A special closed-loop control system and method for submersible screw pumps based on a trial pumping algorithm

Abstract

The present invention provides a closed-loop control system for a submersible screw pump based on a trial pumping algorithm, comprising a data acquisition unit, a sensor, a frequency conversion control unit, a unit, a remote transmission unit, a background monitoring unit and a display unit, wherein the unit, the sensor and the data acquisition unit are connected in sequence, the data acquisition unit is connected to the unit through the frequency conversion control unit, the data acquisition unit is also connected to the display unit and the remote transmission unit, the remote transmission unit is connected to the background monitoring unit, and the background monitoring unit is connected to the data acquisition unit. The present invention shortens the submergence of the submersible screw pump when it is started and the time to reach the target submergence, and can make the submergence quickly reach the target submergence.

Description

Technical Field

[0001] The invention relates to the technical field of submersible screw pumps, and in particular to a closed-loop control system and method for submersible screw pumps based on a trial pumping algorithm. Background Art

[0002] At present, submersible screw pumps are suitable for discharging viscous liquids and liquids containing solid phases, and the flow rate is uniform and stable, thus being widely used. However, the difficulty in starting the screw pump and the long time to reach the target sinking degree also reduce the utilization rate of the submersible screw pump.

[0003] With the continuous development of oil fields, the submergence of oil wells has become an important parameter for oil fields to control the oil well liquid level. It is also extremely important to quickly make the submergence reach the target submergence. Rapidly stabilizing the submergence can avoid unnecessary problems such as equipment damage and unauthorized downtime, so that the oil well can operate normally. Therefore, a closed-loop control model dedicated to screw pumps is needed to quickly stabilize the submergence so that the submergence can quickly reach the target value. Summary of the invention

[0004] In view of this, the present invention provides a closed-loop control system and method for a submersible screw pump based on a trial pumping algorithm, which shortens the submersible screw pump's sinking depth when it is started and the time to reach a target sinking depth, and can make the sinking depth quickly reach the target sinking depth.

[0005] In order to solve the above technical problems, the present invention provides a special closed-loop control system for submersible screw pumps based on a trial pumping algorithm, including a data acquisition unit, a sensor, a frequency conversion control unit, a unit, a remote transmission unit, a background monitoring and a display unit. The unit, the sensor and the data acquisition unit are connected in sequence, the data acquisition unit is connected to the unit through the frequency conversion control unit, the data acquisition unit is also connected to the display unit and the remote transmission unit, the remote transmission unit is connected to the background monitoring, and the background monitoring is connected to the data acquisition unit.

[0006] Furthermore, the sensors include a voltage sensor, a current sensor, a temperature sensor, a rotation speed monitoring module for monitoring the unit, a flow transmitter for monitoring pipeline flow, and a pressure sensor for monitoring casing pressure and back pressure.

[0007] Furthermore, the data acquisition unit includes a control module, and the control module includes a GSM8594 integrated block and a KE02 digital signal processor.

[0008] Furthermore, the remote transmission unit is composed of a GPRS module, and the data processed by the data acquisition unit is transmitted to the background monitoring by the remote transmission unit.

[0009] A closed-loop control method for a submersible screw pump based on a trial pumping algorithm first compares the actual submergence with the target submergence. When the target submergence is smaller than the actual submergence, the motor speed is increased; when the target submergence is larger than the actual submergence, the motor speed is reduced, the current motor speed is changed, and finally the speed is output.

[0010] Furthermore, two control modes, single-order closed-loop and double-order closed-loop, are adopted. After each PID adjustment cycle, the required motor speed is calculated by detecting the sinking degree, motor temperature, output speed, pressure, voltage, current and flow operating parameters, combined with the closed-loop control setting parameters.

[0011] Furthermore, when single-order closed-loop control is adopted, after starting the system, the speed is fine-tuned by using an incremental algorithm based on the difference between the submergence and the target submergence, thereby controlling the operating speed.

[0012] Further, the incremental algorithm u=|M1-M2|×k,

[0013] Speed ​​adjustment value: u, unit: rpm,

[0014] Target sinking degree: M1, unit meter,

[0015] Actual sinking degree: M2, unit meter,

[0016] Adjustment factor: k, the proportional relationship between the submergence deviation value and the increase in rotation speed.

