Control method and apparatus for lifting system

Abstract

The present disclosure relates to the technical field of offshore platform lifting, and provides a control method and apparatus for a lifting system. The lifting system comprises a plurality of pile legs, each of the pile legs is provided with a plurality of lifting units, each of the lifting units comprises a variable frequency motor, and the plurality of variable frequency motors on each of the pile legs comprise a main motor and a plurality of slave motors. The control method comprises: for any one of the pile legs, respectively determining parameter information of the plurality of variable frequency motors on the pile leg, the parameter information comprising an actual rotation speed, an estimated load, a theoretical rotation speed and a theoretical load, the theoretical rotation speeds of the plurality of variable frequency motors being identical, and the theoretical loads of the plurality of variable frequency motors being identical; and on the basis of the parameter information of the plurality of variable frequency motors, respectively adjusting the actual rotation speeds of the plurality of variable frequency motors, so that the difference between the actual rotation speed and the theoretical rotation speed of each of the variable frequency motors and the difference between the estimated load and the theoretical load of each of the variable frequency motors are both within a threshold range.

Description

Control methods and control devices for lifting systems

[0001] This application claims priority to Chinese Patent Application No. 202510088109.3, filed on January 21, 2025, entitled "Control Method and Control Device for Lifting System", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure belongs to the field of offshore platform lifting technology, and specifically relates to a control method and control device for a lifting system. Background Technology

[0003] Rack and pinion lifting systems for offshore platforms are widely used. These systems utilize variable frequency motors for drive, and their cleanliness, efficiency, and ease of maintenance have led to their increasing application in the lifting system field. Each leg of the variable frequency drive rack and pinion lifting system has multiple lifting units. Each lifting unit includes a variable frequency motor, a gearbox, and a pinion gear mounted on the gearbox's output shaft. The pinion gear meshes with a rack on the leg, and the variable frequency motor drives the pinion gear on the gearbox's output shaft to rotate, thereby raising or lowering the leg via the rack. Due to the large tonnage of offshore platforms, the lifting system requires synchronized operation of all variable frequency motors during the lifting process.

[0004] In related technologies, to synchronize the working status of the various variable frequency motors on each pile leg, a master-slave speed control method is generally adopted for the multiple variable frequency motors corresponding to each pile leg. One variable frequency motor is selected as the master motor, and the others are slave motors. When the speed difference between the master motor and the slave motor exceeds a speed threshold, the speed of the slave motor is automatically controlled until the speed difference does not exceed the speed threshold.

[0005] However, the above control method only considers the consistency of the speed of all variable frequency motors, which leads to a large load deviation between the various variable frequency motors. This means that the offshore platform may still be unstable and have poor lifting performance. Summary of the Invention

[0006] This disclosure provides a control method and control device for a lifting system, which can improve the lifting stability of offshore platforms. The technical solution is as follows:

[0007] On one hand, this disclosure provides a control method for a lifting system. The lifting system includes multiple legs, each leg is equipped with multiple lifting units, each lifting unit includes a variable frequency motor, and the multiple variable frequency motors on each leg include a main motor and multiple slave motors. The control method includes:

[0008] For any given pile leg, determine the parameter information of multiple variable frequency motors on the pile leg. The parameter information includes the actual speed, estimated load, theoretical speed, and theoretical load. The theoretical speeds of the multiple variable frequency motors are the same, and the theoretical loads of the multiple variable frequency motors are the same.

[0009] Based on the parameter information of multiple variable frequency motors, the actual speed of each variable frequency motor is adjusted so that the difference between the actual speed and the theoretical speed of each variable frequency motor, and the difference between the estimated load and the theoretical load, are all within the threshold range.

[0010] In one implementation of this disclosure, parameter information of multiple variable frequency motors on the pile legs is determined, including:

[0011] Obtain commands sent from the offshore platform's control system to the main motor, including speed values;

[0012] Based on the speed values ​​in the instructions, determine the theoretical speeds of multiple variable frequency motors;

[0013] Obtain the actual speeds of multiple variable frequency motors detected by a rotary encoder;

[0014] Based on the theoretical and actual speeds of multiple variable frequency motors, the estimated load of multiple variable frequency motors is calculated;

[0015] The theoretical load of multiple variable frequency motors is determined based on the load capacity of the offshore platform.

[0016] In another implementation of this disclosure, the estimated load of the multiple variable frequency motors is calculated based on their theoretical and actual speeds, including:

[0017] The estimated load of the variable frequency motor can be calculated using the following formula:

[0018] Where Ti is the estimated load of the i-th variable frequency motor, i≤n; n represents the number of variable frequency motors; Let be the theoretical speed of the i-th variable frequency motor; is the actual speed of the i-th variable frequency motor; r is the droop coefficient.

[0019] In another implementation of this disclosure, the actual speeds of the multiple variable frequency motors are adjusted according to their parameter information, including:

[0020] Calculate the speed difference between the actual speed and the theoretical speed of multiple variable frequency motors, and calculate the load difference between the estimated load and the theoretical load of multiple variable frequency motors.

[0021] If the absolute value of the speed difference of any variable frequency motor is greater than the speed threshold, and / or if the absolute value of the load difference of any variable frequency motor is greater than the load threshold, adjust the actual speed of at least one variable frequency motor among the multiple variable frequency motors until the absolute value of the speed difference of all variable frequency motors is no greater than the speed threshold, and the absolute value of the load difference of all variable frequency motors is no greater than the load threshold.

