Device and method for accurately locating motor parameters at top and bottom dead points of beam pumping units

Abstract

The present invention relates to the field of oil pumping units, and in particular to a device and method for accurately locating the motor parameters at the top and bottom dead centers of a beam pumping unit. The device comprises a three-phase electrical parameter acquisition module for acquiring the motor input power of the oil pumping unit, a speed monitoring device for acquiring the real-time speed of the motor, and a crank fixed-point trigger and a calculation module for acquiring the speed of the donkey head suspension point. The speed monitoring device and the crank fixed-point trigger are both electrically connected to the three-phase electrical parameter acquisition module, which is in turn electrically connected to the calculation module. The electrical parameters acquired through the three-phase electrical parameter acquisition module, the speed monitoring device, and the crank fixed-point trigger are relatively stable and less prone to error. The device utilizes a top and bottom dead center search algorithm to automatically locate the exact positions of the top and bottom dead centers, thus resolving the difficulty of installing the crank fixed-point trigger.

Description

Technical Field

[0001] The invention relates to the field of oil pumping unit devices, in particular to a device and method for accurately positioning motor parameters at upper and lower dead points of a beam pumping unit. Background Art

[0002] The dynamometer diagram is crucial first-hand data for the production process of a pumping unit. It is a closed curve with the suspension point displacement as the horizontal axis and the suspension point load as the vertical axis during the stroke cycle. It contains a wealth of useful information about the oil well. The dynamometer diagram can be used to determine the well's operating conditions, including dozens of conditions such as pump sticking, insufficient fluid supply, sucker rod breakage, valve leakage, gas impact, barrel derailment, and wax deposition. It can also analyze parameters such as stroke loss, pumping unit load utilization, well fluid production, water content, and dynamic liquid level.

[0003] There are two main methods for obtaining the dynamometer diagram of a pumping unit. One is a direct method, which typically uses a displacement or angle sensor to obtain the displacement of the polished rod, and a load sensor to obtain the load on the suspension rope, and then the displacement and load are mapped one to one. The other is an indirect method, which uses the electrical parameters of the motor, such as power, speed, torque, and other parameters, combined with the physical model of the pumping unit to calculate the displacement and load of the polished rod of the pumping unit.

[0004] Compared with the direct method, the indirect method has the advantages of easy installation, low cost, and convenient maintenance, but at the same time its calculation difficulty is also increased. One of the difficulties is that since the indicator diagram reflects the changes in the cycle of the bare rod from bottom dead center to top dead center and then back to bottom dead center, it is necessary to divide the electrical parameters into a periodic sequence according to the pumping unit stroke frequency and be able to give the accurate position of the upper and lower dead centers in the cycle. The current common practice is to install the crank fixed point trigger at the bottom dead center position. Generally, workers visually inspect the bottom dead center position and then install the crank fixed point trigger. This method will lead to inaccurate bottom dead center position. In addition, in actual operation, it is more practical to install the crank fixed point trigger at the crank position corresponding to the top dead center. Therefore, a method is needed to simplify the installation of the crank fixed point trigger so that the crank fixed point trigger can accurately locate the electrical parameters corresponding to the upper and lower dead centers when installed in any position. Summary of the Invention

[0005] The purpose of the present invention is to provide a device and method for accurately locating the motor parameters of the top and bottom dead points of a beam pumping unit.

[0006] The technical solutions of the present invention are as follows:

[0007] A device for accurately determining the motor parameters of the upper and lower dead points of a beam pumping unit, comprising a three-phase electrical parameter acquisition module for acquiring the motor parameters of the pumping unit, a speed monitoring device for acquiring the real-time speed of the motor of the pumping unit, and a crank fixed point trigger and a calculation module for acquiring the donkey head suspension point: the speed monitoring device and the crank fixed point trigger are both electrically connected to the three-phase electrical parameter acquisition module, and the three-phase electrical parameter acquisition module is electrically connected to the calculation module.

[0008] The rotation speed monitoring device is a rotation speed sensor or a rotation speed estimator.

[0009] The computing module is an edge computing module that establishes a connection with the oil well database through a gateway device.

[0010] The edge computing module is also connected to the host computer through a gateway device.

[0011] The three-phase electrical parameter acquisition module is installed at the motor input end of the oil pumping unit.

