Speed reduction control method, device and system for permanent magnet electric submersible plunger pump

Abstract

The invention discloses a permanent magnet electric submersible plunger pump speed reduction control method, device and system. The method comprises the steps that in the current operation period, when the angle of a motor rotor reaches the rotor angle corresponding to a preset deceleration point, the driving current frequency of a motor is reduced, so that a plunger of the permanent magnet electric submersible plunger pump is decelerated to reach the target limit position; wherein if the current operation cycle is the first operation cycle, the rotor angle corresponding to the deceleration point is determined based on the operation position of the plunger in the pump body and the self-learning result of the corresponding rotor angle; otherwise, determining the rotor angle corresponding to the deceleration point based on the rotor angle and the error angle corresponding to the deceleration point in the previous operation cycle. The rotor angle corresponding to the deceleration point can be accurately positioned, accurate control over the upper limit position and the lower limit position of the plunger pump is achieved, and the phenomena of top collision and bottom collision are effectively avoided or reduced in the operation process.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, and in particular to a deceleration control method, device and system for a permanent magnet electric submersible plunger pump. Background Art

[0002] In oil well mining, the permanent magnet electric submersible plunger pump is a high-efficiency fluid conveying equipment that combines a permanent magnet motor, an electric submersible structure and a plunger pump body. It achieves the suction of downhole fluid by converting the rotational motion of the permanent magnet synchronous motor into the reciprocating motion of the plunger pump body.

[0003] Under traditional control strategies, permanent magnet submersible piston pumps have some problems. 1) In the piston pump body, when the plunger moves to the upper and lower limit positions of the pump body, it will hit the top or bottom. Mechanical structural limitations prevent the motor from continuing to rotate, and the mechanical impact force is large, seriously affecting the service life of the permanent magnet submersible piston pump. 2) Frequent mechanical impact will accelerate the damage of components, making the permanent magnet submersible piston pump's operating failure rate increase, and maintenance costs will also increase.

[0004] To solve the above problems, the following measures can be taken:

[0005] 1) Installing springs at the upper and lower limit positions to buffer mechanical shock can extend the service life to a certain extent, but it cannot fundamentally avoid the impact at the limit positions;

[0006] 2) Detecting a sudden increase in current determines whether the plunger has reached the upper or lower limit positions of the pump body. Based on the detection results, the average time of the plunger's multiple strokes within the pump body is determined. This is used to estimate the moment when the plunger approaches the upper or lower limit positions, and to decelerate in advance at that moment. Alternatively, when a sudden increase in current is detected, the drive to the permanent magnet synchronous motor is disconnected to reduce mechanical shock. The stator current suddenly increases when the plunger reaches the upper or lower limit positions of the pump body because the plunger is restricted by the upper and lower limit positions of the pump body and cannot move. The rotor of the permanent magnet synchronous motor is forced to stop rotating, entering a locked state, resulting in a momentary increase in stator current. Summary of the Invention

[0007] When using the sudden increase in current to determine whether the plunger has reached the upper and lower limit positions of the pump body, the current fluctuation is complex and the response is not timely, resulting in errors in the judgment of whether the plunger has reached the upper and lower limit positions of the pump body. This in turn leads to inaccurate estimation of the moment when the plunger approaches the upper and lower limit positions, and it is impossible to decelerate more accurately in advance to avoid mechanical impact of the plunger pump at the upper and lower limit positions.

[0008] In view of the above problems, the present invention is proposed to provide a method, device and system for controlling deceleration of a permanent magnet electric submersible piston pump that overcomes the above problems or at least partially solves the above problems.

[0009] An embodiment of the present invention provides a deceleration control method for a permanent magnet electric submersible piston pump, comprising:

[0010] In the current operating cycle, when the angle of the motor rotor reaches the rotor angle corresponding to the preset deceleration point, the motor drive current frequency is reduced to decelerate the plunger of the permanent magnet submersible piston pump to reach the target limit position; wherein, if the current operating cycle is the first operating cycle, the rotor angle corresponding to the deceleration point is determined based on the self-learning results of the operating position of the plunger in the pump body and the corresponding rotor angle;

[0011] Otherwise, the rotor angle corresponding to the deceleration point is determined based on the rotor angle and error angle corresponding to the deceleration point in the previous operating cycle. The process of determining the error angle corresponding to the deceleration point in the previous operating cycle includes:

[0012] Determining a theoretical rotor angle corresponding to a preset calibration point, and determining a time interval required for the motor to run from a starting angle of a current operating cycle to the theoretical rotor angle; wherein if the previous operating cycle is the first operating cycle, the theoretical rotor angle corresponding to the calibration point is determined based on the self-learning result; otherwise, the calibration rotor angle corresponding to the calibration point in the operating cycle before the previous operating cycle is determined;

[0013] After the motor runs for the time interval from the starting angle, the stator voltage is increased to a preset amplitude within a preset time; based on the increased stator voltage and the corresponding current collected, as well as the electromagnetic characteristic parameters of the motor, a voltage equation is used to determine the correction rotor angle corresponding to the correction point; and the error angle is determined based on the theoretical rotor angle corresponding to the correction point and the correction rotor angle.

[0014] In some optional embodiments, the self-learning process of the plunger running in the pump body includes:

[0015] Start the permanent magnet submersible piston pump and monitor the changes in motor current in real time. By determining whether the current increase reaches a preset threshold, the moment when the plunger reaches the top and bottom of the pump body is identified, and the first motor rotor angle corresponding to the plunger reaching the top of the pump body and the second motor rotor angle corresponding to the plunger reaching the bottom of the pump body are recorded.

[0016] In some optional embodiments, determining the rotor angle corresponding to the deceleration point based on a self-learning result of the operating position of the plunger in the pump body and the corresponding rotor angle includes:

[0017] determining a difference between an angle of a rotor of the first motor and an angle of a rotor of the second motor;

[0018] Based on the difference and the distance between the top and bottom of the pump body, determining the running angle of the motor rotor corresponding to the unit distance of the plunger running in the pump body;

[0019] The rotor angle corresponding to the deceleration point is determined based on the distance between the deceleration point and the target limit position, the running angle of the motor rotor corresponding to the unit distance of the plunger running in the pump body, and the motor rotor angle corresponding to the plunger reaching the target limit position.

[0020] In some optional embodiments, determining the rotor angle corresponding to the deceleration point based on the distance between the deceleration point and the target limit position, the running angle of the motor rotor corresponding to the unit distance of the plunger running in the pump body, and the motor rotor angle corresponding to the plunger reaching the target limit position includes:

[0021] If the deceleration point is set at a preset distance from the top of the pump body, the rotor angle corresponding to the deceleration point is determined based on the distance between the deceleration point and the top of the pump body, the running angle of the motor rotor corresponding to the unit distance of the plunger running in the pump body, and the motor rotor angle corresponding to the plunger reaching the top of the pump body;

[0022] If the deceleration point is set at a preset distance from the bottom of the pump body, the rotor angle corresponding to the deceleration point is determined based on the distance between the deceleration point and the bottom of the pump body, the running angle of the motor rotor corresponding to the unit distance of the plunger running in the pump body, and the motor rotor angle corresponding to the plunger reaching the bottom of the pump body.

