balance calculator 53 is operated. The speed setting unit 63 sets the speed of the pump jack when estimating and calculating the optimum value of the counter balance, and is lower than the rated stroke speed, for example, 25%.
Set to speed. This is because the influence of the pulsation of the secondary current of the motor due to the dynamic characteristics of the sucker rod system is taken into account in the estimation calculation of the optimum counter balance. The selection of the speed setting units 63 and 62 is made by the contact COS / C1 of the control changeover switch 64. Switch 64 at the same time
The signal of "1" is input from the constant device 57 to the optimum counter balance calculator 53 through the contact COS / C2, and the program of the calculator 53 is started.

Next, the operation will be described. Here, the adjustment of the counter balance means the adjustment of the maximum counter balance torque, and the maximum counter balance torque is represented by the rotation radius of the counter balance (LC) × the weight of the counter balance (WC B). That is, the adjustment of the counter balance of the present invention is performed by adjusting the rotation radius (LC
) Or adjusting the counterbalance weight (WC B). Hereinafter, for simplicity, description will be made by adjusting the weight of the counter balance. FIG.
Pump jack rated stroke speed 11.3 stroke
Pump / minute, pump unit: API C114-143
In 64 pump units, counterbalance load =
Design value (hereinafter referred to as 100% counterbalance weight)
And the counterbalance load = 1 of the design value
40% (hereinafter referred to as 140% counterbalance weight)
, The sucker rod torque and the motor secondary current when the motor is operated at the rated speed are obtained by computer simulation. The pump jack stroke position is also shown in the figure. FIG.
At the time of 0% counter balance weight, FIG.
It is a characteristic at the time of% counter balance weight.

By comparing FIGS. 3 (a) and 3 (b), when the counterbalance weight is set to 140%, the maximum value of the secondary current of the motor at the time of the upstroke is larger than the counterbalance. It can be seen that the motor secondary current at the time of downstroke is changed from the sign to the secondary current on the electric torque side, which is smaller than the case of 100% by weight. In other words, if the counterbalance weight is further increased beyond 140%, it is expected that the maximum value of the motor secondary current during the upstroke and the maximum value of the motor secondary current during the downstroke can be made equal. You. That is, if the counterbalance weight is variously changed and the counterbalance weight is regression-analyzed with respect to the change in the maximum value of the secondary current of the motor during the upstroke and the downstroke, the motor secondary current is obtained. The counterbalance weight at which the maximum value of Eq. The first embodiment of the present invention is based on this principle.

FIG. 4 shows, by computer simulation, a change in the maximum value of the motor secondary current when the weight of the counterbalance is changed five times, and the results are plotted. It is an equation. In FIG. 4, the Y-axis gives the peak current ratio of the motor, IP / IPbase, and the X-axis gives the counter balance weight ratio, WCB / WCBd. In this case, IPb
ase is the secondary current maximum value when WCB / WCBd = 1.0, and WCBd is expressed as a design value of the counter balance. In this case, for the upstroke peak current, (IP / IPbase) =-0.941 (WCB / WCBD) +1.94 --- (1) For the downstroke peak current, (IP / IPbase) = 0.954 (WCB / WCBD) -0.965 A regression linear equation of (2) was obtained. By simultaneously solving the equations (1) and (2), the following equation (3) is obtained. (WCB / WCBD) = 1.533 (3) That is, WCB / WCBd = 1.533, that is, the most appropriate counterbalance weight is 1.533 times the design value =
It can be determined as 3,183 Kg. Regarding the regression analysis for deriving the above regression linear equations (1) and (2), the regression parameters a and b (the 0.94
1, 1.94, or 0.954, 0.965) will not be described in detail since it is in the field of well-known statistical mathematics. Similarly, the calculation procedure is omitted for the simultaneous equations of the regression linear equations (1) and (2).