[0012] The crank fixed point trigger consists of a magnet, a proximity switch, and a transmission module. The magnet is attached to the crankshaft of the pumping unit. Its rotational trajectory passes through the sensing surface of the proximity switch. The proximity switch collects the bottom dead center position signal and sends it to the edge computing module via the transmission module.

[0013] A method for accurately locating the motor parameters of the upper and lower dead points of a beam pumping unit comprises the following steps: Step 1: a motor speed sensor collects the real-time motor speed of the pumping unit; Step 2: a crank fixed point trigger collects the fixed point position in one stroke of the pumping unit; Step 3: the motor speed sensor sends the real-time motor speed and the crank fixed point trigger sends the fixed point position to a three-phase electrical parameter collection module; Step 4: the three-phase electrical parameter collection module collects electrical parameter data of the motor input end of the pumping unit within each sampling time interval, and each piece of electrical parameter data includes the A-phase current I A , B phase current I B , C phase current I C , A phase voltage U A , B phase voltage U B , C phase voltage U C , motor active power P, motor speed N; the three-phase electrical parameter acquisition module sends the electrical parameter data of the motor input end to the edge computing module; Step 5: Manually input the pumping unit data or obtain the pumping unit data from the database; Step 6: Calculate the motor torque based on the motor active power and motor speed obtained in Step 4; Step 7: Based on the physical model for calculating the upper and lower dead point motor parameters, calculate the motor parameters of the bottom dead center and top dead center through multiple motor torques and fixed point positions.

[0014] The physical model for calculating the parameters of the upper and lower dead points of the motor includes the following steps: Step a: Since the motor torque at other times except at the upper and lower dead points is related to the suspension load; since the suspension load changes in each cycle, the change of the motor torque in the time sequence can be analyzed, and the position of the upper dead point or the lower dead point when the change is the smallest; the A phase current I in each sampling time interval is calculated. A , B phase current I B , C phase current I C , A phase voltage U A , B phase voltage U B , C phase voltage U C , motor active power P, motor speed N, according to the torque formula M m =9550P / N, the motor torque M can be calculated from the motor active power, speed and motor efficiency. m , split it according to the trigger point of the crank fixed point trigger, and assume that the split motor torque data is:

[0015]

[0016]

[0017] …

[0018]

[0019] Among them, M m Represents the motor torque, q represents the number of sampling points in a cycle, and p represents the number of samples participating in the training. Now estimate the position of the bottom dead point in a cycle sequence (1 to q), and set the sampling position of the bottom dead point at {id b ∈Z|s≤id b ≤t}; where Z represents the integer domain. Under the assumption that the crank moves at a constant speed, the position of the top dead center is offset backward from the bottom dead center. The formula for calculating the top dead center is 1: Δu=q·(θ t -θ b ) / (2π). Among them, θ t Indicates the crank angle corresponding to the time when the pumping unit reaches the top dead center; θ b Indicates the crank angle corresponding to when the pumping unit head reaches the bottom dead center;

[0020] Step b: Since the change of the motor torque at the upper and lower dead points is the smallest, it can be seen that the variance of the motor torque at the upper and lower dead points is the smallest; using the variance formula: in Formula 2 can be listed:

[0021]

[0022] st s≤j≤t, j∈Z

[0023] Solve formula 2 to get the bottom dead center number id b ; Get the motor torque corresponding to the bottom dead point in each cycle, and at the same time get the A-phase current I corresponding to the bottom dead point in each cycle A , B phase current I B , C phase current I C , A phase voltage U A , B phase voltage U B , C phase voltage U C .

[0024] Step c: Re-divide the motor torque data according to the bottom dead center sequence number obtained in step b, so that the starting value is the torque of the motor at the bottom dead center; after re-division, the motor torque sequence corresponding to the bottom dead center in the new cycle sequence is numbered 1; the torque sequence corresponding to the top dead center is numbered 1+Δu.

[0025] The beneficial effects of the present invention are: the present invention obtains electrical parameters through an electrical parameter acquisition module, a speed sensor, a crank fixed point trigger and an edge computing module, and the electrical parameter data is relatively stable and not prone to errors; the upper and lower dead point search algorithms are used to automatically find the positions of the upper and lower dead points, solving the problem of difficult installation of the crank fixed point trigger. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The foregoing and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.