[0023] In some optional embodiments, if the previous operating cycle is the first operating cycle, the theoretical rotor angle corresponding to the correction point is determined based on the self-learning result, including:

[0024] determining a difference between an angle of a rotor of the first motor and an angle of a rotor of the second motor;

[0025] Based on the difference and the distance between the top and bottom of the pump body, determining the running angle of the motor rotor corresponding to the unit distance of the plunger running in the pump body;

[0026] The rotor angle corresponding to the calibration point is determined based on the distance between the calibration point and the target limit position, the running angle of the motor rotor corresponding to the unit distance of the plunger running in the pump body, and the motor rotor angle corresponding to the plunger reaching the target limit position.

[0027] In some optional embodiments, determining the time interval required for the motor to run from the starting angle of the current operation cycle to the theoretical rotor angle includes:

[0028] Determine the angular interval from the starting angle of the current operation cycle of the motor to the theoretical rotor angle;

[0029] Based on the angular interval and the running speed of the motor rotor, a time interval required for the motor to run from the starting angle to the theoretical rotor angle is determined.

[0030] In some optional embodiments, increasing the stator voltage to a preset amplitude within a preset time includes:

[0031] Within a preset time interval, the stator voltage is increased by 60%-70% of the maximum output voltage of the inverter.

[0032] In some optional embodiments, determining the corrected rotor angle corresponding to the correction point using a voltage equation based on the increased stator voltage and the collected corresponding current, as well as the electromagnetic characteristic parameters of the motor, includes:

[0033] Convert the voltage equation of the permanent magnet synchronous motor into the d-axis voltage equation and the q-axis voltage equation in the dq coordinate system;

[0034] Determining a d-axis back electromotive force vector component using the d-axis voltage equation based on the increased stator voltage component on the d-axis, the corresponding stator current components on the d-axis and q-axis, the stator resistance, the stator inductance components on the d-axis and q-axis, and the rotor speed;

[0035] Determining a q-axis back electromotive force vector component using the q-axis voltage equation based on the increased stator voltage component on the q-axis, the corresponding stator current components on the d-axis and q-axis, the stator resistance, the stator inductance components on the d-axis and q-axis, and the rotor speed;

[0036] A correction rotor angle corresponding to the correction point is determined based on the d-axis back electromotive force vector component and the q-axis back electromotive force vector component.

[0037] In some optional embodiments, determining the d-axis back electromotive force vector component using the d-axis voltage equation based on the increased stator voltage component on the d-axis, the corresponding stator current components on the d-axis and q-axis, the stator resistance, the stator inductance components on the d-axis and q-axis, and the rotor speed includes:

[0038] Based on the increased stator voltage component on the d-axis, the corresponding stator current components on the d-axis and q-axis, the stator resistance, the stator inductance components on the d-axis and q-axis, and the rotor speed, the d-axis back EMF vector component is determined using the following formula:

[0039]

[0040] in, represents the d-axis back EMF vector component, It represents the voltage component of the increased voltage on the d-axis. represents the stator resistance, It represents the current component on the d-axis corresponding to the current after the voltage increases. represents the d-axis stator inductance component, represents the q-axis stator inductance component, It indicates the current component on the q axis corresponding to the voltage increase. Indicates the rotor speed.

[0041] In some optional embodiments, determining the q-axis back electromotive force vector component using the q-axis voltage equation based on the increased stator voltage component on the q-axis, the corresponding stator current components on the d-axis and q-axis, the stator resistance, the stator inductance components on the d-axis and q-axis, and the rotor speed includes:

[0042] Based on the increased stator voltage component on the q-axis, the corresponding stator current components on the d-axis and q-axis, the stator resistance, the stator inductance components on the d-axis and q-axis, and the rotor speed, the q-axis back EMF vector component is determined using the following formula:

[0043]

[0044] in, represents the q-axis back EMF vector component, It represents the voltage component of the increased voltage on the q axis, represents the stator resistance, It indicates the current component on the q axis corresponding to the voltage increase. represents the d-axis stator inductance component, represents the q-axis stator inductance component, It represents the current component on the d-axis corresponding to the current after the voltage increases. Indicates the rotor speed.

[0045] In some optional embodiments, determining the correction rotor angle corresponding to the correction point based on the d-axis back electromotive force vector component and the q-axis back electromotive force vector component includes:

[0046] determining a ratio of the d-axis back electromotive force vector component to the q-axis back electromotive force vector component;

[0047] Determine the arc tangent value of the ratio and obtain the correction rotor angle corresponding to the correction point.

[0048] In some optional embodiments, the arc tangent value of the ratio is determined to obtain the correction rotor angle corresponding to the correction point, which is specifically implemented using the following formula:

[0049]

[0050] in, represents the d-axis back EMF vector component, represents the q-axis back EMF vector component, Indicates the corrected rotor angle.

[0051] In some optional embodiments, the method further includes: before determining the correction rotor angle corresponding to the correction point, filtering the corresponding current collected after the stator voltage increases by using a Kalman filtering method.

[0052] An embodiment of the present invention further provides a permanent magnet electric submersible piston pump deceleration control device, comprising:

[0053] A determination module is used to determine the rotor angle corresponding to the deceleration point in the current operating cycle, specifically including: if the current operating cycle is the first operating cycle, determining the rotor angle corresponding to the deceleration point based on the self-learning result of the operating position of the plunger in the pump body and the corresponding rotor angle; otherwise, determining the rotor angle corresponding to the deceleration point based on the rotor angle and error angle corresponding to the deceleration point in the previous operating cycle; wherein, the process of determining the error angle corresponding to the deceleration point in the previous operating cycle includes: determining a theoretical rotor angle corresponding to a preset correction point, and determining the time interval required for the motor to run from the starting angle of the current operating cycle to the theoretical rotor angle; wherein, if the previous operating cycle is the first operating cycle, the theoretical rotor angle corresponding to the correction point is determined based on the self-learning result, otherwise it is the correction rotor angle corresponding to the correction point in the operating cycle before the previous operating cycle; after the motor runs from the starting angle for the said time interval, increasing the stator voltage to a preset amplitude within a preset time; determining the correction rotor angle corresponding to the correction point based on the increased stator voltage and the corresponding current collected, as well as the electromagnetic characteristic parameters of the motor; and determining the error angle based on the theoretical rotor angle corresponding to the correction point and the correction rotor angle.

[0054] The control module is used to reduce the driving current frequency of the motor so that the plunger of the permanent magnet submersible plunger pump decelerates to the target limit position when the angle of the motor rotor reaches the rotor angle corresponding to the preset deceleration point in the current operation cycle.

[0055] An embodiment of the present invention further provides a permanent magnet electric submersible piston pump deceleration control system, comprising:

[0056] Permanent magnet synchronous motor, used to convert electrical energy into mechanical energy to provide power for the plunger pump body;

[0057] The plunger pump body is used to realize the reciprocating motion of the plunger in the pump body under the action of the permanent magnet synchronous motor;

[0058] The permanent magnet electric submersible piston pump deceleration control device as described above is used to determine the rotor angle corresponding to the deceleration point in the current operation cycle, and when the angle of the motor rotor is consistent with the rotor angle, reduce the driving current frequency of the motor.