Next, the operation of estimating the counter balance will be described along the processing procedure with reference to the flowchart shown in FIG. Note that the flowchart shown in FIG.
2 shows the processing operations of the first embodiment and the second embodiment, and the processing of S102 to S116 in the test mode 1 is a part related to the first embodiment. First, when the optimum counter balance weight calculation program loaded in the optimum counter balance calculator 53 is started by the signal input of the constant device 57 (S100), the contact COS / C1 of the control changeover switch 64 sets the speed of the test test operation. It is checked whether the setting has been switched to the setting device 63 (S10).
1). If the test mode has been switched, it is determined whether the test mode is a method based on the regression linear equation in mode 1 or a method based on the pump load estimation in mode 2.
In the case of the test mode 2, the process proceeds to S117 (S1
02). If the determination in S102 is the test mode 1, the method based on the regression linear equation is selected (S103), the first counterbalance weight WCB (or the turning radius Lc) is set, and a test operation is performed (S104). The state of the down-stroke and up-stroke detection switching relay DET61 is checked, and when the relay DET / C1 is "ON" (S105), the secondary current instantaneous value I _{2 D} (t) of the motor during the down-stroke operation. Is started, and M
The data of EMO1 is transferred to the maximum value calculator PCAL43, and the secondary current maximum value I of the motor at the time of down stroke is obtained.
_{2 DP} (t) is arithmetically detected and stored in the memory table MT45 (S106). It is determined whether the calculation of the secondary current maximum value has been completed n times (S107). If the calculation has been completed, the average value calculator MCA based on the data in the memory table 45 is determined.
The average value I _{2 DM} is calculated in L49 (S108).
If the relay DET / C1 is "OFF" and the DET / C2 is "ON" in the judgment of S105, the secondary current instantaneous value I _{2 U} (t) at the time of the upstroke is taken in, and its ME
MO2 data is transferred to the maximum value calculator PCAL44, and the secondary current maximum value I _{2 UP} during the up stroke
(T) is detected and stored in the memory table 46 (S109). It is determined whether the maximum value calculation has been completed n times (S110).
The average value calculator MCAL50 calculates the average value I based on the data
_{2 UM} is calculated (S111). With this, the average values I _{2 DM} and I _{2 UM} during the down stroke and the up stroke are obtained.
Is determined (S112).
If it has been completed, subsequently, the setting of the counterbalance weight is changed (for example, from 100% to 140%), and the pump jack is restarted (S113). Similarly, the secondary current maximum value and average value calculation and storage processing of S105 to S112 are performed for the changed counterbalance weight, and whether all calculations and storage are completed for the prescribed (for example, 5 types) counterbalance weight. Is determined (S114).

Next, S108 and S111 are executed by the counter balance calculation software of the optimum counter balance calculator 53.
The regression linear equations (1) and (2) are obtained from the relationship between the counterbalance WCB and the maximum secondary current as shown in FIG.
5). Finally, a simultaneous solution of the regression linear equations (1) and (2) yields, for example, WCB / WCBD = 1.533,
And the design value of the counterbalance weight is 2076
In the case of Kg, the optimal counterbalance weight is obtained as 2076 × 1.533 = 3.183 Kg. As described above, according to the first embodiment, the test operation is performed by operating the pump jack for a plurality of cycles or more as a test operation.
Detects and stores the secondary current instantaneous values of downstroke and upstroke, compares and averages the maximum values of those values, detects and displays the suitability or unsuitability of counter balance, and regresses from these stored values. Estimation of the optimal counterbalance is performed by deriving the linear equation, so that it is possible to calibrate the counterbalance weight in accordance with the actual operating conditions in the form of a test run before actual operation, enabling accurate and quick estimation of the counterbalance. Become.

Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 7 is a diagram showing characteristics of a torque coefficient and a crank angle in the counterbalance adjustment of the pump jack according to the second embodiment of the present invention. FIG. 8 is a diagram showing the relationship between the sucker rod load and the electric motor secondary current during the counter balance adjustment shown in FIG. Note that the flowcharts of FIGS. 1, 2, 5, and 6 are common to the first embodiment and are used in the second embodiment. 1 and 2 will be omitted. As is well known, a police rod load is converted to a crankshaft by a torque coefficient determined by a pump jack mechanism. FIG.
Fig. 7 shows an example of characteristics of a torque factor (torque coefficient) and a crank angle in a pump unit of API C456-304-120. When the crank angle is plotted on the horizontal axis and the torque coefficient is plotted on the vertical axis as shown in the figure, the torque coefficient for conversion to the crankshaft is simply the sine function value of the crank angle due to the characteristics of the link mechanism of the pump jack. is not. However, since there is a basic function for converting the rotational motion of the crankshaft into the reciprocating motion required for the operation of the down-hole pump, the characteristic of the torque coefficient with respect to the crank angle is almost symmetric about a certain angle of the crank. It is expected to be. In fact, the torque coefficient of this example is substantially symmetric about the axis of 180 deg. For example, the maximum torque coefficient occurs at the 75 deg point of the upstroke, and at the downstroke,
The maximum torque coefficient is obtained at (180−75) + 180 = 285 deg. In the present embodiment, focusing on this characteristic, the optimum counterbalance weight is estimated by the following method.