[0022] In another implementation of this disclosure, the speed difference between the actual speed and the theoretical speed of multiple variable frequency motors is calculated, including:

[0023] The difference between the actual speed and the theoretical speed of the variable frequency motor can be calculated using the following formula:

[0024] Where ΔVi represents the difference between the actual speed and the theoretical speed of the i-th variable frequency motor, i≤n; n represents the number of variable frequency motors; Vi represents the actual speed of the i-th variable frequency motor; and V0 represents the theoretical speed.

[0025] In another implementation of this disclosure, the load difference between the estimated load and the theoretical load of multiple variable frequency motors is calculated, including:

[0026] The load difference between the estimated load and the theoretical load of the variable frequency motor is calculated using the following formula:

[0027] Where ΔTi represents the load difference between the estimated load and the theoretical load of the i-th variable frequency motor, i≤n; n represents the number of variable frequency motors; Ti represents the estimated load of the i-th variable frequency motor; and T0 represents the theoretical load.

[0028] In another implementation of this disclosure, adjusting the actual speed of at least one of the multiple variable frequency motors includes:

[0029] When the speed difference ΔVi of the i-th variable frequency motor is greater than 0, the actual speed of the i-th variable frequency motor is adjusted to Vii = Vi(1-|ΔVi|);

[0030] Alternatively, when the speed difference ΔVi of the i-th variable frequency motor is less than 0, the actual speed of the i-th variable frequency motor is adjusted to Vii = Vi(1 + |ΔVi|).

[0031] Where ΔVi represents the speed difference of the i-th variable frequency motor, Vi represents the actual speed of the i-th variable frequency motor, and Vii represents the adjustment target value of the actual speed of the i-th variable frequency motor.

[0032] In another implementation of this disclosure, adjusting the actual speed of at least one of the multiple variable frequency motors further includes:

[0033] When the lifting system is in the lifting platform mode or the lowering leg mode, and the load difference ΔTi of the i-th variable frequency motor is greater than 0, the actual speed of the i-th variable frequency motor is adjusted to Vii = Vi(1 + |ΔTi|); or, when the lifting system is in the lifting platform mode or the lowering leg mode, and the load difference ΔTi of the i-th variable frequency motor is less than 0, the actual speed of the i-th variable frequency motor is adjusted to Vii = Vi(1 - |ΔTi|).

[0034] When the lifting system is in the lowering platform mode or the raising leg mode, and the load difference ΔTi of the i-th variable frequency motor is greater than 0, the actual speed of the i-th variable frequency motor is adjusted to Vii = Vi(1-|ΔTi|); or, when the lifting system is in the lowering platform mode or the raising leg mode, and the load difference ΔTi of the i-th variable frequency motor is less than 0, the actual speed of the i-th variable frequency motor is adjusted to Vii = Vi(1+|ΔTi|).

[0035] Where ΔTi represents the load difference of the i-th variable frequency motor, Vi represents the actual speed of the i-th variable frequency motor, and Vii represents the adjustment target value of the actual speed of the i-th variable frequency motor.

[0036] On the other hand, this disclosure also provides a control device for a lifting system. The lifting system includes multiple legs, each leg is provided with multiple lifting units, each lifting unit includes a variable frequency motor, and the multiple variable frequency motors on each leg include a main motor and multiple slave motors. The control device includes a determination module and an adjustment module.

[0037] The determination module is used to determine the parameter information of multiple variable frequency motors on any given pile leg. The parameter information includes the actual speed, estimated load, theoretical speed, and theoretical load. The theoretical speeds of the multiple variable frequency motors are the same, and the theoretical loads of the multiple variable frequency motors are the same.

[0038] The adjustment module is used to adjust the actual speed of multiple variable frequency motors according to the parameter information of multiple variable frequency motors, so that the difference between the actual speed and the theoretical speed of each variable frequency motor, and the difference between the estimated load and the theoretical load are all within the threshold range.

[0039] On the other hand, embodiments of this disclosure also provide a computer device, the computer device including a processor and a memory configured to store processor-executable instructions; the processor is configured to execute the control method of the lifting system described above.

[0040] On the other hand, this disclosure also provides a computer storage medium storing computer instructions, which, when executed by a processor, implement the control method of the lifting system described above. Attached Figure Description

[0041] Figure 1 is a flowchart of a control method for a lifting system provided in an embodiment of this disclosure;

[0042] Figure 2 is a flowchart of another control method for a lifting system provided in an embodiment of this disclosure;

[0043] Figure 3 is a structural block diagram of a control device for a lifting system provided in an embodiment of this disclosure;

[0044] Figure 4 is a structural block diagram of a computer device provided in an embodiment of this disclosure. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0046] This disclosure provides a control method applied to a lifting system. The lifting system includes multiple legs, each leg equipped with multiple lifting units. Each lifting unit includes a variable frequency motor, a gearbox, and a pinion gear mounted on the output shaft of the gearbox. The variable frequency motor is connected to the input end of the gearbox. When the variable frequency motor starts, it drives the pinion gear to rotate via the gearbox. The rotating pinion gear then meshes with a rack on the leg, thereby raising or lowering the leg.

