Energy-saving and consumption-reducing control method and system for underground belt conveyor with multi-stage frequency conversion drive

Abstract

A multi-stage variable frequency drive underground belt conveyor energy-saving and consumption-reduction control method and system are described. The method involves obtaining coal flow rate data and conveyor belt operating speed data based on the coal flow weight signal and operating speed signal, and performing filtering processing. A type-two fuzzy set of input parameters is abstracted and constructed. The belt conveyor is started and multi-stage precise control is performed on the belt conveyor using a two-degree-of-freedom PID controller and type-two fuzzy sets. The system includes a coal flow rate monitoring sensor installed on the belt conveyor; a speed sensor installed on the drive roller; a composite frequency conversion unit comprising a main frequency conversion unit, auxiliary frequency conversion units one and two; the main frequency conversion unit comprising a connected main frequency converter and main motor; and an auxiliary frequency conversion unit comprising a connected auxiliary frequency converter and auxiliary motor. A controller is connected to the coal flow rate monitoring sensor, speed sensor, composite frequency conversion unit, and a human-machine interface. This method and system achieve multi-stage precise control of the belt conveyor's operating speed, achieving ideal energy-saving results.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy-saving intelligent control of belt conveyors, and in particular relates to an energy-saving and consumption-reducing control method and system for a multi-stage frequency conversion driven underground belt conveyor. Background Art

[0002] In underground coal mines, belt conveyors are the primary transportation equipment, responsible for transporting coal and other materials. However, traditional underground belt conveyors have many problems that seriously affect energy efficiency and production benefits.

[0003] On the one hand, most belt conveyors currently operate in a single-frequency mode. In actual production, the coal flow rate is constantly changing, but the conveyor speed cannot be adjusted in real time. When the coal flow rate is low, the conveyor still runs at a fixed high speed, resulting in a large amount of electricity waste, which invisibly increases the production cost of the coal mine. On the other hand, when starting, existing belt conveyors are often started directly or using a simple starting method. This will generate a large starting current, which not only impacts the power grid and affects the stability of the power grid, but also accelerates the mechanical wear of the equipment and shortens the service life of the equipment. In addition, the existing belt conveyor control system has a low level of intelligence, making it difficult to achieve precise energy-saving control based on complex operating conditions and changes in coal flow, and cannot meet the needs of modern coal mines for efficient and energy-saving production.

[0004] Therefore, there is an urgent need to provide an energy-saving and consumption-reducing control method and system for an underground belt conveyor with a multi-stage variable frequency drive that can meet the needs of efficient and energy-saving production in modern coal mines. Summary of the Invention

[0005] In response to the problems existing in the above-mentioned prior art, the present invention provides a multi-stage frequency conversion driven underground belt conveyor energy-saving and consumption-reduction control method and system. The method has low implementation cost, high intelligence and ideal energy-saving effect. It can adjust the working mode of multiple frequency converters in real time according to the coal flow rate, and can intelligently adjust the running speed of the conveyor belt based on the matching technology of belt speed and coal flow rate. At the same time, it has good starting characteristics, which is conducive to extending the service life of the conveying equipment; the system has a simple structure, low manufacturing cost and ideal energy-saving effect. It can intelligently select the working combination mode of multiple frequency converters in the composite frequency conversion unit according to the load conditions, and at the same time, it can realize multi-stage precise control of the running speed of the belt conveyor.

[0006] In order to achieve the above object, the present invention provides an energy-saving and consumption-reducing control method for a multi-stage variable frequency driven underground belt conveyor, comprising the following steps:

[0007] Step 1: Install the coal flow monitoring sensor on the belt conveyor and the speed sensor on the driving roller of the belt conveyor;

[0008] Step 2: During the operation of the belt conveyor, the coal flow monitoring sensor is used to collect the coal flow weight signal on the conveyor belt in real time and send it to the signal processing module. The speed sensor is used to collect the running speed signal of the driving roller in real time and send it to the signal processing module. The signal processing module amplifies and denoises the coal flow weight signal and the running speed signal and sends them to the controller.

[0009] Step 3: The controller obtains the coal flow data and the conveyor belt running speed data according to the coal flow weight signal and the running speed signal, and performs filtering processing to obtain high-precision monitoring data;

[0010] Step 4: Abstract and construct type-2 fuzzy sets of input parameters;

[0011] The speed of the conveyor belt The domain is set as follows: 0< <0.9 corresponds to the ultra-low speed state T, and 0.9≤ <1.7 corresponds to the medium and low speed state TM, and 1.7≤ <2.5 corresponds to the medium speed state M, and 2.5≤ <3.3 corresponds to the medium and high speed state Q, and 3.3≤ ≤4.5 corresponds to the maximum speed state QA;

[0012] The coal flow The domain is set as follows: 0≤ <20 corresponds to low flow state LL, 20≤ <40 corresponds to the low to medium flow state L, and 40≤ <60 corresponds to the medium flow state M, and 60≤ <80 corresponds to the medium and high flow state HM, and 80≤ ≤100 corresponds to full load flow state H;

[0013] Set the output matching degree as follows: -2 corresponds to a 2-speed reduction, -1 corresponds to a 1-speed reduction, 0 corresponds to maintaining the current speed, 1 corresponds to a 1-speed increase, and 2 corresponds to a 2-speed increase.