[0059] The beneficial effects of the above technical solutions provided by the embodiments of the present invention include at least:

[0060] A corresponding deceleration point is set in advance at a preset distance from the extreme position of the permanent magnet submersible piston pump body to ensure that the driving current frequency of the motor is reduced when the plunger moves to the deceleration point, thereby smoothly transitioning to the extreme position of the pump body and avoiding collision;

[0061] When determining the rotor angle corresponding to the deceleration point in the current operating cycle, in the first operating cycle, the upper and lower limit positions of the permanent magnet submersible piston pump are self-learned. Based on the self-learning results of the operating position of the plunger of the permanent magnet submersible piston pump in the pump body and the corresponding motor rotor angle, the rotor angle corresponding to the deceleration point is determined. The upper and lower limit position self-learning process reflects the actual working stroke of the plunger in the pump body, provides a basis for determining the rotor angle corresponding to the deceleration point, provides a relatively accurate basis for the first deceleration, and avoids the large initial error that may exist in a purely theoretical model.

[0062] However, due to the complex current fluctuations and the untimely response, the rotor angle corresponding to the deceleration point determined based on the self-learning results is not accurate enough. Therefore, a preset correction point is used to determine the error angle of the current cycle in each operating cycle. Specifically, the time interval required for the motor to run from the starting angle of the current operating cycle to the theoretical rotor angle corresponding to the correction point is determined; after the motor runs for the time interval from the starting angle, the actual value corresponding to the correction point is calculated by calculation, and the actual value corresponding to the correction point is calculated using the voltage equation of the permanent magnet synchronous motor based on the stator voltage, current, and electromagnetic characteristic parameters of the motor; however, due to the long distance of the cable and the temperature change of the permanent magnet synchronous motor, the resistance increases, resulting in an error in the value of the motor rotor angle calculated based on the voltage equation of the permanent magnet synchronous motor. Therefore, after the motor runs for the time interval, the voltage of the motor stator is increased by a preset amplitude within a preset time, thereby further increasing the stator current and the current change rate to compensate for the error in the value of the motor rotor angle caused by the increase in cable resistance. Based on the increased stator voltage and the corresponding current collected, as well as the electromagnetic characteristic parameters of the motor, the correction rotor angle corresponding to the correction point is determined; the error angle is determined based on the theoretical rotor angle of the correction point and the correction rotor angle.

[0063] In subsequent operating cycles, the error angle determined in the previous cycle is used to dynamically adjust the rotor angle corresponding to the deceleration point of the current cycle. Under this control strategy, it is possible to continuously learn and adapt to the actual operating status of the system, continuously correct deviations, and significantly improve the accuracy of the rotor angle corresponding to the deceleration point, thereby achieving accurate and reliable deceleration when the plunger approaches the target limit position, avoiding hard impact, extending the life of the pump, and compensating for errors accumulated over time or due to changes in permanent magnet motor parameters such as inductance, resistance, and permanent magnet flux during long-term operation.

[0064] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purposes and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings.

[0065] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0067] Figure 1 Flowchart of a deceleration control method for a permanent magnet electric submersible piston pump according to an embodiment of the present invention;

[0068] Figure 2 Flowchart of a method for determining a rotor angle corresponding to a deceleration point in a current operating cycle according to an embodiment of the present invention;

[0069] Figure 3 Flowchart of a method for determining an error angle corresponding to a deceleration point in the previous operating cycle according to an embodiment of the present invention;

[0070] Figure 4 Schematic diagram of the structure of the deceleration control device of the permanent magnet electric submersible piston pump in an embodiment of the present invention;

[0071] Figure 5 Schematic diagram of the structure of the permanent magnet submersible piston pump deceleration control system in an embodiment of the present invention. DETAILED DESCRIPTION

[0072] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0073] Glossary:

[0074] Motor driving current frequency: refers to the frequency of the AC current supplied to the motor stator winding, usually expressed in Hertz, which directly determines the synchronous speed of the motor.

[0075] To address the problem in the prior art of being unable to accurately and preemptively decelerate a permanent magnet submersible piston pump during operation to prevent the plunger from hitting the top or bottom of the pump body during operation, an embodiment of the present invention provides a deceleration control method for a permanent magnet submersible piston pump. Corresponding deceleration points and correction points are set at preset distances from the extreme positions of each pump body of the permanent magnet submersible piston pump. During the first operating cycle of the piston pump, the rotor angle corresponding to the deceleration point is determined based on the self-learning results of the piston pump, providing a basis for determining the rotor angle corresponding to the deceleration point. If it is not the first operating cycle, the rotor angle for the current operating cycle is determined using the rotor angle at the deceleration point determined in the previous cycle and the angle error determined based on the correction point. During the process of determining the error angle, it was unexpectedly discovered that the long cable distance and temperature changes of the motor cause the motor stator resistance to increase and become unstable, which affects the calculation of the rotor angle. The motor stator voltage is increased in the form of short pulses to compensate for the error caused by the unstable resistance. Furthermore, by correcting the rotor angle corresponding to the deceleration point in each operating cycle, the accumulation of rotor angle errors corresponding to the deceleration point is avoided, providing reliable support for the precise positioning of the deceleration point, and thus avoiding possible top or bottom collisions.

[0076] The embodiment of the present invention provides a method for controlling deceleration of a permanent magnet electric submersible piston pump, the process of which is as follows: Figure 1 Shown, including:

[0077] In order to effectively prevent the plunger from hitting the top and bottom of the pump body when it runs inside the pump body, when the plunger runs close to the top and bottom of the pump body, the driving current frequency of the motor is reduced so that the plunger decelerates to the extreme position of the pump body without violently colliding with the extreme position of the pump body. Therefore, it is necessary to set deceleration points at positions close to the top of the pump body and at positions close to the bottom of the pump body to reserve a buffer zone for the plunger to decelerate to the top and bottom of the pump body. Specifically, a top deceleration point is set at a first preset distance from the top of the permanent magnet submersible plunger pump pump body; a bottom deceleration point is set at a second preset distance from the bottom of the permanent magnet submersible plunger pump pump body. After the deceleration points are set, the following steps are performed, including:

[0078] Step S1: Determine the rotor angle corresponding to the deceleration point in the current operation cycle;

[0079] Step S2: In the current operation cycle, when the angle of the motor rotor reaches the rotor angle corresponding to the preset deceleration point, the driving current frequency of the motor is reduced to decelerate the plunger of the permanent magnet submersible plunger pump to reach the target limit position.

[0080] In some optional embodiments, in step S1, the rotor angle corresponding to the deceleration point in the current operation cycle is determined, and the process is as follows: Figure 2 Shown, including:

[0081] The plunger of a permanent magnet submersible piston pump performs periodic reciprocating motion within the pump body. The first time the plunger moves from the top of the pump body to the bottom and then back to the top, or the first time it moves from the bottom of the pump body to the top and then back to the bottom, is considered the plunger's first operating cycle within the pump body. When the plunger reaches its limit position, the rotor rotates in the opposite direction, and the plunger moves toward the other limit position.