[0017] Furthermore, when the double-order closed-loop control is adopted, the running speed of the motor is adjusted using the incremental algorithm and the trial extraction algorithm;

[0018] When the difference between the actual submergence and the target submergence is greater than 10 meters, the trial pumping algorithm is used to calculate the motor speed corresponding to the liquid supply volume and adjust it;

[0019] When the difference between the actual submergence depth and the target submergence depth is less than 10 meters, the incremental algorithm is used to adjust the motor speed.

[0020] Furthermore, the trial pumping algorithm is used to calculate the motor speed N that matches the current oil well fluid supply. 1 , assuming the following conditions:

[0021] Assuming the pump displacement Q 1 and the speed of the screw pump N 2 Proportional to Q 1 =K 1 ×N 2 ×T, T is time, K 1 is the pump displacement coefficient,

[0022] Assume that the oil well supply is stable in a short period of time; when the pump speed is N1 When the supply and production balance is reached, the oil well supply is equal to the pump displacement:

[0023] Q 2 =Q 1 =K 1 ×N 1 ×T

[0024] When the height is higher than the target sinking degree, the height is set to 10 meters, and the maximum speed N of the PID is set. 3 Run and record the time T taken for the sinking depth to drop by 10 meters 1 , calculate the amount of liquid that falls 10 meters:

[0025] V 1 =Q 3 – Q 4 =(K 1 ×N 3 ×T 1 )-( K 1 ×N 1 ×T 1 )

[0026] When the sinking depth is 10 meters below the set target, the vehicle will rotate at the set PID minimum speed N 4 Run and record the time T taken for the sinking depth to rise by 10 meters 2 , calculate the amount of liquid that rises 10 meters:

[0027] V 2 =Q 5 -Q 6 =(K 1 ×N 1 ×T 2 )-(K 1 ×N 4 ×T 2 )

[0028] From the above, we can achieve:

[0029] Casing capacity of 10 meters down = casing capacity of 10 meters up

[0030] V 1 =V 2

[0031] Q 3 -Q 4 =Q 5 -Q 6

[0032] (K 1 ×N 3 ×T 1 )-(K 1 ×N1 ×T 1 )=(K 1 ×N 1 ×T 2 )-(K 1 ×N 4 ×T 2 )

[0033] N1=((N 3 ×T 1 )+(N 4 ×T 2 )) / (T 1 +T 2 )

[0034] N 3 : High speed value,

[0035] T 1 : The time taken for the sinking depth to decrease by 10 meters,

[0036] N 4 : Low speed value,

[0037] T 2 : The time taken for the sinking depth to rise by 10 meters,

[0038] N 1 : The motor speed corresponding to the supply and demand balance,

[0039] V 1 : When the current sinking degree is higher than the target sinking degree, the amount of liquid required to reduce the sinking degree.

[0040] V 2 : The amount of liquid required to increase the sinking degree when the current sinking degree is lower than the target sinking degree.

[0041] Q 3 : The amount of liquid discharged at high speed when the submergence is higher than the target value,

[0042] Q 4 : The amount of liquid discharged at the current speed when the submergence is higher than the target value,

[0043] Q 6 : The amount of liquid discharged at the lowest speed when the submergence is lower than the target value,

[0044] Q 5 : The amount of fluid discharged at the current speed when the submergence is lower than the target value.

[0045] The beneficial effects of the above technical solution of the present invention are as follows:

[0046] The control system is mainly controlled by the data acquisition unit, which collects the status of the unit through sensors for information processing, and sends it to the background monitoring system and frequency conversion control unit after processing. The frequency conversion control unit performs closed-loop operation on the unit through the frequency converter, and then the unit feeds back the status after operation to the sensor to form a closed-loop operation.

[0047] The main control algorithm is composed of a calculation method and a closed-loop processing, wherein the calculation method is composed of an incremental algorithm and a trial pumping algorithm, and the closed-loop processing is composed of a single-stage closed-loop processing and a double-stage closed-loop processing. The present invention shortens the time between the submersible screw pump's submergence when it is started and the time to reach the target submergence, and can make the submergence quickly reach the target submergence.