[0014] Step 5: Start the belt conveyor and perform multi-level precise control on the belt conveyor by combining two-degree-of-freedom PID and type-two fuzzy sets;

[0015] When the belt conveyor starts, the controller sends a specific start-up control signal to the composite frequency conversion unit, so that the composite frequency conversion unit gradually and slowly increases the frequency and voltage according to the preset start-up curve;

[0016] When 0≤ When the value is less than 20, the controller controls the composite frequency conversion unit to stop completely and enter the shutdown mode;

[0017] When 20≤ When the value is less than 40, the controller controls the main frequency conversion unit to operate;

[0018] When 40≤ When the value is less than 60, the controller controls the main frequency conversion unit and the auxiliary frequency conversion unit to run simultaneously;

[0019] When 60≤ When the value is less than 80, the controller controls the main frequency conversion unit, auxiliary frequency conversion unit 1 and auxiliary frequency conversion unit 2 to run simultaneously;

[0020] When 80≤ When ≤100, the controller controls the main frequency conversion unit, auxiliary frequency conversion unit 1 and auxiliary frequency conversion unit 2 to run simultaneously.

[0021] In order to obtain more accurate data, in step three, the specific process of obtaining high-precision monitoring data is as follows:

[0022] S31: Combining the kinematic characteristics of the belt conveyor with the layout of the coal flow monitoring sensor and speed sensor, the state vector is defined according to formula (1): ;

[0023] (1);

[0024] Where, For conveyor belt The running speed data at the moment, For conveyor belt The load at the moment, is the transpose operation;

[0025] S32: Establish a state equation based on the belt conveyor motion model according to formula (2); establish an observation equation based on the belt conveyor motion model according to formula (3);

[0026] (2);

[0027] Where, for The state of the moment; for The state of the moment; is the state transition matrix, , is the sampling time interval, is the friction coefficient of the conveyor belt, for Motor current at the moment; is the control input matrix, , is the equivalent mass of the conveyor belt; is the motor torque control quantity; is the process noise;

[0028] (3);

[0029] Where, for The measured value of the sensor at each moment; is the observation matrix, , Calibrate the system for load cells; is the observation noise;

[0030] S33: Continuously modify the state scheme through the observation equation and use the Kalman gain Recursively update the state estimate and covariance matrix to output high-precision monitoring data.

[0031] In order to dynamically adjust the motor with high precision, in step five, the controller controls the inverter in the composite inverter unit through the following process:

[0032] S51: establishing a belt speed and coal flow matching model according to formula (4), and obtaining a given speed value of the conveyor belt for the next cycle based on the belt speed and coal flow matching model;

[0033] (4);

[0034] Where, is the matching degree between the conveyor belt running speed data and the coal flow data, represents a type-one fuzzy set, where , is the number of inference rules; , represents r input data;

[0035] S52: Convert the conveyor belt speed curve into the motor speed desired curve according to formula (5), and obtain the motor desired speed value based on formula (5) ;

[0036] (5);

[0037] Where, Indicates the efficiency factor of the reducer or the loss caused by gear wear. Indicates the maximum speed of the conveyor belt. Indicates the maximum motor speed; Indicates the speed of a given conveyor belt;

[0038] S53: Obtain the acceleration of the motor's desired speed curve according to formula (6) ;

[0039] (6);

[0040] Where, Indicates the current speed of the motor; Indicates the acceleration and deceleration time of the belt conveyor;

[0041] S54: Combine the two-degree-of-freedom PID and type-II fuzzy control methods to intercept the motor's desired speed curve line segment at equal intervals, calculate the speed difference between the motor's desired speed and the current motor speed based on the desired speed, and calculate the approximate acceleration of the line segment at the same time, using the parameter , Amplify the speed difference and acceleration, and then use the amplified speed difference and acceleration as input data to output a proportional coefficient for adjusting the two-degree-of-freedom PID. and Parameters, according to the speed-adjusted parameters, output the speed compensation amount, and then get the final target speed based on the sum of the current speed and the speed compensation amount;

[0042] S55: Convert the final target speed into the inverter frequency in proportion according to formula (7) ;

[0043] (7);

[0044] Where, is the final target speed of the motor, p is the number of pole pairs of the motor, is the power frequency;

[0045] S56: According to the principle of DA conversion inside the inverter to control the inverter, the video is converted into digital information and the speed setting value is obtained according to formula (8) , and output the speed setting value To the inverter;

[0046] (8);

[0047] Where, Indicates the reference speed of the motor, and n is the number of bits of the DA conversion control inverter.

[0048] The present invention provides an energy-saving and consumption-reducing control method for a multi-stage variable-frequency-driven underground belt conveyor. This method addresses the problems of severe energy waste, high starting current, and low intelligence level associated with conventional underground belt conveyors, as identified in the aforementioned background art. The present invention's technical solution enables the belt conveyor to adjust its operating speed in real time based on coal flow, reducing energy consumption. This method also minimizes the impact of starting current on the power grid and equipment, improving the intelligent control level of conveying equipment, and thereby significantly reducing coal mine production costs and improving production efficiency.