[0047] Figure 1 is a flowchart of a control method for a lifting system provided in an embodiment of this disclosure. This method can be executed by the control system of an offshore platform. As shown in Figure 1, the control method for the lifting system includes:

[0048] 101: For any given pile leg, determine the parameter information of multiple variable frequency motors on the pile leg. The parameter information includes the actual speed, estimated load, theoretical speed, and theoretical load. The theoretical speeds of the multiple variable frequency motors are the same, and the theoretical loads of the multiple variable frequency motors are the same.

[0049] For a single pile leg, the multiple variable frequency motors on that pile leg include a main motor and multiple slave motors. The main motor is any one of the multiple variable frequency motors on that pile leg, and the slave motors include all the variable frequency motors on that pile leg except for the main motor; that is, there are multiple slave motors.

[0050] In this embodiment of the disclosure, the main motor in the variable frequency motor is electrically connected to the control system of the offshore platform. The control system inputs commands to the main motor to control its speed. The main motor is also electrically connected to other slave motors. The main motor sends commands to the other slave motors to output the received commands from the control system to each slave motor, thereby controlling the speed of the slave motors.

[0051] In other words, the control system of the offshore platform can send the control command of the main motor directly to the main motor, and the control system of the offshore platform can also forward the control command of each slave motor to each slave electrode through the main motor.

[0052] In other words, to simplify the control system, one of the variable frequency motors is electrically connected to the control system of the offshore platform, while the other slave motors only need to be electrically connected to the main motor to receive commands.

[0053] During adjustment, the control system first inputs a setpoint to the main motor to control its speed. Upon receiving this setpoint, the main motor synchronously inputs the same setpoint to the slave motor to control its speed.

[0054] The actual speed and estimated load of the variable frequency motor are the motor's current actual speed and the load estimated based on the actual speed. This estimated load is close to the actual load, but saves on load measurement and simplifies the hardware system.

[0055] The theoretical speed and theoretical load of a variable frequency motor are the theoretical speed and load of the variable frequency motor under the control of the commands sent by the control system.

[0056] 102: Based on the parameter information of multiple variable frequency motors, the actual speed of each variable frequency motor is adjusted so that the difference between the actual speed and the theoretical speed of each variable frequency motor, and the difference between the estimated load and the theoretical load, are all within the threshold range.

[0057] The threshold range corresponding to the difference between the actual speed and the theoretical speed, and the threshold range corresponding to the difference between the estimated load and the theoretical load, may be the same or different.

[0058] For example, setting speed thresholds and load thresholds separately will form threshold ranges corresponding to the difference between actual speed and theoretical speed, and threshold ranges corresponding to the difference between estimated load and theoretical load, respectively.

[0059] By ensuring that the difference between the actual speed and theoretical speed of each variable frequency motor, and the difference between the estimated load and the theoretical load, are all within the threshold range, the speed and load of multiple variable frequency motors on the same pile leg are synchronized.

[0060] In this embodiment of the disclosure, the adjustment in step 102 refers to the control system of the offshore platform adjusting the speed of the main motor or the slave motor by sending a command.

[0061] In this embodiment of the disclosure, the control system of the offshore platform can periodically execute the control method to achieve a balance between rotational speed and load during the lifting and lowering process.

[0062] The control method provided in this embodiment first determines the actual speed and estimated load of the main motor and slave motor on each pile leg. Then, based on the actual speed of the main motor, the actual speed of each slave motor, the theoretical speed of the main motor, the estimated load of the main motor, the estimated load of each slave motor, and the theoretical load, the actual speeds of the slave motors and the main motor are adjusted so that the actual speeds of the slave motors and the main motors are synchronized with their theoretical speeds, and the estimated loads of the slave motors and the main motors are synchronized with their theoretical loads. This ensures that the actual speeds and loads of each variable frequency motor are synchronized, improving the stability of the lifting system. In other words, this control method not only synchronizes the actual speeds of each variable frequency motor but also synchronizes their loads, simultaneously achieving a balanced synchronization of the actual speeds and loads of the variable frequency motors.

[0063] In this embodiment of the disclosure, the load of the variable frequency motor refers to the mechanical load experienced by the variable frequency motor during operation, including inertial load, frictional load, and other loads. It is the resistance or demand generated by the mechanical load on the motor, and is usually expressed as a percentage.

[0064] Load also describes the ratio between the output torque and rated torque of a variable frequency motor, thus reflecting the motor's load condition and operating status. For example, when the motor's torque percentage is close to or reaches 100%, it indicates that the motor is operating at its rated torque. At this time, the motor has a large load, strong torque output capability, and high working efficiency, while 0% indicates no load. With a fixed power, as the motor speed increases, its torque will decrease accordingly; conversely, as the speed decreases, the torque will increase accordingly. Therefore, the motor load can be adjusted by changing the speed.

[0065] Figure 2 is a flowchart of another control method for a lifting system provided in an embodiment of this disclosure. This method can be executed by the control system of an offshore platform. As shown in Figure 2, the control method for the lifting system includes:

[0066] 201: Determine the actual speed of the main motor and each slave motor on each pile leg, and estimate the load.