Next, a method of estimating the optimal counter balance will be described. Assuming that the design value of the maximum sucker rod torque at the time of upstroke is known, the net gearbox torque can be expressed by the following equations.

(Equation 1) Where: W _PRM : maximum polyside rod load
(Lbs) K _PJ : Torque coefficient that gives maximum sucker rod torque at upstroke (in) T _CB : Corresponding counterbalance torque (in-lbs) W _P : Pump load (lbs) T _LU : Upstroke -Net net box torque
(in-lbs) T _LD : Net torque of downstroke
(in-lbs)

Now, assuming that TCB giving T _LU = T _LD is determined as the optimal counterbalance torque (= TCBS), from equations (4) and (5), T _CBS = K _PJ (W _PRM −W _P / 2)---(6) Further, the following equation (7) is obtained from the equations (4) + (5). W _P · K _PJ = T _P = T _LU + T _LD --- (7) where: T _P : pump load torque (in-lbs) From this, the maximum net gearbox torque during upstroke is calculated. According to the secondary current peak value, and the point at which the secondary current peak value is generated and the net gearbox torque at the time of downstroke with the crank angle of 180 degrees as the axis of symmetry, the mode of the point of symmetry is calculated. If it can be detected by the secondary current value, the pump load torque can be known from the equation ( _7PR ). Here, since K _PJ and W _PRM are known as design values, the optimal counter balance torque can be calculated by equation (6).

The second embodiment is based on the above-described estimation calculation method. Hereinafter, when a specific example of the second embodiment is shown, it is assumed that the design value of the maximum police rod torque is 1.59 (pu) by the unit method. In addition, the counterbalance torque (=
Assume that the set value of T _CB ) is given by 1.1 (pu). By the test operation, the motor secondary current peak value at the time of the upstroke and the time, the motor at the time of the downstroke which is symmetrical to the peak current value generation time and the upstroke end point. The secondary current value is detected. This value was converted to the unit method, and T _LU = 0.490 (p.
u. ), Assuming _{T L D = -0.129 (p.u.} ), From (7), T _P = 0.490-0.129 =
0.361 From the equation (6), T _CBS = 1.59− (0.361 /
2) = 1.409 Therefore, T _CBS (pu) = 1.1 × 1.409 = 1.55
(Pu) and the optimum counter balance weight can be estimated.

Next, the above counter balance estimation is performed as shown in FIG.
The actual processing procedure will be described with reference to the flowchart shown in FIG. First, when the optimum counter balance weight calculation program of the "method by pump load estimation" in test mode 2 loaded into the optimum counter balance calculator 53 is started by a signal input from the constant unit 57 (S100), control is performed. Is the contact of the changeover switch 64 switched to the speed setting unit 63 side of the test test run?
Is checked (S101). Then the test mode is 1
It is determined whether or not the test mode 2 is satisfied, and in the case of the “method based on pump load estimation” in the test mode 2, the process proceeds to S117. Test mode 2
By the method based on the pump load estimation (S117),
(S118), an arbitrary counter balance weight is set and a test operation is performed 8S119). DET / C1 is ON, that is, instantaneous 2:00 current value detection during downstroke ?, O
Is the secondary current instantaneous value detected during the up stroke during FF?
(S120), and if OFF, the data of the MEMO 42 is transferred, and the optimum counter balance calculator 53 detects and stores the time at that point in time from the peak value of the motor secondary current during the upstroke and the elapsed signal 48. Do (S
121). Subsequently, the downstroke time with the upstroke end as the axis of symmetry is calculated as shown in FIG. 7 from the time when the secondary current has reached the maximum value and the upstroke end time (S122). Also, D is determined in S120.
When ET / C1 is "ON", that is, when the instantaneous value is detected at the time of the downstroke, the data of the MEMO 41 is transferred and the maximum secondary current at the time of the downstroke and the time are stored (S123). 2 of the downstroke corresponding to the target downstroke time calculated in S122
The next current value is detected and stored (S124). The secondary current maximum value of the up stroke and the 2
T _LU from the following current, obtains a T _LD, estimates the pump load torque T _P (7) below (S125). Estimated pump load torque T _P and the maximum Porisshi de lot torque W
By the design values or the like of _{PR M} (6) formula to calculate the optimum counterbalance weight (S126). The optimal counterbalance estimating calculation of the two methods described above is performed in the test mode 1 in the first method in FIGS.
The second method is referred to as "method based on pump load estimation" in test mode 2 and its processing procedure is shown. Here, the selection of test mode 1 and test mode 2 is based on the configuration shown in FIG.
Although not shown, it is considered that switching is performed by manual input.