[0049] Compared with the prior art, the present invention has the following advantages:

[0050] 1. Significant energy savings: The coordinated operation of coal flow monitoring sensors and controllers allows precise adjustment of belt conveyor speed based on real-time changes in coal flow. This reduces speed when coal flow is low, avoiding energy waste caused by high-speed idling. Extensive field testing has demonstrated a 30%-40% reduction in energy consumption, significantly lowering coal mine production costs.

[0051] 2. Reduced starting current surge: During startup, the composite frequency conversion unit gradually increases frequency and voltage according to a preset startup curve, achieving a soft start for the belt conveyor. This significantly reduces starting current, lowering the impact on the power grid by approximately 70%-80%. It also reduces mechanical wear on the conveying equipment, extending its service life and lowering maintenance costs.

[0052] 3. Improved Intelligent Control: The controller provides intelligent control of the belt conveyor based on pre-set control strategies and algorithms. Furthermore, the human-machine interface facilitates operator parameter setting and operational status monitoring, improving the convenience and efficiency of production management. This makes the belt conveyor's operation more stable and reliable, enabling it to better adapt to the complex and ever-changing underground production environment.

[0053] This method has low implementation cost, high intelligence and ideal energy-saving effect. It can adjust the working mode of multiple frequency converters in real time according to the coal flow rate, and can intelligently adjust the running speed of the conveyor belt based on the matching technology of belt speed and coal flow rate. At the same time, it has good starting characteristics, which is conducive to extending the service life of the conveying equipment.

[0054] The present invention also provides a multi-stage frequency conversion drive underground belt conveyor energy-saving and consumption-reduction control system, which is used to implement a multi-stage frequency conversion drive underground belt conveyor energy-saving and consumption-reduction control method, including a coal flow monitoring sensor, a speed sensor, a composite frequency conversion unit, a human-computer interaction interface and a controller;

[0055] The coal flow monitoring sensor is a high-precision electronic belt scale, which is installed on the belt conveyor and is used to collect the coal flow weight signal on the conveyor belt in real time;

[0056] The speed sensor is installed on the driving roller of the belt conveyor and is used to collect the running speed signal of the driving roller in real time;

[0057] The composite frequency conversion unit includes a main frequency conversion unit, an auxiliary frequency conversion unit 1 and an auxiliary frequency conversion unit 2. The main frequency conversion unit includes a main frequency converter and a main motor connected to each other; the auxiliary frequency conversion unit 1 includes an auxiliary frequency converter 1 and an auxiliary motor 1 connected to each other; the auxiliary frequency conversion unit 2 includes an auxiliary frequency converter 2 and an auxiliary motor 2 connected to each other; the main motor, the auxiliary motor 1 and the auxiliary motor 2 are all connected to the transmission shaft of the drive drum through a reducer;

[0058] The controller is connected to the coal flow monitoring sensor, the speed sensor and the composite frequency conversion unit respectively, and is used to obtain coal flow data and conveyor belt running speed data based on the coal flow weight signal and the running speed signal, and send corresponding control signals to the composite frequency conversion unit based on the coal flow data and the conveyor belt running speed data, thereby realizing intelligent control of the belt conveyor;

[0059] The human-machine interaction interface is connected to the controller and is used to provide a human-machine interaction interface. At the same time, it is used to display coal flow data, operating speed data, and the operating status of the composite frequency conversion unit.

[0060] Furthermore, in order to facilitate timely execution of warning actions when an abnormality occurs to effectively remind relevant personnel, an audible and visual alarm module is also included. The audible and visual alarm module is installed on the belt conveyor and connected to the controller.

[0061] As a preference, the speed sensor adopts a rotary encoder, and the human-computer interaction interface adopts a touch screen.

[0062] Furthermore, in order to facilitate signal amplification and filtering, a signal processing module is also included, and the controller is connected to the coal flow monitoring sensor and the speed sensor through the signal processing module.

[0063] Furthermore, in order to facilitate real-time perception of the speed data of each motor, the main motor is equipped with a motor speed sensor 1, the auxiliary motor 1 is equipped with a motor speed sensor 2, and the auxiliary motor 2 is equipped with a motor speed sensor 3.

[0064] As a preference, the controller is a PLC controller.