[0027] in: Figure 1 This is a schematic diagram of the oil pumping unit model of the present invention;

[0028] Figure 2 This is a schematic diagram of the structural principle of the present invention;

[0029] Figure 3 It is a schematic diagram of the process of the present invention;

[0030] 1 is the three-phase electrical parameter acquisition module, 2 is the host computer, 3 is the edge computing module, 4 is the speed monitoring device, and 5 is the crank fixed point trigger. DETAILED DESCRIPTION

[0031] See also Figure 1 As shown, a device for accurately determining the motor parameters of the upper and lower dead points of a walking beam pumping unit includes a three-phase electrical parameter acquisition module 1 for acquiring the motor parameters of the pumping unit, a speed monitoring device 4 for acquiring the real-time speed of the motor of the pumping unit, and a crank fixed point trigger 5 and a calculation module for acquiring the donkey head suspension point: the speed monitoring device and the crank fixed point trigger are both electrically connected to the three-phase electrical parameter acquisition module, and the three-phase electrical parameter acquisition module is electrically connected to the calculation module.

[0032] The speed monitoring device is a motor speed sensor or speed estimator. The speed sensor is installed near the motor shaft to collect motor speed information. Typically, it is a Hall proximity switch speed sensor, which consists of two parts: a magnet and a proximity switch. The magnet is adsorbed on the motor shaft, and the proximity switch is in a fixed position. When the magnet rotates one circle with the shaft, it triggers the proximity switch once. The time difference between the two triggering of the proximity switch is the motor rotation period. The proximity switch is electrically connected to the computing module and transmits the trigger signal to the computing module for processing. The speed estimator is a software module, generally built into the inverter.

[0033] The computing module is an edge computing module 3 that establishes a connection with the oil well database through a gateway device.

[0034] The edge computing module is also connected to the host computer 2 through a gateway device.

[0035] The three-phase electrical parameter acquisition module is installed at the motor input end of the oil pumping unit.

[0036] The crank fixed point trigger consists of a magnet, a proximity switch, and a transmission module. The magnet is attached to the crankshaft of the pumping unit. Its rotational trajectory passes through the sensing surface of the proximity switch. The proximity switch collects the bottom dead center position signal and sends it to the edge computing module via the transmission module.

[0037] A method for accurately locating the motor parameters of the upper and lower dead points of a beam pumping unit comprises the following steps: Step 1: a motor speed sensor collects the real-time motor speed of the pumping unit; Step 2: a crank fixed point trigger collects the fixed point position in one stroke of the pumping unit; Step 3: the motor speed sensor sends the real-time motor speed and the crank fixed point trigger sends the fixed point position to a three-phase electrical parameter collection module; Step 4: the three-phase electrical parameter collection module collects electrical parameter data of the motor input end of the pumping unit within each sampling time interval, and each piece of electrical parameter data includes the A-phase current I A , B phase current I B , C phase current I C , A phase voltage U A , B phase voltage U B , C phase voltage U C , motor active power P, motor speed N; the three-phase electrical parameter acquisition module sends the electrical parameter data of the motor input end to the edge computing module; Step 5: Manually input the pumping unit data or obtain the pumping unit data from the database; Step 6: Calculate the motor torque based on the motor active power and motor speed obtained in Step 4; Step 7: Based on the physical model for calculating the upper and lower dead point motor parameters, calculate the motor parameters of the bottom dead center and top dead center through multiple motor torques and fixed point positions.

[0038] According to the crankshaft torque formula 1:

[0039] Where M is the crankshaft torque, W is the polished rod load, B is the unbalance value of the pumping unit itself, c is the distance from the walking beam balance weight to the walking beam support center, a is the length of the walking beam forearm, and W b is the weight of the balance block at the tail of the walking beam, is the torque factor, M cmax is the maximum crank balance torque, τ is the crank balance phase angle;

[0040] because is a function of θ, which is defined as Equation 2: Where Δθ is the change in crank angle, ΔS is the change in suspension point position, and v r is the linear velocity of the suspension point, ω c is the crank angular velocity; since the suspension point linear velocity is 0 at the top dead center or bottom dead center, the torque factor corresponding to the top and bottom dead centers is equal to zero, which gives Formula 3:

[0041]

[0042] Among them, θ t Indicates the angle of the crank when the donkey head is at the top dead center. This value is a fixed value for a fixed walking beam pumping unit; θ b It indicates the angle of the crank at the bottom dead center. This value is fixed for a fixed walking beam pumping unit.