[0048] The closed-loop regulation used by conventional submersible screw pumps is to slowly reduce the submergence until the submergence reaches the target value, while the dedicated closed-loop control model first uses the maximum speed to quickly reduce the submergence, and then adjusts the speed to slowly reduce the submergence to reach the target submergence when the target submergence is almost reached. Compared with the closed-loop regulation of conventional submersible screw pumps, the dedicated closed-loop control model has the following advantages: 1) Fast response speed, the motor speed can be quickly adjusted according to the target submergence to reach the target submergence in the shortest time. 2) Adapting to the development needs of the oil field, when the submergence of the oil well fluctuates greatly, the dedicated closed-loop control model can quickly stabilize the liquid level. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 is a system structure diagram of the control system of the present invention;

[0050] Figure 2 This is the incremental algorithm diagram of the present invention;

[0051] Figure 3 It is a single-order closed-loop control diagram of the present invention;

[0052] Figure 4 This is a double-order closed-loop control diagram of the present invention. DETAILED DESCRIPTION

[0053] To make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the following will be combined with the appended drawings of the embodiments of the present invention. Figure 1-4 , the technical scheme of the embodiment of the present invention is clearly and completely described. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0054] Embodiment 1

[0055] The present embodiment provides a special closed-loop control system for submersible screw pumps based on a trial pumping algorithm, including a data acquisition unit, a sensor, a frequency conversion control unit, a unit, a remote transmission unit, a background monitoring and a display unit. The unit, the sensor and the data acquisition unit are connected in sequence. The data acquisition unit is connected to the unit through the frequency conversion control unit. The data acquisition unit is also connected to the display unit and the remote transmission unit. The remote transmission unit is connected to the background monitoring, and the background monitoring is connected to the data acquisition unit.

[0056] The system transmits the information collected by the sensor to the data acquisition unit for data processing. After the data acquisition unit processes the information, it sends the processed information to the inverter and the remote transmission unit. After the inverter receives the information from the data acquisition unit, it controls the unit accordingly. After receiving the information from the data acquisition unit, the remote transmission unit transmits the information remotely to the monitoring background for real-time monitoring.

[0057] The sensors include a voltage sensor, a current sensor, a temperature sensor, a rotation speed monitoring module for monitoring the unit, a flow transmitter for monitoring pipeline flow, and a pressure sensor for monitoring casing pressure and back pressure.

[0058] The data acquisition unit comprises a control module, and the control module comprises a GSM8594 integrated block and a KE02 digital signal processor.

[0059] The remote transmission unit is composed of a GPRS module, and the data processed by the data acquisition unit is transmitted to the background monitoring by the remote transmission unit.

[0060] The main control algorithm exists in the data acquisition unit. The sensor collects the voltage, current, temperature and other signals of the downhole motor and transmits the downhole situation to the data acquisition unit in digital mode. The GSM8594 integrated block of the data acquisition unit processes the information and summarizes it to the main control algorithm of the integrated block. The main control algorithm feeds back the processed information to the inverter and the remote transmission unit. The inverter adjusts the operating status of the unit based on the processed information, and the remote transmission unit transmits it remotely to the background monitoring software through the GPRS module. The main control algorithm of the data acquisition unit is divided into calculation method and closed-loop processing. The calculation method is divided into incremental algorithm and trial extraction algorithm. The closed-loop processing is divided into single-order closed-loop and double-order closed-loop.

[0061] Embodiment 2

[0062] The present embodiment provides a special closed-loop control method for a submersible screw pump based on a trial pumping algorithm. First, by comparing the actual sinking depth with the target sinking depth, when the target sinking depth is less than the actual sinking depth, the motor speed is increased; when the target sinking depth is greater than the actual sinking depth, the motor speed is reduced, the current motor speed is changed, and finally the speed is output.

[0063] It adopts two control modes: single-order closed-loop and double-order closed-loop. After each PID adjustment cycle, the required motor speed is calculated by detecting the sinking degree, motor temperature, output speed, pressure, voltage, current and flow operating parameters, combined with the closed-loop control setting parameters.

[0064] When single-order closed-loop control is adopted, after starting the system, the speed is fine-tuned by using the incremental algorithm based on the difference between the submergence depth and the target submergence depth, thereby controlling the operating speed.

[0065] Incremental algorithm u=|M1-M2|×k,

[0066] Speed ​​adjustment value: u, unit: revolutions per minute,

[0067] Target sinking degree: M1, unit meter,

[0068] Actual sinking degree: M2, unit meter,

[0069] Adjustment factor: k, the proportional relationship between the submergence deviation value and the increase in rotation speed.