[0082] If the current operating cycle is the first operating cycle, execute step S11: determine the rotor angle corresponding to the deceleration point based on the self-learning results of the operating position of the plunger in the pump body and the corresponding motor rotor angle; otherwise, execute step S12: determine the rotor angle corresponding to the deceleration point based on the rotor angle and error angle corresponding to the deceleration point in the previous operating cycle.

[0083] In some optional embodiments, in step S11, determining the rotor angle corresponding to the deceleration point based on the self-learning result of the operating position of the plunger in the pump body and the corresponding motor rotor angle includes:

[0084] The self-learning process of the plunger running in the pump body is as follows: start the permanent magnet submersible plunger pump and monitor the changes in the motor current in real time. By determining whether the current increase reaches a preset threshold, the moment when the plunger reaches the top and bottom of the pump body is identified, and the first motor rotor angle corresponding to the plunger reaching the top of the pump body and the second motor rotor angle corresponding to the plunger reaching the bottom of the pump body are recorded.

[0085] After the self-learning is completed, 1) the difference between the first motor rotor angle and the second motor rotor angle is determined; 2) based on the difference between the first motor rotor angle and the second motor rotor angle and the distance between the top and bottom of the pump body, the running angle of the motor rotor corresponding to the unit distance of the plunger running in the pump body is determined; 3) based on the distance between the deceleration point and the target limit position, the running angle of the motor rotor corresponding to the unit distance of the plunger running in the pump body, and the motor rotor angle corresponding to the plunger reaching the target limit position, the rotor angle corresponding to the deceleration point is determined.

[0086] Specifically, if the deceleration point is a top deceleration point, that is, the deceleration point is set at a first preset distance from the top of the pump body, close to the top of the pump body, then the rotor angle corresponding to the deceleration point is determined based on the distance between the deceleration point and the top of the pump body, the running angle of the motor rotor corresponding to the unit distance of the plunger running in the pump body, and the motor rotor angle corresponding to the plunger reaching the top of the pump body;

[0087] If the deceleration point is a bottom deceleration point, that is, it is set at a first preset distance from the bottom of the pump body, close to the bottom of the pump body, then the rotor angle corresponding to the deceleration point is determined based on the distance between the deceleration point and the bottom of the pump body, the running angle of the motor rotor corresponding to the unit distance of the plunger running in the pump body, and the motor rotor angle corresponding to the plunger reaching the bottom of the pump body.

[0088] In some optional embodiments, in step S12, determining the rotor angle corresponding to the deceleration point based on the rotor angle and the error angle corresponding to the deceleration point in the previous operation cycle includes:

[0089] In this step, it is necessary to determine the rotor angle corresponding to the deceleration point of the previous operating cycle and the error angle corresponding to the deceleration point of the previous operating cycle, so as to compensate for the error angle of the deceleration point in the next operating cycle and obtain a more accurate rotor angle.

[0090] Among them, the rotor angle corresponding to the deceleration point of the previous operating cycle can be known from the above logic: if the previous operating cycle is the first operating cycle, the rotor angle corresponding to the deceleration point is determined based on the self-learning result, see step S11; otherwise, it is determined based on the rotor angle and error angle of the previous operating cycle of this operating cycle. For example, if the previous operating cycle is the second operating cycle, the rotor angle corresponding to the deceleration point of the second operating cycle is determined based on the rotor angle and error angle of the first operating cycle; if the previous operating cycle is the third operating cycle, the rotor angle corresponding to the deceleration point of the third operating cycle is determined based on the rotor angle and error angle of the second operating cycle, and so on.

[0091] Among them, the process of determining the error angle corresponding to the deceleration point of the previous operation cycle is as follows: Figure 3 Shown, including:

[0092] A correction point is set at a second preset distance from a certain target limit position. In each operating cycle, the time interval required for the motor to run from the starting angle of the current operating cycle to the theoretical rotor angle corresponding to the correction point is determined; when the motor runs for the said time interval, the correction is triggered.

[0093] Specifically, step S121: determining a theoretical rotor angle corresponding to a preset calibration point, and determining a time interval required for the motor to run from a starting angle to the theoretical rotor angle corresponding to the calibration point;

[0094] Step S122: After the motor runs for the time interval from the starting angle, increasing the stator voltage to a preset amplitude within a preset time; determining a correction rotor angle corresponding to the correction point based on the increased stator voltage and the collected corresponding current, as well as the electromagnetic characteristic parameters of the motor;

[0095] Step S123: determining an error angle based on the theoretical rotor angle corresponding to the correction point and the correction rotor angle.

[0096] In some optional embodiments, in step S121, determining the theoretical rotor angle corresponding to the preset calibration point and determining the time interval required for the motor to run from the starting angle to the theoretical rotor angle corresponding to the calibration point specifically includes:

[0097] In this step, the theoretical rotor angle corresponding to the calibration point of the last operating cycle is determined, which is divided into the following two cases:

[0098] Case 1: If the previous operating cycle is the first operating cycle, the theoretical rotor angle corresponding to the correction point is determined based on the self-learning result; specifically, as in the self-learning process in step S11, after the self-learning is completed, 1) the difference between the first motor rotor angle and the second motor rotor angle is determined; 2) based on the difference between the first motor rotor angle and the second motor rotor angle, and the distance between the top and the bottom of the pump body, the running angle of the motor rotor corresponding to the unit distance of the pump body operation of the plunger is determined; 3) based on the distance between the correction point and the target limit position, the running angle of the motor rotor corresponding to the unit distance of the pump body operation of the plunger, and the motor rotor angle corresponding to the plunger reaching the target limit position, the rotor angle corresponding to the correction point is determined.

[0099] Case 2: If the previous operating cycle was not the first operating cycle, the theoretical rotor angle corresponding to the calibration point is the calibration rotor angle corresponding to the calibration point in the operating cycle before the previous operating cycle. For example, if the previous operating cycle was the second operating cycle, the theoretical rotor angle corresponding to the calibration point in the second operating cycle is the calibration rotor angle corresponding to the calibration point in the first operating cycle. If the previous operating cycle was the third operating cycle, the theoretical rotor angle corresponding to the calibration point in the third operating cycle is the calibration rotor angle corresponding to the calibration point in the second operating cycle, and so on. The process of determining the calibration rotor angle corresponding to the calibration point during operation is described in step S122.

[0100] After the theoretical rotor angle corresponding to the correction point is determined, the time interval required for the motor to run from the starting angle to the theoretical rotor angle is determined, including:

[0101] Determine the angular interval for the motor to run from the starting angle of the current operation cycle to the theoretical rotor angle; and determine the time interval required for the motor to run from the starting angle to the theoretical rotor angle based on the angular interval and the operating speed of the motor rotor.

[0102] In some optional embodiments, in step S122, after the motor runs for the time interval from the starting angle of the current cycle, the stator voltage is increased to a preset amplitude within a preset time; and based on the increased stator voltage and the collected corresponding current, as well as the electromagnetic characteristic parameters of the motor, a correction rotor angle corresponding to the correction point is determined, specifically including:

[0103] Step S1221: within a preset time interval, the stator voltage is increased by 60%-70% of the maximum output voltage of the inverter input voltage. Optionally, the motor stator voltage is increased to a preset amplitude within 0.3 ms.