[0067] In this embodiment, the offshore platform has four legs. Each leg has 12 variable frequency motors. The 12 variable frequency motors are arranged in multiple pairs along the length of the leg, with each pair consisting of two motors. The two motors in each pair are located on opposite sides of the leg. One of the motors in the third pair from the top is the master motor, and the rest are slave motors.

[0068] For example, the actual rotational speed of each variable frequency motor on each pile leg can be recorded as Vi. i represents the number of the variable frequency motor, and the value of i is a natural number from 1 to 12, corresponding to 12 variable frequency motors respectively.

[0069] The actual speed of the variable frequency motor can be detected by a rotary encoder. For example, the rotary encoder is connected to the output terminal of the variable frequency motor to detect the actual speed of the output terminal of the variable frequency motor in real time. That is, the actual speeds of multiple variable frequency motors detected by the rotary encoder can be obtained.

[0070] Since the variable frequency motor is automatically controlled by the control system of the offshore platform, the control system of the offshore platform inputs different commands into the variable frequency motor. These commands are used to indicate the speed value, which can correspondingly change the input current of the variable frequency motor, thereby changing the theoretical speed of the variable frequency motor.

[0071] Therefore, the process of determining the theoretical speed of the variable frequency motor is as follows: obtain the command sent by the control system of the offshore platform to the main motor, which includes the speed value; and determine the theoretical speed of multiple variable frequency motors based on the speed value in the command.

[0072] For example, the speed value in the control system commands of an offshore platform is V. number The corresponding theoretical speed V of the variable frequency motor ref (Also known as the reference speed, in r / min) is:

[0073] According to the above formula (1), when the speed value in the command of the control system of the offshore platform is 20000, the corresponding reference speed of the variable frequency motor is 2500r / min.

[0074] The theoretical speed is the desired speed value of the variable frequency motor set by the control system of the offshore platform. Ideally, the actual speed of the variable frequency motor should equal the theoretical speed. However, due to factors such as load changes, power fluctuations, and mechanical losses, the actual speed deviates from the theoretical speed.

[0075] Therefore, based on the above relationship, it can be seen that the estimated load of multiple variable frequency motors can be calculated based on the theoretical and actual speeds of multiple variable frequency motors.

[0076] In this embodiment of the disclosure, the estimated load of each slave motor and the master motor can be calculated according to the following empirical formula (2).

[0077] Where Ti is the estimated load of the i-th variable frequency motor; Let be the theoretical speed of the i-th variable frequency motor; is the actual speed of the i-th variable frequency motor; r is the droop coefficient.

[0078] In this embodiment of the disclosure, r can take the value of 0.03.

[0079] In other words, the estimated load of each variable frequency motor can be directly calculated using the above formula.

[0080] In addition, the theoretical load of multiple variable frequency motors is determined based on the load of the offshore platform. For example, the sum of the load and self-weight of the offshore platform is calculated, and then the load is allocated based on the number of legs and the number of variable frequency motors on each leg. Combined with the current working conditions (the load is corrected based on the correction coefficient determined by the working conditions, and the correction coefficient is an empirical value), the theoretical load of multiple variable frequency motors on each leg is determined.

[0081] 202: Calculate the actual speed of the main motor and the speed difference between the actual speed and the theoretical speed of each slave motor.

[0082] In this embodiment of the disclosure, the speed difference refers to the ratio of the difference between the actual speed and the theoretical speed to the theoretical speed.

[0083] The actual speed of the main motor and the speed difference between the actual speed and the theoretical speed of each slave motor are calculated using the following formulas:

[0084] Where ΔVi represents the difference between the actual speed and the theoretical speed of the i-th variable frequency motor, i≤n, n represents the number of variable frequency motors, Vi represents the actual speed of the i-th variable frequency motor, and V0 represents the theoretical speed (i.e., V0). ref ).

[0085] In this embodiment of the disclosure, after obtaining the actual speed of each variable frequency motor detected by the rotary encoder, the speed difference between each slave motor and the master motor can be calculated by formula (3).

[0086] 203: Calculate the estimated load of the main motor and the load difference between the estimated load of each slave motor and the theoretical load.

[0087] In this embodiment of the disclosure, the load difference refers to the ratio of the difference between the estimated load and the theoretical load to the theoretical load.

[0088] The estimated load of the main motor and the load difference between the estimated load of each slave motor and the theoretical load are calculated using the following formulas:

[0089] Where ΔTi represents the load difference between the estimated load and the theoretical load of the i-th variable frequency motor, i≤n; n represents the number of variable frequency motors; Ti represents the estimated load of the i-th variable frequency motor; and T0 represents the theoretical load.

[0090] In this embodiment of the disclosure, after the estimated load of each slave motor and the master motor is calculated according to formula (2), the estimated load difference between each slave motor and the master motor can be calculated by formula (4).

[0091] 204: When the absolute value of the speed difference is greater than the speed threshold, and / or when the absolute value of the load difference is greater than the load threshold, adjust the actual speed of the main motor or the slave motor until the absolute value of the speed difference is not greater than the speed threshold and the absolute value of the load difference is not greater than the load threshold.

[0092] In this embodiment of the disclosure, the rotational speed threshold can be a value between 0 and 0.2. The load threshold can also be a value between 0 and 0.2.

[0093] In one possible implementation, the actual speed can be adjusted first based on the speed difference, and then the actual speed can be adjusted based on the load difference.