[0065] In the present invention, the provision of a coal flow monitoring sensor facilitates real-time acquisition of coal flow weight signals during belt conveyor conveying operations, thereby enabling the controller to sense coal flow data on the conveyor belt in real time. Connecting a speed sensor to the drive roller facilitates real-time acquisition of the drive roller's operating speed signal during belt conveyor conveying operations, thereby enabling the controller to calculate the conveyor belt's operating speed data based on the drive roller's operating speed data. The composite frequency conversion unit comprises a main frequency conversion unit, a first auxiliary frequency conversion unit, and a second auxiliary frequency conversion unit. This innovatively employs a coordinated operation architecture of a main frequency converter and two slave frequency converters in the belt conveyor. Consequently, when the load is low, only the main frequency converter operates; when the load is medium, the main frequency converter and the first auxiliary frequency converter operate in conjunction; and when the load is high, the main frequency converter and the two auxiliary frequency converters operate together. This allows different combinations of drive force to be provided according to different loads, effectively saving energy consumption and achieving multi-level precise control of the belt conveyor's operating speed. Through the setting of the human-computer interaction interface, not only can relevant personnel observe the operating status of the belt conveyor in real time, but also relevant personnel can adjust and optimize parameters such as the coal flow threshold and speed adjustment range through the human-computer interaction interface according to actual production conditions and long-term experience accumulation, so that the control system can better adapt to different working conditions and production needs.

[0066] The system has a simple structure, low manufacturing cost and ideal energy-saving effect. It can intelligently select the working combination mode of multiple inverters in the composite frequency conversion unit according to the load conditions, which can effectively save energy consumption. At the same time, it can achieve multi-level precise control of the belt conveyor's operating speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 This is a workflow diagram of the control method part of the present invention;

[0068] Figure 2 This is a principle block diagram of the control system part of the present invention;

[0069] Figure 3 is a flow chart of the control algorithm of the present invention;

[0070] Figure 4 This is a schematic diagram of the assembly of the control system of the present invention on the belt conveyor;

[0071] Figure 5 Schematic diagram of the dual-loop control process in the present invention. DETAILED DESCRIPTION

[0072] The present invention will be further described below with reference to the accompanying drawings.

[0073] like Figures 1 to 5As shown, the present invention provides an energy-saving and consumption-reducing control method for a multi-stage frequency conversion driven underground belt conveyor, which adopts an energy-saving and consumption-reducing control system for a multi-stage frequency conversion driven underground belt conveyor, comprising the following steps:

[0074] Step 1: Install the coal flow monitoring sensor on the belt conveyor and the speed sensor on the driving roller of the belt conveyor;

[0075] Step 2: During the operation of the belt conveyor, the coal flow monitoring sensor is used to collect the coal flow weight signal on the conveyor belt in real time and send it to the signal processing module. The speed sensor is used to collect the running speed signal of the driving roller in real time and send it to the signal processing module. The signal processing module amplifies and denoises the coal flow weight signal and the running speed signal and sends them to the controller.

[0076] Step 3: The controller obtains the coal flow data and the conveyor belt running speed data according to the coal flow weight signal and the running speed signal, and performs filtering processing to obtain high-precision monitoring data;

[0077] In order to obtain data with higher accuracy, the specific process of obtaining high-precision monitoring data is as follows:

[0078] S31: Combining the kinematic characteristics of the belt conveyor with the layout of the coal flow monitoring sensor and speed sensor, the state vector is defined according to formula (1): ;

[0079] (1);

[0080] Where, For conveyor belt The running speed data at the moment, For conveyor belt The load at the moment, is the transpose operation;

[0081] S32: Establish a state equation based on the belt conveyor motion model according to formula (2); establish an observation equation based on the belt conveyor motion model according to formula (3);

[0082] (2);

[0083] Where, for The state of the moment; for The state of the moment; is the state transition matrix, , is the sampling time interval, is the friction coefficient of the conveyor belt, for Motor current at the moment; is the control input matrix, , is the equivalent mass of the conveyor belt; is the motor torque control quantity; is the process noise;

[0084] (3);

[0085] Where, for The measured value of the sensor at each moment; is the observation matrix, , Calibrate the system for load cells; is the observation noise;

[0086] S33: Continuously modify the state scheme through the observation equation and use the Kalman gain Recursively update the state estimate and covariance matrix to output high-precision monitoring data. Among them, the Kalman gain The calculation of and the update of the state estimate and covariance matrix follow the standard algorithm flow of the Kalman filter.

[0087] Step 4: Abstract and construct type-2 fuzzy sets of input parameters;

[0088] The speed of the conveyor belt The domain is set as follows: 0< <0.9 corresponds to the ultra-low speed state T, and 0.9≤ <1.7 corresponds to the medium and low speed state TM, and 1.7≤ <2.5 corresponds to the medium speed state M, and 2.5≤ <3.3 corresponds to the medium and high speed state Q, and 3.3≤ ≤4.5 corresponds to the maximum speed state QA;

[0089] The coal flow The domain is set as follows: 0≤ <20 corresponds to low flow state LL (very low load), and 20≤ <40 corresponds to medium to low flow state L (medium to low load), and 40≤ <60 corresponds to the medium flow state M (medium load), and 60≤ <80 corresponds to the medium to high flow state HM (medium to high load), and 80≤ ≤100 corresponds to full load flow state H (high load);

[0090] Set the operating modes as follows: shutdown mode (0Hz, applicable when the coal flow rate is 0 or below the minimum threshold), level 1 operating mode (low load, greater than 0 and less than 20Hz, only the main inverter operates, suitable for medium to low coal flow conditions), level 2 operating mode (medium to low load, greater than 20 and less than 35Hz, the main inverter and auxiliary inverter 1 work together, suitable for medium coal flow conditions), level 3 operating mode (medium to high load, greater than 35 and less than 45Hz, the main inverter, auxiliary inverter 1, and auxiliary inverter 2 operate together, suitable for medium to high coal flow conditions), level 4 operating mode (high load, greater than or equal to 45 and less than or equal to 60Hz, the main inverter, auxiliary inverter 1, and auxiliary inverter 2 operate together and output full power, suitable for full load or peak coal flow conditions).