[0104] In the application of permanent magnet submersible piston pumps, the long cable length and temperature fluctuations of the motor cause the motor stator resistance to increase and become unstable. If the voltage equation is used to directly determine the motor rotor angle based on the current and voltage corresponding to the currently acquired correction point, the increased stator resistance will cause the resulting back EMF vector to decrease, making it difficult to accurately determine the motor rotor angle corresponding to the correction point. To overcome this problem, by increasing the motor stator voltage in the form of short pulses, the corresponding stator current and current change rate will also increase, reducing the error in the back EMF vector and compensating for the decrease in back EMF vector caused by the increased resistance. This improves the accuracy of the motor rotor angle identification and ensures the rotor angle correction function corresponding to the correction point is implemented.

[0105] After a short pulse is injected, sudden voltage and current fluctuations are sampled instantaneously. However, due to the extremely short pulse duration, the generated torque is insufficient to overcome load inertia and friction. The rotor cannot respond to short-term torque fluctuations within milliseconds, and the rotor position remains virtually unchanged. Therefore, increasing the voltage primarily affects the transient response of the stator voltage and current to improve the accuracy of determining the motor's rotor angle. The voltage increase must ensure that the current changes significantly without causing the motor's rotor to move.

[0106] Step S1222: After the voltage is increased, the correction rotor angle corresponding to the correction point is determined using a voltage equation based on the increased stator voltage and the corresponding current collected, as well as the electromagnetic characteristic parameters of the motor. The electromagnetic characteristic parameters include static electromagnetic parameters and dynamic electromagnetic parameters. The static electromagnetic parameters include stator resistance and stator inductance, and the dynamic electromagnetic parameters include rotor, specifically including:

[0107] 1) Convert the voltage equation of the permanent magnet synchronous motor into the d-axis voltage equation and q-axis voltage equation in the dq coordinate system;

[0108] The d-axis voltage equation is:

[0109]

[0110] in, represents the d-axis back EMF vector component, represents the d-axis stator voltage component, represents the stator resistance, represents the d-axis stator current component, represents the d-axis stator inductance component, represents the q-axis stator inductance component, represents the q-axis stator current component, Indicates the rotor speed;

[0111] The q-axis voltage equation is:

[0112]

[0113] in, represents the q-axis back EMF vector component, represents the q-axis stator voltage component, represents the stator resistance, represents the q-axis stator current component, represents the d-axis stator inductance component, represents the d-axis stator current component, represents the q-axis stator inductance component, Indicates the rotor speed.

[0114] 2) Based on the increased stator voltage component on the d-axis, the corresponding stator current components on the d-axis and q-axis, the stator resistance, the stator inductance components on the d-axis and q-axis, and the rotor speed, the d-axis back EMF vector component is determined using the d-axis voltage equation; specifically, this is achieved using the following d-axis voltage equation:

[0115]

[0116] in, represents the d-axis back EMF vector component, It represents the voltage component of the increased voltage on the d-axis. represents the stator resistance, It represents the current component on the d-axis corresponding to the current after the voltage increases. represents the d-axis stator inductance component, represents the q-axis stator inductance component, It indicates the current component on the q axis corresponding to the voltage increase. Indicates the rotor speed.

[0117] 3) Based on the increased stator voltage component on the q-axis, the corresponding stator current components on the d-axis and q-axis, the stator resistance, the stator inductance components on the d-axis and q-axis, and the rotor speed, the q-axis back electromotive force vector component is determined using the q-axis voltage equation; specifically, the following q-axis voltage equation is used for implementation:

[0118]

[0119] in, represents the q-axis back EMF vector component, It represents the voltage component of the increased voltage on the q axis, represents the stator resistance, It indicates the current component on the q axis corresponding to the voltage increase. represents the d-axis stator inductance component, represents the q-axis stator inductance component, It represents the current component on the d-axis corresponding to the current after the voltage increases. Indicates the rotor speed.

[0120] 4) determining a correction rotor angle corresponding to the correction point based on the d-axis back electromotive force vector component and the q-axis back electromotive force vector component;

[0121] Determine the ratio of the d-axis back-electromotive force vector component to the q-axis back-electromotive force vector component; determine the arc tangent of the ratio to obtain the correction rotor angle corresponding to the correction point, which is specifically achieved using the following formula:

[0122]

[0123] in, represents the d-axis back EMF vector component, represents the q-axis back EMF vector component, Indicates the corrected rotor angle.

[0124] In some optional embodiments, since there is noise in the current sampling data, before executing step S1222, Kalman filtering is performed on the corresponding current sampled after the voltage is increased. This can effectively suppress measurement noise and disturbance noise and improve the accuracy of the motor rotor angle. Specifically, the following steps are performed:

[0125] 1) Selecting a d-axis stator current component, a q-axis stator current component, a rotor speed, and a rotor angle as state variables; establishing state equations and output equations for the state variables, and initializing the state variables;

[0126] 2) Discretize the state equation and add the system noise to obtain the discretized state equation, discretize the output equation and add the measurement noise to obtain the discretized output equation; and initialize the covariance of the system noise and the covariance of the measurement noise respectively;

[0127] 3) Based on the optimal state estimate at the previous moment and the actual applied voltage, the discretized state equation is used to predict the estimated values ​​of the stator current, rotor speed, and rotor angle at the current moment, and the error covariance of this state prediction is estimated. The expected current measurement value is determined using the predicted state estimate at the current moment and the discretized output equation.

[0128] 4) Fusion update based on the expected current measurement value at the current moment and the actual current collected, including:

[0129] ① Calculate the residual between the expected current measurement value at the current moment and the actual current collected;

[0130] ② Dynamically calculate the Kalman gain matrix based on the covariance of the current state prediction error and the covariance of the measurement noise;

[0131] ③ Based on the Kalman gain matrix, the predicted stator current and the collected stator current are fused to obtain the optimal stator current at the current moment, which is the filtered stator current value.

[0132] In some optional embodiments, in step S2, during the current operating cycle, when the angle of the motor rotor reaches the rotor angle corresponding to the preset deceleration point, the frequency of the motor's drive current is reduced to decelerate the plunger of the permanent magnet electric submersible piston pump to a target limit position. The current frequency and mechanical speed of the rotor of the permanent magnet synchronous motor are directly proportional to each other. When the motor's drive current frequency is reduced, the rotor speed decreases, thereby decelerating the plunger within the pump body.

[0133] In some optional embodiments, if abnormal current, abnormal vibration, or the rotor angle corresponding to the deceleration point in the current operating cycle cannot be normally identified during the operation of the plunger pump, emergency braking is performed to stop the reciprocating motion of the plunger pump to avoid damage to the equipment.

[0134] In the method of this embodiment, a short voltage pulse is used to reduce the influence of resistance increase and instability on the rotor angle, and the Kalman filtering method is used to suppress the interference of noise in the collected current, thereby realizing the correction of the rotor angle corresponding to each deceleration point, overcoming the problem of response lag or inaccuracy of traditional methods, and improving the accuracy of positioning the deceleration point. The characteristic that the motor speed and current frequency of the permanent magnet synchronous motor are consistent is utilized. When the rotor angle corresponding to the deceleration point is located, the driving current frequency of the motor is reduced, so that the plunger is decelerated to reach the target limit position corresponding to the deceleration point, thereby effectively avoiding or reducing the "top collision" and "bottom collision" phenomena during operation, improving the safety and stability of the system operation, and significantly extending the service life of the plunger pump.