[0043] Substituting Equation 2 into Equation 1 yields Equation 4 at bottom dead center:

[0044] M t +M cmax sin(θ t +τ)=0,

[0045] And at the top dead center, Formula 5: M b +M cmax sin(θ b +τ)=0

[0046] The crankshaft torque is obtained by the motor torque passing through the transmission mechanism, that is, Formula 6:

[0047] M=η m ·r·(M m -M m0 ), where η m is the motor efficiency, which can be obtained directly from the motor manufacturer, r is the transmission ratio, M m is the motor torque, M m0 is the motor idling torque;

[0048] Substituting Equation 6 into Equation 4 yields Equation 7:

[0049] Substituting Equation 6 into Equation 5 yields Equation 8:

[0050] Since η m ,τ,M m0 、M cmax They are all fixed values, so at the upper and lower dead points is fixed, while the motor torque M m M at other times except at the top and bottom dead centers m It is related to the suspension load W; since the suspension load changes in each cycle, it can be analyzed by M m The change of the motor torque in each sampling time interval is divided according to the trigger point of the crank fixed point trigger, and the divided motor torque data is set as:

[0051]

[0052]

[0053] …

[0054]

[0055] Among them, M m Represents the motor torque, q represents the number of sampling points in a cycle, and p represents a total of p cycles sampled; each sequence represents the motor torque value sampled from the moment the proximity switch is triggered to the next proximity switch trigger. The calculation formula for the motor torque value is M m =9550P / N, where P is the motor active power collected by the three-phase electrical parameter acquisition module, and N is the motor speed collected by the three-phase electrical parameter acquisition module; the crank fixed point trigger is triggered twice, corresponding to one crank rotation. Based on the positional relationship between the crank fixed point trigger installed on site and the bottom dead center, it is estimated that the sampling position of the bottom dead center is {id b ∈Z|s≤id b ≤t}; where Z represents an integer domain. Under the assumption that the crank moves at a constant speed, the position of the top dead center is offset backward from the bottom dead center. The formula for calculating the top dead center is 9: Δu=q·(θ t -θ b ) / (2π)

[0056] Since the change of the motor torque at the upper and lower dead points is the smallest, it can be seen that the variance of the motor torque at the upper and lower dead points is the smallest. Therefore, according to formula 8 and the variance formula commonly used in computer programming, such as:

[0057] in

[0058]

[0059] Formula 2 can be listed:

[0060]

[0061] st s≤j≤t, j∈Z

[0062] Since the value of j is a finite integer, the bottom dead center number id can be obtained by exhaustive method. b ; Get the motor torque corresponding to the bottom dead point in each cycle, and at the same time get the A-phase current I corresponding to the bottom dead point in each cycle A , B phase current I B , C phase current I C , A phase voltage U A , B phase voltage U B , C phase voltage U C The motor torque data can then be re-divided based on the bottom dead center number obtained in step b, so that the starting value is the motor torque at bottom dead center. After re-dividing, the motor torque number corresponding to bottom dead center is 1; the torque number corresponding to top dead center is 1 + Δu.

[0063] θ in Formula 9 b The solution formula is:

[0064]

[0065] θ t The solution formula is:

[0066]

[0067] Where R is the crank radius, P is the connecting rod length, A is the length of the front arm of the rocker beam, C is the length of the rear arm of the rocker beam, I is the horizontal distance between the rocker beam support center and the crank rotation center, h is the vertical distance between the rocker beam support center and the crank rotation center, K is the distance between the rocker beam support center and the crank rotation center, and S is the distance between the rocker beam support center and the connecting rod axis.