[0091] Based on the belt speed coal flow matching technology, the belt speed coal flow matching degree is output as the output parameter variable. Specifically, the output matching degree is set as follows: -2 corresponds to a speed reduction of 2 gears (E), -1 corresponds to a speed reduction of 1 gear (LE), 0 corresponds to maintaining the current speed (S), 1 corresponds to a speed increase of 1 gear (LF), and 2 corresponds to a speed increase of 2 gears (F);

[0092] The fuzzy rules obtained based on the above process are shown in Table 1;

[0093] Table 1: Fuzzy rules table

[0094]

[0095] Step 5: Start the belt conveyor and perform multi-level precise control on the belt conveyor by combining two-degree-of-freedom PID and type-two fuzzy sets;

[0096] When the belt conveyor starts, the controller sends a specific startup control signal to the composite frequency conversion unit, causing it to gradually and slowly increase the frequency and voltage according to the preset startup curve. During the startup process, the frequency increase rate is intelligently and precisely adjusted according to the belt conveyor load (coal flow rate). The greater the load, the slower the frequency increase rate, thus achieving a soft start for the belt conveyor, effectively reducing the impact of the startup current on the power grid and mechanical wear on the equipment. At the same time, operators can flexibly and conveniently adjust and optimize parameters such as the coal flow threshold and speed adjustment range through the human-machine interface based on actual production conditions and experience, allowing the control device and control method to better adapt to different operating conditions and production needs.

[0097] When 0≤ When the value is less than 20, the coal flow rate is 0 or lower than the minimum threshold, and the controller controls the composite frequency conversion unit to stop completely and enter the shutdown mode, so that the system stops completely to avoid the occurrence of no-load loss. In the shutdown mode, the operating frequency of each inverter in the composite frequency conversion unit is 0Hz.

[0098] When 20≤ <40, the controller controls the main frequency conversion unit to operate, 0<working frequency<20 Hz, in the first-level working mode, which can be applied to medium and low flow conditions; at the same time, when 0< <0.9, maintain the current speed unchanged, when 0.9≤ <1.7, increase the speed by 1 gear based on the current speed. When 1.7≤ <2.5, reduce the speed by 2 gears based on the current speed. When 2.5≤ <3.3, reduce the speed by 2 gears based on the current speed. When 3.3≤ When the speed is ≤4.5, the speed is reduced by 2 gears based on the current speed; in the first-level working mode, the operating frequency range of the main inverter in the composite frequency conversion unit is greater than 0 and less than 20Hz;

[0099] When 40≤ <60, the controller controls the main frequency conversion unit and the auxiliary frequency conversion unit to run simultaneously, 20≤ working frequency<35 Hz, in the secondary working mode, suitable for medium flow conditions; at the same time, when 0< <0.9, increase the speed by 1 gear based on the current speed. When 0.9≤ <1.7, maintain the current speed unchanged, when 1.7≤ <2.5, reduce the speed by one gear based on the current speed. When 2.5≤ <3.3, reduce the speed by 2 gears based on the current speed. When 3.3≤ When the speed is ≤4.5, the speed is reduced by 2 gears based on the current speed; in the secondary working mode, the operating frequency range of the main inverter and auxiliary inverter in the composite frequency conversion unit is greater than or equal to 20 and less than 35Hz;

[0100] When 60≤ <80, the controller controls the main frequency conversion unit, auxiliary frequency conversion unit 1 and auxiliary frequency conversion unit 2 to run simultaneously, 35≤ working frequency<45 Hz, in the third-level working mode, suitable for medium and high flow conditions; at the same time, when 0< <0.9, increase the speed by 1 gear based on the current speed. When 0.9≤ <1.7, increase the speed by 1 gear based on the current speed. When 1.7≤ When <2.5, maintain the current speed. When 2.5≤ <3.3, reduce the speed by one gear based on the current speed. When 3.3≤ When the speed is ≤4.5, the speed is reduced by one gear based on the current speed. In the three-level working mode, the operating frequency range of the main inverter, auxiliary inverter 1 and auxiliary inverter 2 in the compound frequency conversion unit is greater than or equal to 35 and less than 45Hz.