[0135] Example 2:

[0136] A second embodiment of the present invention provides a specific implementation process of a deceleration control method for a permanent magnet electric submersible piston pump, including:

[0137] 1) A bottom deceleration point is set at a first preset distance from the bottom of the pump body, and a correction point is set at a second preset distance; a top deceleration point is set at a first preset distance from the top of the pump body; wherein the first preset distance is greater than the second preset distance;

[0138] In each operating cycle, the calibration is triggered when the plunger runs from top to bottom through the calibration point.

[0139] 2) Perform a self-learning process of the plunger running in the pump body to obtain a self-learning result of the running position of the plunger in the pump body and the corresponding motor rotor angle. For the specific process, refer to the self-learning process in step S11 of embodiment 1.

[0140] 3) In the first operating cycle, if the plunger first moves from the top to the bottom of the pump body, then:

[0141] ① Determine the rotor angle corresponding to the bottom deceleration point based on the self-learning results; when the motor rotor angle reaches the rotor angle corresponding to the bottom deceleration point, reduce the motor drive current frequency to decelerate the plunger of the permanent magnet submersible plunger pump to reach the target limit position;

[0142] ② Determine the theoretical rotor angle corresponding to the calibration point based on the self-learning result, and determine the time interval required for the motor to run from the starting angle to the theoretical rotor angle corresponding to the calibration point. For the specific determination process, see step S121;

[0143] ③ After the motor runs for the time interval from the starting angle, the stator voltage is increased to a preset amplitude within a preset time; based on the increased stator voltage and the corresponding current collected, as well as the electromagnetic characteristic parameters of the motor, a correction rotor angle corresponding to the correction point is determined. For a specific determination process, see step S122; the corresponding current collected after the stator voltage is increased can be filtered before calculating the correction rotor angle to improve the accuracy of the correction rotor angle;

[0144] determining an error angle based on a theoretical rotor angle corresponding to the correction point and a correction rotor angle;

[0145] ④ Based on the determined error angle, the rotor angle corresponding to the bottom of the pump body is updated. When the angle of the motor rotor reaches the rotor angle corresponding to the updated target limit position, the motor returns to normal speed and commutation is completed;

[0146] ⑤ Based on the determined error angle, the rotor angle corresponding to the top deceleration point after commutation is updated. When the angle of the motor rotor reaches this rotor angle, the driving current frequency of the motor is reduced to decelerate the plunger of the permanent magnet submersible piston pump to reach the top of the pump body. Optionally, in the first operating cycle, the rotor angle corresponding to the top deceleration point obtained based on self-learning is directly used as the deceleration angle.

[0147] 4) In the second run cycle:

[0148] ① The plunger runs from top to bottom: Based on the error angle of the first operating cycle and the rotor angle corresponding to the bottom deceleration point, the rotor angle corresponding to the deceleration point in the current operating cycle is determined; when the angle of the motor rotor reaches the rotor angle corresponding to the deceleration point in the current operating cycle, the motor drive current frequency is reduced to decelerate the plunger of the permanent magnet submersible plunger pump to reach the target limit position;

[0149] ② Obtain the correction rotor angle corresponding to the first operating cycle correction point, and determine the time interval required for the motor to run from the starting angle of the current operating cycle to the correction rotor angle;

[0150] ③ After the motor runs for the time interval from the starting angle, repeat the steps of increasing the stator voltage in the first operation cycle to correct the rotor angle corresponding to the correction point, and determine the error angle of the current operation cycle;

[0151] ④ Based on the error angle determined in the current cycle, the rotor angle corresponding to the bottom of the pump body is updated again. When the angle of the motor rotor reaches the rotor angle corresponding to the updated target limit position, the motor resumes normal speed and commutation is completed;

[0152] ⑤ Obtain the updated rotor angle of the top deceleration point in the first operating cycle. On this basis, update the rotor angle corresponding to the top deceleration point again based on the error angle determined in the current cycle. When the angle of the motor rotor reaches this rotor angle, reduce the driving current frequency of the motor so that the plunger of the permanent magnet submersible piston pump decelerates and reaches the top of the pump body.

[0153] The above steps are repeated in subsequent cycles, and the rotor angle of the deceleration point of the current cycle is dynamically determined using the error angle determined in the previous cycle and the rotor angle corresponding to the deceleration point.

[0154] In this embodiment, in the process of determining the correction rotor angle of the correction point, the stator voltage is briefly increased, and the angle is identified by combining the current response and the electromagnetic characteristic parameters of the motor. The motor itself is cleverly used as a sensor, eliminating the need to install physical position sensors that are prone to failure in the harsh environment underground, thereby greatly improving the long-term operation reliability under harsh working conditions.

[0155] By introducing correction points, the corrected rotor angle calculated based on the correction points in each operating cycle is compared with the theoretical value, and the systematic angle error is calculated. This error is then fed back into the setting of the deceleration point, effectively compensating for the cumulative errors caused by motor parameter drift, mechanical wear, load changes, etc., and significantly improving the deceleration accuracy and reliability of the plunger at the target limit position.

[0156] Based on the same inventive concept, the embodiment of the present invention further provides a permanent magnet electric submersible piston pump deceleration control device 10, the structure of which is as follows: Figure 4 Shown, including:

[0157] The determination module 101 is configured to determine the rotor angle corresponding to the deceleration point in the current operating cycle. Specifically, the determination module 101 includes: if the current operating cycle is the first operating cycle, determining the rotor angle corresponding to the deceleration point based on the self-learning result of the operating position of the plunger in the pump body and the corresponding rotor angle; otherwise, determining the rotor angle corresponding to the deceleration point based on the rotor angle and error angle corresponding to the deceleration point in the previous operating cycle; wherein the process of determining the error angle corresponding to the deceleration point in the previous operating cycle includes:

[0158] Determining a theoretical rotor angle corresponding to a preset calibration point, and determining a time interval required for the motor to run from a starting angle of a current operating cycle to the theoretical rotor angle; wherein if the previous operating cycle is the first operating cycle, the theoretical rotor angle corresponding to the calibration point is determined based on the self-learning result; otherwise, the calibration rotor angle corresponding to the calibration point in the operating cycle before the previous operating cycle is determined;

[0159] After the motor runs for the time interval from the starting angle, the stator voltage is increased to a preset amplitude within a preset time; based on the increased stator voltage and the corresponding current collected, as well as the electromagnetic characteristic parameters of the motor, the correction rotor angle corresponding to the correction point is determined; and the error angle is determined based on the theoretical rotor angle corresponding to the correction point and the correction rotor angle.

[0160] The control module 102 is configured to reduce the motor driving current frequency to decelerate the plunger of the permanent magnet submersible piston pump to a target limit position when the motor rotor angle reaches the rotor angle corresponding to the preset deceleration point in the current operation cycle.