Next, in the present invention, the pump jack speed at the time of estimating and calculating the optimum value of the counter balance is
The reason why the speed setter 63 sets a speed lower than the rated stroke speed will be described. FIG. 8 shows a 25%
The sucker rod torque and the motor secondary current at the starting speed were obtained by computer simulation. Compared to the case of the 100% stroke speed in FIG. 3, the pulsation of the sucker rod load and the pulsation of the motor secondary current based on the dynamic characteristics of the sucker rod system are clearly reduced. In other words, by reducing the stroke speed of the pump jack, it is possible to eliminate the problem of erroneous peak value detection that may be caused by the pulsation of the secondary current. The speed setting device 63 is provided for this purpose. As described above, in the counter balance adjustment system of the present invention, two methods can be set. As described above, the “method by the regression linear equation” involves the operation of changing the counter balance setting. Calculates and estimates the optimum value under the actual operating condition, so it affects the difference between the design value and the actual value of the sucker rod load or pump load compared to the conventional method of determining the counter balance from the design calculation value. Since it is not performed, there is a feature that accurate estimation can be performed. On the other hand, the "method based on pump load estimation" has a disadvantage that a design value of the maximum sucker rod torque at the time of uploading is required, but has an advantage that it does not require the work of changing the counter balance setting. Of course, the second method cannot always determine an accurate counterbalance optimum value in terms of using the design value of the maximum sucker rod torque. In other words, the "method based on pump load estimation" is optimal if it is adopted as a simple determination method for determining the optimum value of the counterbalance. Further, in the present invention, in order to reduce the load on the software processing of the controller, the software software for the above-described optimal counter balance calculation can be activated only when the changeover switch 64 is switched to the test side. Therefore, whether the normal counter balance is appropriate or not, as described above,
It is considered that the output of the comparator 51 is monitored by the monitor 52. That is, when the counter balance abnormality is frequently displayed on this monitor, the changeover switch 64 is switched to the test side to start the program for determining the optimum value of the counter balance, and the pump jack is always set to the optimum counter balance weight. It is possible to drive in the state. Conventionally, when the counter balance is not properly adjusted, the maximum load of the motor at the time of the upstroke and at the time of the downstroke greatly differ from each other. Is selected in consideration of the reduction of load capacity by the counterbalance, it is obviously placed in an overload state, and if the operation is continued in this overload state, the motor will eventually burn out, Or, it causes a serious failure of the drive mechanism including the reduction gear.
However, conversely, if a motor or a reduction gear is selected in consideration of the maximum unbalance load, the driving capacity is increased accordingly. The appropriate value of the counterbalance is generally determined by considering the design value.Therefore, there is a difference between the design value and the actual value, and the operating condition may be changed after the equipment is operated. In many cases, these problems are not sufficient, and if the counter balance adjustment system of the present invention is employed to adjust the counter balance, these problems can be solved and the peak torque applied to the drive system can be reduced. The difference between the maximum torque applied to the motor when the adjustment of the counter balance is optimal and when it is not is, for example,
As is apparent from the example of FIG. 4, the motor secondary current peak ratio in the optimum counterbalance state, that is, according to the present invention, the required maximum torque can be reduced to 50%. . As described above, the adjustment target of the counter balance has been described as the weight adjustment. However, the adjustment target may be, of course, the radius of the counter balance.

[0025]

As described above, according to the first aspect of the present invention, in setting different known counter balances, the pump jack is operated for a plurality of cycles n or more, and the maximum secondary current instantaneous value and the counter balance are set. From the data, a regression linear equation for estimating the change in the counterbalance with respect to the change in the secondary current maximum value during the upstroke and a regression linear equation for estimating the change in the counterbalance for the change in the secondary current maximum value during the downstroke are obtained. The optimal counterbalance value is determined from the intersection of the two straight lines, so that the optimal value of the counterbalance can be accurately determined under the actual use conditions without the need for detailed sucker rod load data. There is an effect that the required peak torque of the electric motor can be reduced by reducing the applied peak torque. According to the second invention, the value of the gearbox torque at the time of the maximum upstroke operation is set as a known value. Data on the maximum value of the instantaneous secondary current value and the time at which the maximum value is reached are obtained. From this data, the secondary current instantaneous value at the time of the downstroke with the upstroke end as the axis of symmetry is read, and the algebraic sum of the two values is read. , The pump load is estimated, and half of the estimated value is subtracted from the maximum gearbox torque to obtain the optimum counterbalance value. Therefore, a simple procedure that does not require changing the weight or radius of the counterbalance. This makes it possible to quickly determine the optimal counter balance,
There is an effect that the peak torque applied to the drive system can be reduced to reduce the required maximum torque of the electric motor.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a pump jack counterbalance adjusting device to which a vector control inverter of an induction motor according to a first embodiment of the present invention is applied.