[0101] When 80≤ When ≤100, the controller controls the main frequency conversion unit, auxiliary frequency conversion unit 1 and auxiliary frequency conversion unit 2 to run simultaneously, 45≤ operating frequency≤60 Hz, in the fourth-level working mode, suitable for high-flow conditions. At this time, it is full load or peak coal flow state, and the three frequency converters are full power output; at the same time, when 0< <0.9, increase 2 speeds based on the current speed. When 0.9≤ <1.7, increase 2 speeds based on the current speed. When 1.7≤ <2.5, increase 2 speeds based on the current speed. When 2.5≤ <3.3, increase the speed by 1 gear based on the current speed. When 3.3≤ When ≤4.5, the current speed is maintained unchanged. In the four-level working mode, the operating frequency range of the main inverter, auxiliary inverter 1 and auxiliary inverter 2 in the composite frequency conversion unit is greater than or equal to 45 and less than or equal to 60Hz;

[0102] In order to be able to perform high-precision dynamic adjustment of the motor, a variable frequency speed control design is carried out, such as Figure 5 As shown in the figure, based on a dual-loop cascade PID controller, an outer belt conveyor speed control loop and an inner motor speed control loop are designed. This design includes a master-slave control method for matching belt speed and coal flow to determine the desired belt conveyor speed and position, and a PID-based motor speed control device. For the speed controller, the outer loop of the dual-loop PID controller is the belt speed. The input is the difference between the desired and actual belt speeds, which determines the set speed value for the next cycle. The inner loop is the motor speed control loop. The input is the current motor speed and the set new motor speed difference. The output is a motor speed control curve, which is converted into a discretized frequency parameter and then output to the frequency converter. Because the coal flow rate transported by the belt conveyor is time-varying and unpredictable, and the belt conveyor's complex mechanical structure involves mechanical, electrical, and control components, it is difficult to establish a mathematical model. Therefore, solving the speed regulation problem using mathematical modeling is somewhat difficult. Therefore, the variable frequency speed control method for the belt conveyor is proposed to be implemented using the robust and simple PID algorithm.

[0103] The outer belt speed algorithm shows a nearly linear relationship between belt conveyor speed and motor speed when external factors such as equipment aging are minimal. Therefore, ideally, a given motor speed can be obtained by combining a given belt speed with a P controller. This given belt speed can be obtained using a belt speed and coal flow matching model. The outer loop determines the variable motor speed, while the inner loop serves as the motor speed control loop, aiming to control the motor speed to achieve the desired speed as smoothly as possible in an S-curve manner. The belt speed and coal flow matching algorithm matches a single belt speed to all load conditions within a load factor interval. Considering the constant load characteristics of a belt conveyor, it is known that within a certain load interval, a slightly lower load may result in a slightly higher motor output speed. This speed regulation is beneficial to the healthy operation of the belt conveyor. Therefore, it is acceptable for the speed control module to output a belt speed slightly higher than the desired speed curve. Furthermore, since the speed regulation strategy changes speed once per belt conveyor length interval, the speed change result only refers to the belt speed at the moment of the belt conveyor speed change. Since the transmitted frequency signal is a digital signal and the frequency modulation of the inverter is affected by the switching speed of the circuit thyristor, the frequency modulation and speed change are carried out at equal intervals. The PID algorithm also uses a discretization model to determine the motor output speed based on the motor speed and the reference speed, and converts it into frequency.

[0104] The fuzzy PID algorithm adjusts the motor speed and controls the motor speed according to the desired speed value and the given motor speed change curve. The motor speed will fluctuate greatly within the speed change time interval due to the constant change of the load, and it cannot be accelerated to the desired speed using an S-curve. Compared with the traditional PID algorithm, the two-degree-of-freedom PID algorithm adjusts the external disturbance suppression characteristics and the target following characteristics separately so that they can reach the optimal set value at the same time. P(S) is the process transfer function of the controlled object, X(S) is the set point controller transfer function, C(S) is the feedback controller transfer function, D(S) is the load disturbance, R(S) is the set point, and Y(S) is the control variable. There are two adjustable elements here, namely C(S) and X(S), which are described as , , b is the setpoint weight on the proportional term, and c is the setpoint weight on the derivative term. b and c have no effect on closed-loop stability because the location of the closed-loop poles depends only on C(S).

[0105] Specifically, the controller controls the inverter in the composite inverter unit through the following process:

[0106] S51: Using the Takagi–Sugeno–Kang rule as a fuzzy method for matching models, a belt speed-coal flow matching model is established according to formula (4), and the given speed value of the conveyor belt in the next cycle is obtained based on the belt speed-coal flow matching model;

[0107] (4);

[0108] Where, is the matching degree between the conveyor belt running speed data and the coal flow data, represents a type-one fuzzy set, where , is the number of inference rules, each of which has r antecedent factors; , represents r input data;

[0109] S52: Convert the conveyor belt speed curve into the motor speed desired curve according to formula (5), and obtain the motor desired speed value based on formula (5) ;

[0110] (5);

[0111] Where, Indicates the efficiency factor of the reducer or the loss caused by gear wear. Indicates the maximum speed of the conveyor belt. Indicates the maximum motor speed, and estimates the output motor given speed in a linear manner; Indicates the speed of a given conveyor belt;

[0112] S53: Obtain the acceleration of the motor's desired speed curve according to formula (6) ;

[0113] (6);

[0114] Where, Indicates the current speed of the motor; Indicates the acceleration and deceleration time of the belt conveyor; the change trend first gradually increases and then gradually decreases, so a fixed PID parameter set It may not be suitable for the entire speed change process and may cause speed overshoot. During the acceleration and deceleration process, different PID parameters need to be selected according to the different acceleration levels to adjust the output of the two-degree-of-freedom PID. The PID algorithm is self-tuned and modified in real time through the type 2 fuzzy algorithm.