[0161] The embodiment of the present invention also provides a permanent magnet electric submersible piston pump deceleration control system, the structure of the system is as follows Figure 5 Shown, including:

[0162] The permanent magnet electric submersible piston pump 20 is used to realize the reciprocating motion of the plunger in the pump body under the action of the permanent magnet synchronous motor;

[0163] The permanent magnet electric submersible piston pump deceleration control device 10 as described above is used to determine the rotor angle corresponding to the deceleration point in the current operation cycle, and reduce the driving current frequency of the motor when the angle of the motor rotor is consistent with the rotor angle.

[0164] Regarding the permanent magnet electric submersible piston pump deceleration control device in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method and will not be elaborated here.

[0165] The above-mentioned method and device of the embodiment of the present invention no longer rely on mechanical springs or simple current thresholds to determine the position of the deceleration point. They can effectively reduce the mechanical impact caused by "hitting the top" and "hitting the bottom", and adapt to the working conditions of the plunger pump under different well depths and different load conditions.

[0166] Unless otherwise specifically stated, terms such as process, calculate, compute, determine, display, and the like may refer to the actions and / or processes of one or more processing or computing systems, or similar devices, that manipulate and convert data represented as physical (e.g., electronic) quantities within registers or memories of a processing system into other data similarly represented as physical quantities within the memories, registers, or other such information storage, transmission, or display devices of the processing system. Information and signals may be represented using any of a variety of different techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips referred to throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, light fields or particles, or any combination thereof.

[0167] It should be understood that the specific order or hierarchy of steps in the disclosed processes is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process can be rearranged without departing from the scope of the present disclosure. The accompanying method claims present elements of the various steps in an exemplary order and are not intended to be limited to the specific order or hierarchy described.

[0168] In the foregoing detailed description, various features are grouped together in a single embodiment to simplify the disclosure. This method of disclosure should not be interpreted as reflecting an intention that embodiments of the claimed subject matter require more features than are expressly recited in each claim. On the contrary, as reflected in the appended claims, the invention comprises less than all the features of any individual disclosed embodiment. The appended claims are therefore hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment of the invention.

[0169] Those skilled in the art will also appreciate that the various illustrative logic blocks, modules, circuits, and algorithmic steps described in conjunction with the embodiments herein may be implemented as electronic hardware, computer software, or a combination thereof. In order to clearly illustrate the interchangeability between hardware and software, the various illustrative components, blocks, modules, circuits, and steps described above are generally described around their functions. Whether such functions are implemented as hardware or software depends on the specific application and the design constraints imposed on the entire system. A skilled person may implement the described functions in an adaptable manner for each specific application, but such implementation decisions should not be interpreted as departing from the scope of protection of this disclosure.

[0170] The steps of the methods or algorithms described in conjunction with the embodiments herein may be directly embodied as hardware, software modules executed by a processor, or a combination thereof. The software module may be located in a RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, register, hard disk, removable disk, CD-ROM, or any other form of storage medium well known in the art. An exemplary storage medium is connected to the processor so that the processor can read information from the storage medium and write information to the storage medium. Of course, the storage medium may also be an integral part of the processor. The processor and storage medium may be located in an ASIC. The ASIC may be located in a user terminal. Of course, the processor and storage medium may also be present in a user terminal as discrete components.

[0171] For software implementation, the techniques described in this application can be implemented using modules (e.g., procedures, functions, etc.) that perform the functions described in this application. These software codes can be stored in a memory unit and executed by a processor. The memory unit can be implemented within the processor or external to the processor. In the latter case, it is communicatively coupled to the processor via various means, which are well known in the art.

[0172] The foregoing description includes examples of one or more embodiments. Of course, it is not possible to describe all possible combinations of components or methods for the purposes of describing the above embodiments, but one of ordinary skill in the art will recognize that the various embodiments may be further combined and arranged. Therefore, the embodiments described herein are intended to encompass all such changes, modifications and variations that fall within the scope of the appended claims. Furthermore, to the extent the term "comprising" is used in the specification or claims, the term is intended to be encompassed in a manner similar to the term "including," as explained in terms of "including," used as a transitional word in the claims. Furthermore, any use of the term "or" in the specification of the claims is intended to mean a "non-exclusive or."

Claims

1. A method for controlling deceleration of a permanent magnet electric submersible piston pump, characterized in that: include: In the current operating cycle, when the angle of the motor rotor reaches the rotor angle corresponding to the preset deceleration point, the motor drive current frequency is reduced to decelerate the plunger of the permanent magnet submersible piston pump to reach the target limit position; wherein, if the current operating cycle is the first operating cycle, the rotor angle corresponding to the deceleration point is determined based on the self-learning results of the operating position of the plunger in the pump body and the corresponding rotor angle; Otherwise, the rotor angle corresponding to the deceleration point is determined based on the rotor angle and error angle corresponding to the deceleration point in the previous operating cycle. The process of determining the error angle corresponding to the deceleration point in the previous operating cycle includes: Determining a theoretical rotor angle corresponding to a preset calibration point, and determining a time interval required for the motor to run from a starting angle of a current operating cycle to the theoretical rotor angle; wherein if the previous operating cycle is the first operating cycle, the theoretical rotor angle corresponding to the calibration point is determined based on the self-learning result; otherwise, the calibration rotor angle corresponding to the calibration point in the operating cycle before the previous operating cycle is determined; After the motor runs for the time interval from the starting angle, the stator voltage is increased to a preset amplitude within a preset time; based on the increased stator voltage and the corresponding current collected, as well as the electromagnetic characteristic parameters of the motor, a voltage equation is used to determine the correction rotor angle corresponding to the correction point; and the error angle is determined based on the theoretical rotor angle corresponding to the correction point and the correction rotor angle.

2. The method according to claim 1, wherein The self-learning process of the plunger running in the pump body includes: Start the permanent magnet submersible piston pump and monitor the changes in motor current in real time. By determining whether the current increase reaches a preset threshold, the moment when the plunger reaches the top and bottom of the pump body is identified, and the first motor rotor angle corresponding to the plunger reaching the top of the pump body and the second motor rotor angle corresponding to the plunger reaching the bottom of the pump body are recorded.

3. The method according to claim 1, wherein The method of determining the rotor angle corresponding to the deceleration point based on the self-learning result of the operating position of the plunger in the pump body and the corresponding rotor angle includes: determining a difference between an angle of a rotor of the first motor and an angle of a rotor of the second motor; Based on the difference and the distance between the top and bottom of the pump body, determining the running angle of the motor rotor corresponding to the unit distance of the plunger running in the pump body; The rotor angle corresponding to the deceleration point is determined based on the distance between the deceleration point and the target limit position, the running angle of the motor rotor corresponding to the unit distance of the plunger running in the pump body, and the motor rotor angle corresponding to the plunger reaching the target limit position.

4. The method according to claim 3, wherein The determining of the rotor angle corresponding to the deceleration point based on the distance between the deceleration point and the target limit position, the running angle of the motor rotor corresponding to the unit distance of the plunger running in the pump body, and the motor rotor angle corresponding to the plunger reaching the target limit position includes: If the deceleration point is set at a preset distance from the top of the pump body, the rotor angle corresponding to the deceleration point is determined based on the distance between the deceleration point and the top of the pump body, the running angle of the motor rotor corresponding to the unit distance of the plunger running in the pump body, and the motor rotor angle corresponding to the plunger reaching the top of the pump body; If the deceleration point is set at a preset distance from the bottom of the pump body, the rotor angle corresponding to the deceleration point is determined based on the distance between the deceleration point and the bottom of the pump body, the running angle of the motor rotor corresponding to the unit distance of the plunger running in the pump body, and the motor rotor angle corresponding to the plunger reaching the bottom of the pump body.