FIG. 2 is a control block diagram of the counter balance adjusting device shown in FIG.

FIG. 3 is an explanatory diagram showing a relationship between a sucker rod load and a secondary current of a motor by computer simulation of the pump jack shown in FIG. 1;

FIG. 4 is an explanatory diagram of a regression linear equation calculated by an optimum counter balance calculator shown in FIG. 2;

FIG. 5 is a part of a flowchart of an optimum counter balance weight calculation shown in FIG. 4;

FIG. 6 is a part of a flowchart of an optimum counter balance weight calculation shown in FIG. 4;

FIG. 7 is a diagram showing characteristics of a torque coefficient and a crank angle in counterbalance adjustment of a pump jack according to a second embodiment of the present invention.

8 is a diagram showing the relationship between the sucker rod load and the motor secondary current at the time of the counter balance adjustment shown in FIG. 7;

FIG. 9 is a characteristic diagram of a rod load of a conventional pump jack.

FIG. 10 is a characteristic diagram of a rod load at a speed of 200% of the pump jack shown in FIG. 9;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pump motor for motor drive 2 Speed detector 3 Inverter control part 4 Counter balance adjustment device 31 Linear commander 32 Speed adjuster 33 Current adjuster 34 PWM controller 41 MEMO1 42 MEMO2 43,44 Secondary current maximum value calculator 45 , 46 memory table 47 timing pulse generator 48 elapsed time signal generator 49, 50 average value calculator 51, 56 comparator 52, 54 display 53 optimal counter balance calculator 55 stroke time calculator 57 constant unit 58 reference point signal generator 59 changeover switch 60 sequence storage memory 61 detection changeover relay 62, 63 speed setting device 64 control changeover switch

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshio Miyano 2-1 Kurosaki Castle Stone, Yawatanishi-ku, Kitakyushu-city, Fukuoka Prefecture Inside Yaskawa Electric Co., Ltd. (72) Inventor Richard El Prat Inventor Richard El Prat 45240 Cincinnati Kemper Springs Drive, Ohio United States 11895, Inside Electric Motor Systems, Inc. (72) Inventor Brian McKinnon T-2, Alberta, Canada Sea 3 Sea 6 Calgary 76 Avenue Southeast 5115, F-term in Warmac Electric Limited 5H576 AA05 BB02 DD04 EE01 EE11 GG04 JJ03 JJ17 LL07 LL22 5H607 AA04 BB01 BB0 6 CC01 CC05 CC07 EE38 FF06 HH03

Claims (8)