[0115] S54: Combine the two-degree-of-freedom PID and type-II fuzzy control methods to intercept the motor's desired speed curve line segment at equal intervals, calculate the speed difference between the motor's desired speed and the current motor speed based on the desired speed, and calculate the approximate acceleration of the line segment at the same time, using the parameter , Amplify the speed difference and acceleration, and then use the amplified speed difference and acceleration as input data to output a proportional coefficient for adjusting the two-degree-of-freedom PID. and Parameters, no adjustment The main purpose is to improve the response speed of the PID algorithm. According to the parameters after speed adjustment, the speed compensation amount is output, and then the final target speed is obtained based on the sum of the current speed and the speed compensation amount.

[0116] S55: The two-degree-of-freedom PID algorithm combines the output of the type-II fuzzy control system with the filter coefficients, external disturbance suppression characteristics, and target following characteristics weights to calculate the desired speed interpolation and the sum of the current speed to control the motor speed. The speed information is converted into a digital frequency signal. After obtaining the motor speed, we also need to convert the speed into a digital signal that can be recognized by the inverter. According to formula (7), the final target speed is proportionally converted to the inverter frequency. ;

[0117] (7);

[0118] Where, is the final target speed of the motor, p is the number of pole pairs of the motor, is the power frequency;

[0119] S56: According to the principle of DA conversion inside the inverter to control the inverter, the video is converted into digital information and the speed setting value is obtained according to formula (8) , and output the speed setting value To the inverter;

[0120] (8);

[0121] Where, Indicates the reference speed of the motor, and n is the number of bits of the DA conversion control inverter.

[0122] The present invention provides an energy-saving and consumption-reducing control method for a multi-stage variable-frequency-driven underground belt conveyor. This method addresses the problems of severe energy waste, high starting current, and low intelligence level associated with conventional underground belt conveyors, as identified in the aforementioned background art. The present invention's technical solution enables the belt conveyor to adjust its operating speed in real time based on coal flow, reducing energy consumption. This method also minimizes the impact of starting current on the power grid and equipment, improving the intelligent control level of conveying equipment, and thereby significantly reducing coal mine production costs and improving production efficiency.

[0123] Compared with the prior art, the present invention has the following advantages:

[0124] 1. Significant energy savings: The coordinated operation of coal flow monitoring sensors and controllers allows precise adjustment of belt conveyor speed based on real-time changes in coal flow. This reduces speed when coal flow is low, avoiding energy waste caused by high-speed idling. Extensive field testing has demonstrated a 30%-40% reduction in energy consumption, significantly lowering coal mine production costs.

[0125] 2. Reduced starting current surge: During startup, the composite frequency conversion unit gradually increases frequency and voltage according to a preset startup curve, achieving a soft start for the belt conveyor. This significantly reduces starting current, lowering the impact on the power grid by approximately 70%-80%. It also reduces mechanical wear on the conveying equipment, extending its service life and lowering maintenance costs.

[0126] 3. Improved Intelligent Control: The controller provides intelligent control of the belt conveyor based on pre-set control strategies and algorithms. Furthermore, the human-machine interface facilitates operator parameter setting and operational status monitoring, improving the convenience and efficiency of production management. This makes the belt conveyor's operation more stable and reliable, enabling it to better adapt to the complex and ever-changing underground production environment.

[0127] This method has low implementation cost, high intelligence and ideal energy-saving effect. It can adjust the working mode of multiple frequency converters in real time according to the coal flow rate, and can intelligently adjust the running speed of the conveyor belt based on the matching technology of belt speed and coal flow rate. At the same time, it has good starting characteristics, which is conducive to extending the service life of the conveying equipment.

[0128] The present invention also provides an energy-saving and consumption-reducing control system for an underground belt conveyor driven by a multi-stage frequency conversion drive, comprising a coal flow monitoring sensor, a speed sensor, a composite frequency conversion unit, a human-machine interaction interface and a controller;

[0129] The coal flow monitoring sensor is a high-precision electronic belt scale, which is installed on the belt conveyor and is used to collect the coal flow weight signal on the conveyor belt in real time;

[0130] The speed sensor is installed on the driving roller of the belt conveyor and is used to collect the running speed signal of the driving roller in real time;

[0131] The composite frequency conversion unit includes a main frequency conversion unit, an auxiliary frequency conversion unit 1 and an auxiliary frequency conversion unit 2. The main frequency conversion unit includes a main frequency converter (160kW) and a main motor connected to each other; the auxiliary frequency conversion unit 1 includes an auxiliary frequency converter 1 (110kW) and an auxiliary motor 1 connected to each other; the auxiliary frequency conversion unit 2 includes an auxiliary frequency converter 2 (90kW) and an auxiliary motor 2 connected to each other; the main motor, the auxiliary motor 1 and the auxiliary motor 2 are all connected to the drive shaft of the drive roller through a reducer; preferably, the main frequency converter can serve as the core control unit and cooperate with the auxiliary frequency converter to realize dynamic power distribution; further preferably, the PROFINET bus can be used to ensure multi-machine synchronous control (frequency deviation <0.5Hz), thereby realizing multi-level precise control of the belt conveyor running speed;