[0068] Example 1: Based on the stroke number N of the pumping unit s (The unit is "strokes per minute", its value is related to the crank speed N c , the unit is "circles per minute"), set the sampling interval to:

[0069]

[0070] The unit is seconds. Thus, 250 points are sampled for each stroke. Sampling begins when the crank fixed-point trigger is triggered, and a total of 40 cycles are sampled, resulting in a total of 10,000 points. At this point, q = 250, p = 40, then:

[0071]

[0072]

[0073] …

[0074]

[0075] Assume that after the crank passes the crank fixed point trigger, it rotates about 10 degrees to reach the bottom dead center. Since one sampling point corresponds to 360 / 250≈1.44 degrees, 10 degrees is about 7 points (10 / 1.44≈6.94). b ∈Z|4≤id b ≤10}, then we can choose {4, 5, 6, 7, 8, 9, 10}. Let the loss function be f(j):

[0076]

[0077] Calculate the values ​​of f(4), f(5), f(6), f(7), f(8), f(9), and f(10) respectively. The j corresponding to the minimum value is the serial number corresponding to the bottom dead center in each cycle: id b The corresponding serial number of the top dead center in each cycle is id b +Δu; According to the obtained serial numbers of the upper and lower dead points, the motor torque corresponding to the serial number of the lower dead point in each cycle can be obtained At the same time, the A-phase current corresponding to the bottom dead point in each cycle can also be obtained Phase B current Phase C current Phase A voltage Phase B voltage Phase C voltage Thus, by locating the upper and lower dead points, the motor parameters can be re-divided into cycles.

[0078] The above description is merely an embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A method for accurately locating the motor parameters of the top and bottom dead points of a beam pumping unit, comprising the following steps: Step 1: The motor speed sensor collects the real-time speed of the pumping unit's motor. Step 2: The crank fixed-point trigger collects the fixed-point position of the pumping unit during a stroke. Step 3: The motor speed sensor sends the real-time speed of the motor and the crank fixed-point trigger sends the fixed-point position to the three-phase electrical parameter acquisition module. Step 4: The three-phase electrical parameter acquisition module collects electrical parameter data from the pumping unit's motor input within each sampling time interval. Each piece of electrical parameter data includes A-phase current, B-phase current, C-phase current, A-phase voltage, B-phase voltage, C-phase voltage, motor active power, and motor speed. The three-phase electrical parameter acquisition module sends the electrical parameter data of the motor input end to the edge computing module; Step 5: Manually input the pumping unit data or obtain the pumping unit data from the database; Step 6: Calculate the motor torque based on the motor active power and motor speed obtained in Step 4; Step 7: Based on the physical model for calculating the upper and lower dead point motor parameters, calculate the motor parameters of the lower and upper dead points through multiple motor torques and fixed point positions; the physical model for calculating the upper and lower dead point motor parameters includes the following steps: Step a: Divide the A-phase current, B-phase current, C-phase current, A-phase voltage, B-phase voltage, C-phase voltage and motor torque in each sampling time interval into cycles. Let the divided motor torque data be: Among them, M m Represents the motor torque, q represents the number of sampling points in a cycle, and p represents the number of samples participating in the training; Now it is estimated that the bottom dead point is within the position of a cycle sequence 1 to q, and the sampling position of the bottom dead point is set at {id b ∈Z|s≤id b ≤t}; where Z represents the integer domain. Under the assumption that the crank moves at a constant speed, the position of the top dead center is offset backward from the bottom dead center. The formula for calculating the top dead center is 1: Δu=q·(θ t -θ b ) / (2π); where θ t Indicates the crank angle corresponding to the time when the pumping unit reaches the top dead center; θ b Indicates the crank angle corresponding to when the pumping unit head reaches the bottom dead center; Step b: Since the change of the motor torque at the upper and lower dead points is the smallest, it can be seen that the variance of the motor torque at the upper and lower dead points is the smallest; using the variance formula: in Formula 2 can be listed: Solve formula 2 to get the bottom dead center number id b ; Get the motor torque corresponding to the bottom dead point in each cycle, and at the same time get the A-phase current, B-phase current, C-phase current, A-phase voltage, B-phase voltage, and C-phase voltage corresponding to the bottom dead point in each cycle; Step c: Re-divide the motor torque data according to the bottom dead center sequence number obtained in step b; after re-division, the motor torque sequence number corresponding to the bottom dead center in the new cycle sequence is 1; the torque sequence number corresponding to the top dead center is 1+Δu.

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