[0094] In another possible implementation, the actual speed is adjusted based solely on the load difference.

[0095] Optionally, step 204 includes the following:

[0096] 2041: When the speed difference ΔVi of the i-th variable frequency motor is greater than 0, adjust the actual speed of the i-th variable frequency motor to Vii = Vi(1-|ΔVi|); or, when the speed difference ΔVi of the i-th variable frequency motor is less than 0, adjust the actual speed of the i-th variable frequency motor to Vii = Vi(1+|ΔVi|).

[0097] Where ΔVi represents the speed difference of the i-th variable frequency motor, Vi represents the actual speed of the i-th variable frequency motor, and Vii represents the adjustment target value of the actual speed of the i-th variable frequency motor.

[0098] In this embodiment of the disclosure, when the speed difference ΔVi > 0, it indicates that Vi > V0, meaning the actual speed of the master motor or slave motor is greater than the theoretical speed. Therefore, the actual speed of the master motor or slave motor needs to be reduced. Thus, ΔVi can be reduced based on the current actual speed of the master motor or slave motor. When the speed difference ΔVi < 0, it indicates that Vi < V0, meaning the actual speed of the master motor or slave motor is less than the theoretical speed. Therefore, the actual speed of the master motor or slave motor needs to be increased. Thus, ΔVi can be increased based on the current actual speed of the master motor or slave motor.

[0099] When ΔVi = 0, the actual speed of the i-th variable frequency motor remains unchanged.

[0100] 2042: When the lifting system is in the lifting platform mode or the lowering leg mode, and the load difference ΔTi of the i-th variable frequency motor is greater than 0, adjust the actual speed of the i-th variable frequency motor to Vii = Vi(1 + |ΔTi|); or, when the lifting system is in the lifting platform mode or the lowering leg mode, and the load difference ΔTi of the i-th variable frequency motor is less than 0, adjust the actual speed of the i-th variable frequency motor to Vii = Vi(1 - |ΔTi|).

[0101] Alternatively, when the lifting system is in the lowering platform mode or the raising leg mode, and the load difference ΔTi of the i-th variable frequency motor is greater than 0, the actual speed of the i-th variable frequency motor is adjusted to Vii = Vi(1-|ΔTi|); or, when the lifting system is in the lowering platform mode or the raising leg mode, and the load difference ΔTi of the i-th variable frequency motor is less than 0, the actual speed of the i-th variable frequency motor is adjusted to Vii = Vi(1+|ΔTi|).

[0102] Where ΔTi represents the load difference of the i-th variable frequency motor, Vi represents the actual speed of the i-th variable frequency motor, and Vii represents the adjustment target value of the actual speed of the i-th variable frequency motor.

[0103] When raising the platform or lowering the pile legs, the torque and rotational speed of the pinion are in the same direction. The greater the load on the pinion, the lower its rotational speed. Correspondingly, the greater the load on the variable frequency motor, the lower its rotational speed. When the load difference ΔTi > 0, it means Ti > T0, that is, the estimated load of the main motor or slave motor is greater than the theoretical load. Therefore, it is necessary to reduce the estimated load of the main motor or slave motor. In this case, the estimated load can be reduced by increasing the actual rotational speed of the main motor or slave motor. That is, when raising the platform or lowering the pile legs, the actual rotational speed of the main motor or slave motor can be increased to reduce the estimated load. When the load difference ΔTi < 0, it means Ti < T0, that is, the estimated load of the main motor or slave motor is less than the theoretical load. Therefore, it is necessary to increase the estimated load of the main motor or slave motor. In this case, the estimated load can be increased by decreasing the actual rotational speed of the main motor or slave motor. That is, when raising the platform or lowering the pile legs, the actual rotational speed of the main motor or slave motor can be decreased to increase the estimated load.

[0104] When lowering the platform or raising the legs, the torque and rotational speed of the pinion are opposite. The greater the load on the pinion, the higher its rotational speed. Correspondingly, the greater the load on the variable frequency motor, the higher its rotational speed. When the load difference ΔTi > 0, it means Ti > T0, that is, the estimated load of the slave or main motor is greater than the theoretical load. Therefore, it is necessary to reduce the estimated load of the main or slave motor. This can be achieved by reducing the actual rotational speed of the main or slave motor. In other words, when raising the legs or lowering the platform, the actual rotational speed of the main or slave motor can be reduced to decrease the estimated load. When the load difference ΔTi < 0, it means Ti < T0, that is, the estimated load of the main or slave motor is less than the theoretical load. Therefore, it is necessary to increase the estimated load of the main or slave motor. This can be achieved by increasing the actual rotational speed of the main or slave motor. In other words, when raising the platform or lowering the legs, the actual rotational speed of the main or slave motor can be increased to increase the estimated load.

[0105] When ΔTi = 0, the estimated load of the main motor or the slave motor is equal to the theoretical load, meaning there is no need to adjust the actual speed of the main motor or the slave motor.

[0106] It should be noted that the speed mentioned in the above adjustment refers to the actual speed, while the value in the issued command corresponds to the theoretical speed. Therefore, after determining the adjustment ratio, such as decreasing or increasing ΔVi, the value in the previously sent command can be decreased or increased according to the ratio of ΔVi as the command to adjust the variable frequency motor.