[Claims] 1. A speed control system using a variable voltage and variable frequency power supply.
Induction motor driven pump jack configured to be controlled
In the counter balance adjustment method of the above, the pump
Operate the jack for at least n cycles (n ≧ 1)
Electric drive for each of stroke and downstroke
Means for detecting and storing the maximum value of the instantaneous secondary current of the machine, n
The average for the n maximum values obtained by cycle operation
Average (I_{U 1} , I_{D 1} Means), and the pump
Change the weight or radius of the jack counterbalance
Operation for at least n cycles, and
Upstroke and downstroke under counterbalance
The average value (I) of the maximum values of the n secondary currents during the stroke_{U 2} ,
I_{D Two} ) Is provided, and two
Average value of the maximum value of the next current (I _{U 1} , I_{U 2} )
Upstroke secondary current maximum value and counterbalance weight
Calculate the regression line equation for the change of the amount or radius, and
On the other hand, the average value of the maximum secondary current during downstroke
(I_{D 1} , I_{D 2} ) By the downstroke secondary current
Maximum and counter balance for weight or radius changes
Regression line equation
Special counterbalance weight or radius.
Adjustment method of pump jack counter balance. 2. A pump jack count according to claim 1.
In the balance adjustment method, adjust the weight or radius of the pump jack counterbalance.
Change m or more times (m ≧ 2), and operate
The maximum value of the secondary current during upstroke.
Average value (I_{U 1} , I_{U 2} , I_{U 3} , ..., I_{U m} By)
Therefore, the maximum secondary current of the upstroke and the counter
Find the regression line equation for the change in weight or radius of the
On the other hand, the maximum value of the secondary current during downstroke
Average (I _{D 1} , I_{D 2} , I_{D 3} , ..., I_{D m} By)
Downstroke secondary current maximum value and counter balance
Find the regression linear equation for changes in weight or radius,
The optimal counter balance is determined by the intersection of both straight lines
Counterbalance balun for pump jack
Adjustment method. 3. The pump jack counter balance adjusting method according to claim 1, wherein at least one stroke of the pump jack causes at least one cycle of operation to perform upstroke and downstroke operation. Means for sampling and detecting the instantaneous value of the secondary current with respect to time, storing the detected current value and the corresponding sampling time as a pair in a table, means for detecting the upstroke end time, and the value of the table Means for detecting the secondary current maximum value (I _UP ) during the upstroke and its time (hereinafter referred to as the secondary current maximum value time) from the table. It takes the maximum value time from the up stroke of the secondary current - Kuendu up time equal to the elapsed time of the down stroke of the - secondary current instantaneous value of the click time means for detecting (I _DX) Only, pumps estimates the pump load torque by the algebraic sum of the current values (I _UP + I _DX), and estimates a value obtained by subtracting the maximum policy de rod torque the 1/2 as the best counterbalance torque Jack counter balance adjustment method. 4. The method according to claim 1, wherein a difference between respective average values of the maximum values of the secondary currents during the up stroke and the down stroke is calculated. A method for adjusting the counterbalance of a pump jack, comprising determining whether or not the counterbalance is appropriate based on the result and activating a program for determining an optimum value of the counterbalance. 5. The method for adjusting the counterbalance of a pump jack according to any one of claims 1 to 4, wherein the estimation calculation for determining the optimum value of the counterbalance is performed.
A pump jack counter balance adjusting method, wherein a control switch is switched to a test side to set a pump jack speed to a speed lower than a rated stroke speed. 6. The method according to claim 1, wherein the program for determining the optimum value of the counterbalance is a test mode using a method based on a regression linear equation and a method based on pump load estimation. And a pump jack counter balance adjustment method. 7. A pump jack counter balance adjusting device for adjusting a counter balance for reducing a drive capacity of a pump jack drive system in which an induction motor for driving a pump jack is speed-controlled by an inverter of a variable voltage and a variable frequency power supply. A program starting means for starting a program for determining an optimum value of the counter balance by an input signal from the constant device;
A test speed setting means for setting the speed lower than the rated stroke speed by switching the control switch upon activation of the counter balance optimum value determination program, and a method based on a regression linear equation of the counter balance optimum value determination program by selecting a test mode. , A counter balance setting means for setting and changing the counter balance weight or radius, and a drive motor for each of an up stroke and a down stroke based on the set and changed counter balance. Means for detecting and storing the maximum value of the instantaneous current instantaneous value, average value detecting means for calculating each average value for the maximum value, and a counter for calculating the difference between the average values to determine whether or not the counterbalance is appropriate. Balance determination means, and secondary during the upstroke. The regression linear equation for the maximum value of the up-stroke secondary current and the change in the counter balance is obtained from the average value of the maximum value of the flow, and the maximum value of the down-stroke secondary current and the counter are calculated by the average value of the maximum value of the secondary current during the down stroke. A counterbalance adjusting device for a pump jack, comprising an optimum counterbalance calculating means for calculating a regression linear equation for a change in balance and determining an optimum counterbalance weight or radius based on an intersection of both straight lines. 8. A pump jack count according to claim 7.
In the balance adjustment device, the optimum value of the counter balance is determined by selecting the test mode.
Test to select a method by estimating the pump load of the program
Mode selection means, upstroke and downstroke
Instantaneous value of secondary current for each stroke time during
Of the detected current value and the corresponding sample
Storage means for storing pulling times in pairs in a table
And stroke to detect the up stroke end time
End time detection means and
The secondary current maximum value (I_{U P}) And the time
Means for detecting the output time and an upstroke from the table.
From the maximum secondary current time during
Downstroke with elapsed time equal to the time to finish
Instantaneous secondary current of time (I_DX ) Means to detect
The pump load torque is estimated by the algebraic sum of the current values,
One half of the pump load torque is
The value subtracted from the torque is the optimal counterbalance torque.
Having an optimal counter balance calculating means for estimating
Counterbalance adjustment device for pump jack
Place.