5. The method according to claim 2, wherein If the last operating cycle is the first operating cycle, the theoretical rotor angle corresponding to the correction point is determined based on the self-learning result, including: determining a difference between an angle of a rotor of the first motor and an angle of a rotor of the second motor; Based on the difference and the distance between the top and bottom of the pump body, determining the running angle of the motor rotor corresponding to the unit distance of the plunger running in the pump body; The rotor angle corresponding to the calibration point is determined based on the distance between the calibration point and the target limit position, the running angle of the motor rotor corresponding to the unit distance of the plunger running in the pump body, and the motor rotor angle corresponding to the plunger reaching the target limit position.

6. The method according to claim 1, wherein Determining the time interval required for the motor to run from the starting angle of the current operation cycle to the theoretical rotor angle includes: Determine the angular interval from the starting angle of the current operation cycle of the motor to the theoretical rotor angle; Based on the angular interval and the running speed of the motor rotor, a time interval required for the motor to run from the starting angle to the theoretical rotor angle is determined.

7. The method according to claim 1, wherein Increasing the stator voltage to a preset amplitude within a preset time includes: Within a preset time interval, the stator voltage is increased by 60%-70% of the maximum output voltage of the inverter.

8. The method according to claim 1, wherein The method of determining the corrected rotor angle corresponding to the correction point by using a voltage equation based on the increased stator voltage and the collected corresponding current, as well as the electromagnetic characteristic parameters of the motor, includes: Convert the voltage equation of the permanent magnet synchronous motor into the d-axis voltage equation and the q-axis voltage equation in the dq coordinate system; Determining a d-axis back electromotive force vector component using the d-axis voltage equation based on the increased stator voltage component on the d-axis, the corresponding stator current components on the d-axis and q-axis, the stator resistance, the stator inductance components on the d-axis and q-axis, and the rotor speed; Determining a q-axis back electromotive force vector component using the q-axis voltage equation based on the increased stator voltage component on the q-axis, the corresponding stator current components on the d-axis and q-axis, the stator resistance, the stator inductance components on the d-axis and q-axis, and the rotor speed; A correction rotor angle corresponding to the correction point is determined based on the d-axis back electromotive force vector component and the q-axis back electromotive force vector component.

9. The method according to claim 8, wherein The method of determining the d-axis back electromotive force vector component using the d-axis voltage equation based on the increased stator voltage component on the d-axis, the corresponding stator current components on the d-axis and q-axis, the stator resistance, the stator inductance components on the d-axis and q-axis, and the rotor speed includes: Based on the increased stator voltage component on the d-axis, the corresponding stator current components on the d-axis and q-axis, the stator resistance, the stator inductance components on the d-axis and q-axis, and the rotor speed, the d-axis back EMF vector component is determined using the following formula: ； in, represents the d-axis back EMF vector component, It represents the voltage component of the increased voltage on the d-axis. represents the stator resistance, It represents the current component on the d-axis corresponding to the current after the voltage increases. represents the d-axis stator inductance component, represents the q-axis stator inductance component, It indicates the current component on the q axis corresponding to the voltage increase. Indicates the rotor speed.

10. The method according to claim 8, wherein The method of determining the q-axis back electromotive force vector component using the q-axis voltage equation based on the increased stator voltage component on the q-axis, the corresponding stator current components on the d-axis and q-axis, the stator resistance, the stator inductance components on the d-axis and q-axis, and the rotor speed includes: Based on the increased stator voltage component on the q-axis, the corresponding stator current components on the d-axis and q-axis, the stator resistance, the stator inductance components on the d-axis and q-axis, and the rotor speed, the q-axis back EMF vector component is determined using the following formula: ； in, represents the q-axis back EMF vector component, It represents the voltage component of the increased voltage on the q axis, represents the stator resistance, It indicates the current component on the q axis corresponding to the voltage increase. represents the d-axis stator inductance component, represents the q-axis stator inductance component, It represents the current component on the d-axis corresponding to the current after the voltage increases. Indicates the rotor speed.

11. The method according to claim 8, wherein The step of determining a correction rotor angle corresponding to a correction point based on the d-axis back electromotive force vector component and the q-axis back electromotive force vector component includes: determining a ratio of the d-axis back electromotive force vector component to the q-axis back electromotive force vector component; Determine the arc tangent value of the ratio and obtain the correction rotor angle corresponding to the correction point.

12. The method according to claim 11, wherein The arc tangent value of the ratio is determined to obtain the correction rotor angle corresponding to the correction point, which is specifically achieved using the following formula: ； in, represents the d-axis back EMF vector component, represents the q-axis back EMF vector component, Indicates the corrected rotor angle.

13. The method according to claim 1, wherein Also includes: Before determining the correction rotor angle corresponding to the correction point, the corresponding current collected after the stator voltage increases is filtered using the Kalman filtering method.

14. A permanent magnet electric submersible piston pump deceleration control device, characterized in that: include: A determination module is used to determine the rotor angle corresponding to the deceleration point in the current operating cycle, specifically including: if the current operating cycle is the first operating cycle, determining the rotor angle corresponding to the deceleration point based on the self-learning result of the operating position of the plunger in the pump body and the corresponding rotor angle; otherwise, determining the rotor angle corresponding to the deceleration point based on the rotor angle and error angle corresponding to the deceleration point in the previous operating cycle; wherein, the process of determining the error angle corresponding to the deceleration point in the previous operating cycle includes: determining the theoretical rotor angle corresponding to a preset correction point, and determining the time interval required for the motor to run from the starting angle of the current operating cycle to the theoretical rotor angle; wherein, if the previous operating cycle is the first operating cycle, the theoretical rotor angle corresponding to the correction point is determined based on the self-learning result, otherwise it is the correction rotor angle corresponding to the correction point in the operating cycle before the previous operating cycle; after the motor runs from the starting angle for the said time interval, increasing the stator voltage to a preset amplitude within a preset time; determining the correction rotor angle corresponding to the correction point based on the increased stator voltage and the corresponding current collected, as well as the electromagnetic characteristic parameters of the motor; determining the error angle based on the theoretical rotor angle corresponding to the correction point and the correction rotor angle; The control module is used to reduce the driving current frequency of the motor so that the plunger of the permanent magnet submersible plunger pump decelerates to the target limit position when the angle of the motor rotor reaches the rotor angle corresponding to the preset deceleration point in the current operation cycle.

15. A permanent magnet electric submersible piston pump deceleration control system, characterized in that: include: Permanent magnet synchronous motor, used to convert electrical energy into mechanical energy to provide power for the plunger pump body; The plunger pump body is used to realize the reciprocating motion of the plunger in the pump body under the action of the permanent magnet synchronous motor; The deceleration control device for a permanent magnet electric submersible piston pump according to claim 14 is configured to determine a rotor angle corresponding to a deceleration point in a current operating cycle, and to reduce the drive current frequency of the motor when the angle of the motor rotor is consistent with the rotor angle.

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