[0107] In this embodiment, the above control method is used to control the platform of a certain lifting system. According to the platform weight and speed control requirements of the lifting system in this embodiment, the speed value in the command of the slave motor in a certain leg of the offshore platform's control system is 7960. At this time, according to Formula 1, the theoretical speed of the motor is 995 r / min. Then, the actual speed of the slave motor is detected as 980 r / min through a rotary encoder. According to Formula 2, the estimated load of the slave motor is calculated to be 48%. The estimated load of the master motor is also 48%. It can be seen that the above control method can not only ensure the consistency of speed among the slave motors, but also achieve good load consistency. This control strategy is effective and meets the requirements of engineering applications.

[0108] In other words, the above control method couples a load balancing algorithm to the speed master-slave control. When the load on a certain variable frequency motor is large, the motor actively adjusts its speed within a certain range to reduce the load. The larger the load, the more the speed is adjusted, and the greater the load reduction, thus always maintaining the load of each variable frequency motor at a relatively balanced level. This is because the 12 variable frequency motors on each pile leg always maintain speed master-slave control. However, to maintain speed balance, an adjustment range can be set during load adjustment. Adjustment is performed within a certain threshold (e.g., 10%). If the adjustment range exceeds this threshold, the threshold value is used for adjustment.

[0109] The above scheme can achieve maximum load balancing while ensuring speed balance as much as possible.

[0110] Figure 3 is a structural block diagram of a control device for a lifting system provided in an embodiment of this disclosure. The lifting system includes multiple legs, each leg is equipped with multiple lifting units, each lifting unit includes a variable frequency motor, and the multiple variable frequency motors on each leg include a main motor and multiple slave motors. This control device can serve as all or part of the control system of an offshore platform. As shown in Figure 3, the control device 300 includes a determining module 301 and an adjusting module 302.

[0111] The determination module 301 is used to determine the parameter information of multiple variable frequency motors on any given pile leg. The parameter information includes the actual speed, estimated load, theoretical speed and theoretical load. The theoretical speeds of the multiple variable frequency motors are the same, and the theoretical loads of the multiple variable frequency motors are the same.

[0112] The adjustment module 302 is used to adjust the actual speed of multiple variable frequency motors according to the parameter information of multiple variable frequency motors, so that the difference between the actual speed and the theoretical speed of each variable frequency motor, and the difference between the estimated load and the theoretical load are all within the threshold range.

[0113] The control device has the same beneficial effects as the control method described above, and will not be described in detail here.

[0114] Optionally, the determining module 301 is used to acquire the instructions sent by the control system of the offshore platform to the main motor, the instructions including speed values; determine the theoretical speed of multiple variable frequency motors based on the speed values ​​in the instructions; acquire the actual speed of multiple variable frequency motors detected by the rotary encoder; calculate the estimated load of multiple variable frequency motors based on the theoretical speed and actual speed of multiple variable frequency motors; and determine the theoretical load of multiple variable frequency motors according to the load of the offshore platform.

[0115] Optionally, the determining module 301 is used to calculate the estimated load of the variable frequency motor using the following formula:

[0116] Where Ti is the estimated load of the i-th variable frequency motor, i≤n; n represents the number of variable frequency motors; Let be the theoretical speed of the i-th variable frequency motor; is the actual speed of the i-th variable frequency motor; r is the droop coefficient.

[0117] Optionally, the adjustment module 302 is used to calculate the speed difference between the actual speed and the theoretical speed of the multiple variable frequency motors, and to calculate the load difference between the estimated load and the theoretical load of the multiple variable frequency motors; when the absolute value of the speed difference of any variable frequency motor is greater than the speed threshold, and / or when the absolute value of the load difference of any variable frequency motor is greater than the load threshold, the actual speed of at least one of the multiple variable frequency motors is adjusted until the absolute value of the speed difference of all variable frequency motors is not greater than the speed threshold, and the absolute value of the load difference of all variable frequency motors is not greater than the load threshold.

[0118] Optionally, the adjustment module 302 is used to calculate the speed difference between the actual speed and the theoretical speed of the variable frequency motor according to the following formula:

[0119] Where ΔVi represents the difference between the actual speed and the theoretical speed of the i-th variable frequency motor, i≤n; n represents the number of variable frequency motors; Vi represents the actual speed of the i-th variable frequency motor; and V0 represents the theoretical speed.

[0120] Optionally, the adjustment module 302 is used to calculate the load difference between the estimated load and the theoretical load of the variable frequency motor according to the following formula:

[0121] Where ΔTi represents the load difference between the estimated load and the theoretical load of the i-th variable frequency motor, i≤n; n represents the number of variable frequency motors; Ti represents the estimated load of the i-th variable frequency motor; and T0 represents the theoretical load.

[0122] Optionally, the adjustment module 302 is used to adjust the actual speed of the i-th variable frequency motor to Vii = Vi(1-|ΔVi|) when the speed difference ΔVi of the i-th variable frequency motor is greater than 0.

[0123] Alternatively, when the speed difference ΔVi of the i-th variable frequency motor is less than 0, the actual speed of the i-th variable frequency motor is adjusted to Vii = Vi(1 + |ΔVi|).