[0070] When adopting double-order closed-loop control, the incremental algorithm and trial-draw algorithm are used to adjust the running speed of the motor;

[0071] When the difference between the actual submergence and the target submergence is greater than 10 meters, the trial pumping algorithm is used to calculate the motor speed corresponding to the liquid supply volume and adjust it;

[0072] When the difference between the actual submergence depth and the target submergence depth is less than 10 meters, the incremental algorithm is used to adjust the motor speed.

[0073] Use the trial pumping algorithm to calculate the motor speed N that matches the current oil well fluid supply. 1 , assuming the following conditions:

[0074] Assuming the pump displacement Q 1 and the speed of the screw pump N 2 Proportional to Q 1 =K 1 ×N 2 ×T, T is time, K 1 is the pump displacement coefficient,

[0075] Assume that the oil well supply is stable in a short period of time; when the pump speed is N 1 When the supply and production balance is reached, the oil well supply is equal to the pump displacement:

[0076] Q 2 =Q 1 =K 1 ×N 1 ×T

[0077] When the height is higher than the target sinking degree, the height is set to 10 meters, and the maximum speed N of the PID is set. 3 Run and record the time T taken for the sinking depth to drop by 10 meters 1 , calculate the amount of liquid that falls 10 meters:

[0078] V 1 =Q 3 – Q 4 =(K 1 ×N 3 ×T 1 )-( K 1 ×N 1 ×T 1 )

[0079] When the sinking depth is 10 meters below the set target, the vehicle will rotate at the set PID minimum speed N 4 Run and record the time T taken for the sinking depth to rise by 10 meters 2 , calculate the amount of liquid that rises 10 meters:

[0080] V 2 =Q 5 -Q 6 =(K 1 ×N 1 ×T 2 )-(K 1 ×N 4 ×T 2 )

[0081] From the above, we can achieve:

[0082] Casing capacity of 10 meters down = casing capacity of 10 meters up

[0083] V 1 =V 2

[0084] Q 3 -Q 4 =Q 5 -Q 6

[0085] (K 1 ×N 3 ×T 1 )-(K 1 ×N 1 ×T 1 )=(K 1 ×N 1 ×T 2 )-(K 1 ×N 4 ×T 2 )

[0086] N1=((N 3 ×T 1 )+(N 4 ×T 2 )) / (T 1 +T 2 )

[0087] N 3 : High speed value,

[0088] T 1 : The time taken for the sinking depth to decrease by 10 meters,

[0089] N 4 : Low speed value,

[0090] T 2 : The time taken for the sinking depth to rise by 10 meters,

[0091] N 1 : The motor speed corresponding to the supply and demand balance,

[0092] V 1 : When the current sinking degree is higher than the target sinking degree, the amount of liquid required to reduce the sinking degree.

[0093] V 2 : The amount of liquid required to increase the sinking degree when the current sinking degree is lower than the target sinking degree.

[0094] Q 3 : The amount of liquid discharged at high speed when the submergence is higher than the target value,

[0095] Q 4 : The amount of liquid discharged at the current speed when the submergence is higher than the target value,

[0096] Q 6 : The amount of liquid discharged at the lowest speed when the submergence is lower than the target value,

[0097] Q 5 : The amount of fluid discharged at the current speed when the submergence is lower than the target value.