[0124] Where ΔVi represents the speed difference of the i-th variable frequency motor, Vi represents the actual speed of the i-th variable frequency motor, and Vii represents the adjustment target value of the actual speed of the i-th variable frequency motor.

[0125] Optionally, the adjustment module 302 is used to adjust the actual speed of the i-th variable frequency motor to Vii = Vi(1 + |ΔTi|) when the lifting system is in the lifting platform mode or the lowering pile leg mode, and the load difference ΔTi of the i-th variable frequency motor is greater than 0; or, when the lifting system is in the lifting platform mode or the lowering pile leg mode, and the load difference ΔTi of the i-th variable frequency motor is less than 0, the actual speed of the i-th variable frequency motor is adjusted to Vii = Vi(1 - |ΔTi|).

[0126] When the lifting system is in the lowering platform mode or the raising leg mode, and the load difference ΔTi of the i-th variable frequency motor is greater than 0, the actual speed of the i-th variable frequency motor is adjusted to Vii = Vi(1-|ΔTi|); or, when the lifting system is in the lowering platform mode or the raising leg mode, and the load difference ΔTi of the i-th variable frequency motor is less than 0, the actual speed of the i-th variable frequency motor is adjusted to Vii = Vi(1+|ΔTi|).

[0127] Where ΔTi represents the load difference of the i-th variable frequency motor, Vi represents the actual speed of the i-th variable frequency motor, and Vii represents the adjustment target value of the actual speed of the i-th variable frequency motor.

[0128] It should be noted that the control device 300 provided in the above embodiments is only illustrated by the division of the above functional modules when controlling the lifting system. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the equipment can be divided into different functional modules to complete all or part of the functions described above. In addition, the control device 300 provided in the above embodiments and the control method embodiments belong to the same concept, and its specific implementation process can be found in the method embodiments, which will not be repeated here.

[0129] Figure 4 is a structural block diagram of a computer device provided in an embodiment of this disclosure. As shown in Figure 4, the computer device 400 may be a computer or the like, and may serve as all or part of the control system of an offshore platform. The computer device 400 includes a processor 401 and a memory 402.

[0130] Processor 401 may include one or more processing cores, such as a quad-core processor, an octa-core processor, etc. Processor 401 may be implemented using at least one hardware form selected from DSP (Digital Signal Processing), FPGA (Field-Programmable Gate Array), and PLA (Programmable Logic Array). Processor 401 may also include a main processor and a coprocessor. The main processor, also known as a CPU (Central Processing Unit), is used to process data in the wake-up state; the coprocessor is a low-power processor used to process data in the standby state. In some embodiments, processor 401 may integrate a GPU (Graphics Processing Unit), which is responsible for rendering and drawing the content to be displayed on the screen. In some embodiments, processor 401 may also include an AI (Artificial Intelligence) processor, which is used to handle computational operations related to machine learning.

[0131] The memory 402 may include one or more computer-readable media, which may be non-transitory. The memory 402 may also include high-speed random access memory and non-volatile memory, such as one or more disk storage devices or flash memory devices. In some embodiments, the non-transitory computer-readable media in the memory 402 is used to store at least one instruction, which is executed by the processor 401 to implement the control method provided in the embodiments of this disclosure.

[0132] Those skilled in the art will understand that the structure shown in FIG4 does not constitute a limitation on the computer device 400, and may include more or fewer components than shown, or combine certain components, or employ different component arrangements.

[0133] This disclosure also provides a computer storage medium storing computer instructions. When the computer instructions stored in the computer-readable storage medium are executed by an electronic device, the electronic device performs the control method of the lifting system provided in the above-described method embodiments.

[0134] This disclosure also provides a computer program product, which includes one or more computer program instructions. When the computer program instructions are loaded and run by a computer, the computer executes the control method for the lifting system provided in the above-described method embodiments.

[0135] The above description is merely an optional embodiment of this disclosure and is not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A control method for a lifting system, the lifting system comprising multiple legs, each leg having multiple lifting units, each lifting unit comprising a variable frequency motor, the multiple variable frequency motors on each leg comprising a main motor and multiple slave motors, the control method comprising: For any of the pile legs, the parameter information of the plurality of variable frequency motors on the pile leg is determined. The parameter information includes the actual speed, estimated load, theoretical speed and theoretical load. The theoretical speed of the plurality of variable frequency motors is the same, and the theoretical load of the plurality of variable frequency motors is the same. Based on the parameter information of the multiple variable frequency motors, the actual speeds of the multiple variable frequency motors are adjusted so that the difference between the actual speed and the theoretical speed of each variable frequency motor, and the difference between the estimated load and the theoretical load, are all within the threshold range.

2. The control method according to claim 1, wherein, Determine the parameter information of the plurality of variable frequency motors on the pile legs, including: The system receives commands sent from the control system of the offshore platform to the main motor, the commands including speed values. Based on the speed value in the instruction, the theoretical speed of the plurality of variable frequency motors is determined; Obtain the actual rotational speed of the plurality of variable frequency motors detected by the rotary encoder; Based on the theoretical and actual speeds of the multiple variable frequency motors, the estimated load of the multiple variable frequency motors is calculated; The theoretical load of the multiple variable frequency motors is determined based on the load capacity of the offshore platform.

3. The control method according to claim 2, wherein, Based on the theoretical and actual speeds of the multiple variable frequency motors, the estimated load of the multiple variable frequency motors is calculated, including: The estimated load of the variable frequency motor is calculated using the following formula: Where Ti is the estimated load of the i-th variable frequency motor, i≤n; n represents the number of variable frequency motors; Let be the theoretical speed of the i-th variable frequency motor; is the actual speed of the i-th variable frequency motor; r is the droop coefficient.

4. The control method according to any one of claims 1 to 3, wherein, Based on the parameter information of the plurality of variable frequency motors, the actual speeds of the plurality of variable frequency motors are adjusted respectively, including: Calculate the speed difference between the actual speed and the theoretical speed of the multiple variable frequency motors, and calculate the load difference between the actual load and the theoretical load of the multiple variable frequency motors. If the absolute value of the speed difference of any of the variable frequency motors is greater than the speed threshold, and / or if the absolute value of the load difference of any of the variable frequency motors is greater than the load threshold, adjust the actual speed of at least one of the plurality of variable frequency motors until the absolute value of the speed difference of all the variable frequency motors is not greater than the speed threshold, and the absolute value of the load difference of all the variable frequency motors is not greater than the load threshold.

5. The control method according to claim 4, wherein, Calculate the speed difference between the actual speed and the theoretical speed of the plurality of variable frequency motors, including: The speed difference between the actual speed and the theoretical speed of the variable frequency motor is calculated using the following formula: Where ΔVi represents the difference between the actual speed and the theoretical speed of the i-th variable frequency motor, i≤n; n represents the number of variable frequency motors; Vi represents the actual speed of the i-th variable frequency motor; V0 represents the theoretical speed.

6. The control method according to claim 4, wherein, Calculate the load difference between the estimated load and the theoretical load of the plurality of variable frequency motors, including: The load difference between the estimated load and the theoretical load of the variable frequency motor is calculated using the following formula: Where ΔTi represents the load difference between the estimated load and the theoretical load of the i-th variable frequency motor, i≤n; n represents the number of variable frequency motors; Ti represents the estimated load of the i-th variable frequency motor; and T0 represents the theoretical load.

7. The control method according to any one of claims 4 to 6, wherein, Adjusting the actual speed of at least one of the plurality of variable frequency motors includes: When the speed difference ΔVi of the i-th variable frequency motor is greater than 0, the actual speed of the i-th variable frequency motor is adjusted to Vii = Vi(1-|ΔVi|); Alternatively, when the speed difference ΔVi of the i-th variable frequency motor is less than 0, the actual speed of the i-th variable frequency motor is adjusted to Vii = Vi(1 + |ΔVi|). Wherein, ΔVi represents the speed difference of the i-th variable frequency motor, Vi represents the actual speed of the i-th variable frequency motor, and Vii represents the adjustment target value of the actual speed of the i-th variable frequency motor.

8. The control method according to claim 7, wherein, Adjusting the actual speed of at least one of the plurality of variable frequency motors further includes: When the lifting system is in the platform raising or pile leg lowering mode, and the load difference ΔTi of the i-th variable frequency motor is greater than 0, the actual speed of the i-th variable frequency motor is adjusted to Vii = Vi(1 + |ΔTi|); or, when the lifting system is in the platform raising or pile leg lowering mode, and the load difference ΔTi of the i-th variable frequency motor is less than 0, the actual speed of the i-th variable frequency motor is adjusted to Vii = Vi(1 - |ΔTi|). When the lifting system is in the lowering platform mode or the raising leg mode, and the load difference ΔTi of the i-th variable frequency motor is greater than 0, the actual speed of the i-th variable frequency motor is adjusted to Vii = Vi(1-|ΔTi|); or, when the lifting system is in the lowering platform mode or the raising leg mode, and the load difference ΔTi of the i-th variable frequency motor is less than 0, the actual speed of the i-th variable frequency motor is adjusted to Vii = Vi(1+|ΔTi|). Wherein, ΔTi represents the load difference of the i-th variable frequency motor, Vi represents the actual speed of the i-th variable frequency motor, and Vii represents the adjustment target value of the actual speed of the i-th variable frequency motor.

9. A control device for a lifting system, the lifting system comprising multiple legs, each leg being provided with multiple lifting units, each lifting unit comprising a variable frequency motor, the multiple variable frequency motors on each leg comprising a main motor and multiple slave motors, the control device comprising a determining module and an adjusting module; The determining module is used to determine the parameter information of the plurality of variable frequency motors on any one of the pile legs. The parameter information includes the actual speed, estimated load, theoretical speed and theoretical load. The theoretical speed of the plurality of variable frequency motors is the same, and the theoretical load of the plurality of variable frequency motors is the same. The adjustment module is used to adjust the actual speed of the multiple variable frequency motors according to the parameter information of the multiple variable frequency motors, so that the difference between the actual speed and the theoretical speed of each variable frequency motor, and the difference between the estimated load and the theoretical load, are all within the threshold range.

10. A computer device, wherein, The computer device includes a processor and a memory configured to store executable instructions of the processor; the processor is configured to perform the control method of the lifting system according to any one of claims 1 to 8.

11. A computer storage medium having computer instructions stored thereon, wherein, When the computer instructions are executed by the processor, they implement the control method of the lifting system according to any one of claims 1 to 8.

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