[0098] In the present invention, unless otherwise clearly stipulated and limited, for example, it can be a fixed connection, a detachable connection, or an integrated one; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. Unless otherwise clearly defined, for ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0099] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A closed-loop control method for a submersible screw pump based on a trial pumping algorithm, characterized in that: The control system used in the closed-loop control method includes a data acquisition unit, a sensor, a frequency conversion control unit, a machine set, a remote transmission unit, a background monitoring unit and a display unit. The machine set, the sensor and the data acquisition unit are connected in sequence. The data acquisition unit is connected to the machine set through the frequency conversion control unit. The data acquisition unit is also connected to the display unit and the remote transmission unit. The remote transmission unit is connected to the background monitoring unit, and the background monitoring unit is connected to the data acquisition unit. The closed-loop control method comprises: firstly comparing the actual submergence with the target submergence, and when the target submergence is smaller than the actual submergence, increasing the motor speed; when the target submergence is larger than the actual submergence, reducing the motor speed, and finally outputting the speed; It adopts single-order closed-loop and double-order closed-loop control modes. After each PID adjustment cycle, the required motor speed is calculated by detecting the actual sinking degree, motor temperature, output speed, pressure, voltage, current and flow operating parameters, combined with the closed-loop control setting parameters; When the single-order closed-loop control mode is adopted, after the control system is started, the difference between the actual submergence and the target submergence is calculated, and the speed is fine-tuned using the incremental algorithm to control the motor speed; Incremental algorithm u=|M1-M2|×k, Speed ​​adjustment value: u, unit: revolutions per minute, Target sinking degree: M1, unit meter, Actual sinking degree: M2, unit meter, Adjustment factor: k, the proportional relationship between the submergence deviation and the increase in rotation speed; When the two-stage closed-loop control mode is adopted, the motor speed is adjusted using the incremental algorithm and the trial extraction algorithm: when the difference between the actual submergence and the target submergence is greater than 10 meters, the trial extraction algorithm is used to calculate the motor speed corresponding to the liquid supply volume and adjust it; when the difference between the actual submergence and the target submergence is less than 10 meters, the incremental algorithm is used to adjust the motor speed; The trial pumping algorithm is used to calculate the motor speed N1 when the current oil well supply and production are balanced, assuming the following conditions: Assume that the pump displacement Q1 is proportional to the speed N2 of the screw pump, Q1 = K1 × N2 × T, T is the working time of the screw pump, K1 is the pump displacement coefficient, Assume that the fluid supply of the oil well is stable in a short period of time; when the speed of the screw pump is N1, the supply-production balance is reached, and the fluid supply of the oil well is equal to the pump displacement: Q2=Q1=K1×N1×T When the sinking depth is 10 meters higher than the set target, it runs at the set PID maximum speed N3, and records the time T1 used for the sinking depth to drop by 10 meters, and calculates the liquid volume dropped by 10 meters: V1=Q3–Q4=(K1×N3×T1)-(K1×N1×T1) When the sinking depth is 10 meters lower than the set target, it runs at the set PID minimum speed N4, and records the time T2 used for the sinking depth to rise by 10 meters, and calculates the liquid volume that rises by 10 meters: V2=Q5-Q6=(K1×N1×T2)-(K1×N4×T2) From the above, we can achieve: Casing capacity of 10 meters down = casing capacity of 10 meters up V1=V2 Q3-Q4=Q5-Q6 (K1×N3×T1)-(K1×N1×T1)=(K1×N1×T2)-(K1×N4×T2) N1=((N3×T1)+(N4×T2)) / (T1+T2) N3: PID maximum speed value, T1: The time it takes for the sinking depth to drop by 10 meters. N4: PID minimum speed value, T2: The time it takes for the sinking depth to rise by 10 meters. N1: Motor speed corresponding to supply and demand balance, V1: When the current sinking degree is higher than the target sinking degree, the amount of liquid required to reduce the sinking degree. V2: The amount of liquid required to increase the sinking depth when the current sinking depth is lower than the target sinking depth. Q3: Displacement at high speed when the submergence is higher than the target value, Q4: The amount of liquid discharged at the current speed when the submergence is higher than the target value. Q6: Discharge volume at the lowest speed when the submergence is lower than the target value, Q5: The amount of liquid discharged at the current speed when the submergence is lower than the target value.

2. The closed-loop control method for a submersible screw pump based on a trial pumping algorithm as claimed in claim 1, characterized in that: The sensors include a voltage sensor, a current sensor, a temperature sensor, a rotation speed monitoring module for monitoring the unit, a flow transmitter for monitoring pipeline flow, and a pressure sensor for monitoring casing pressure and back pressure.

3. The closed-loop control method for a submersible screw pump based on a trial pumping algorithm as claimed in claim 2, characterized in that: The data acquisition unit comprises a control module, and the control module comprises a GSM8594 integrated block and a KE02 digital signal processor.

4. The closed-loop control method for a submersible screw pump based on a trial pumping algorithm as claimed in claim 3, characterized in that: The remote transmission unit is composed of a GPRS module, and the data processed by the data acquisition unit is transmitted to the background monitoring by the remote transmission unit.

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