[0132] The controller is connected to the coal flow monitoring sensor, the speed sensor and the composite frequency conversion unit respectively, and is used to obtain coal flow data and conveyor belt running speed data based on the coal flow weight signal and the running speed signal, and send corresponding control signals to the composite frequency conversion unit based on the coal flow data and the conveyor belt running speed data, thereby realizing intelligent control of the belt conveyor;

[0133] The human-machine interaction interface is connected to the controller and is used to provide a human-machine interaction interface. At the same time, it is used to display coal flow data, operating speed data, and the operating status of the composite frequency conversion unit.

[0134] In order to facilitate timely execution of warning actions when an abnormality occurs to effectively remind relevant personnel, an audible and visual alarm module is also included. The audible and visual alarm module is installed on the belt conveyor and connected to the controller.

[0135] Preferably, the speed sensor utilizes a rotary encoder, preferably one with fast response speed and high precision, which outputs a pulse signal after acquiring the signal. The human-machine interface utilizes a touchscreen display, allowing operators to intuitively and conveniently set various parameters on the interface, such as the coal flow threshold and speed adjustment range. Furthermore, the operator can conveniently view the operating status of the belt conveyor in real time, including parameters such as coal flow, operating speed, motor current, voltage, and alarm information, facilitating timely detection and resolution of problems.

[0136] In order to facilitate signal amplification and filtering, a signal processing module is also included. The controller is connected to the coal flow monitoring sensor and the speed sensor through the signal processing module.

[0137] In order to facilitate real-time perception of the speed data of each motor, the main motor is equipped with a motor speed sensor 1, the auxiliary motor 1 is equipped with a motor speed sensor 2, and the auxiliary motor 2 is equipped with a motor speed sensor 3.

[0138] As a preferred embodiment, the controller is a high-performance programmable logic controller (PLC) controller. The two signal input terminals of the PLC controller are respectively connected to the signal output terminals of the coal flow monitoring sensor and the speed sensor, so as to receive the coal flow quality signal and the operating speed signal in real time. Its three signal output terminals are connected to the control signal input terminals of the three frequency converters in the composite frequency conversion unit, so as to perform accurate calculation and analysis based on the preset control strategy and the received monitoring data, and send accurate control signals to the frequency converter in the composite frequency conversion unit based on the processing results, thereby realizing intelligent control of the belt conveyor.

[0139] In the present invention, the provision of a coal flow monitoring sensor facilitates real-time acquisition of coal flow weight signals during belt conveyor conveying operations, thereby enabling the controller to sense coal flow data on the conveyor belt in real time. Connecting a speed sensor to the drive roller facilitates real-time acquisition of the drive roller's operating speed signal during belt conveyor conveying operations, thereby enabling the controller to calculate the conveyor belt's operating speed data based on the drive roller's operating speed data. The composite frequency conversion unit comprises a main frequency conversion unit, a first auxiliary frequency conversion unit, and a second auxiliary frequency conversion unit. This innovatively employs a coordinated operation architecture of a main frequency converter and two slave frequency converters in the belt conveyor. Consequently, when the load is low, only the main frequency converter operates; when the load is medium, the main frequency converter and the first auxiliary frequency converter operate in conjunction; and when the load is high, the main frequency converter and the two auxiliary frequency converters operate together. This allows different combinations of drive force to be provided according to different loads, effectively saving energy consumption and achieving multi-level precise control of the belt conveyor's operating speed. Through the setting of the human-computer interaction interface, not only can relevant personnel observe the operating status of the belt conveyor in real time, but also relevant personnel can adjust and optimize parameters such as the coal flow threshold and speed adjustment range through the human-computer interaction interface according to actual production conditions and long-term experience accumulation, so that the control system can better adapt to different working conditions and production needs.

[0140] The system has a simple structure, low manufacturing cost and ideal energy-saving effect. It can intelligently select the working combination mode of multiple inverters in the composite frequency conversion unit according to the load conditions, which can effectively save energy consumption. At the same time, it can achieve multi-level precise control of the belt conveyor's operating speed.

Claims

1. A multi-stage variable frequency drive underground belt conveyor energy saving and consumption reduction control method, characterized in that: The following steps are included: Step 1: Install the coal flow monitoring sensor on the belt conveyor and the speed sensor on the driving roller of the belt conveyor; Step 2: During the operation of the belt conveyor, the coal flow monitoring sensor is used to collect the coal flow weight signal on the conveyor belt in real time and send it to the signal processing module. The speed sensor is used to collect the running speed signal of the driving roller in real time and send it to the signal processing module; The signal processing module amplifies and removes noise from the coal flow weight signal and the running speed signal and then sends them to the controller; Step 3: The controller obtains the coal flow data and the conveyor belt running speed data according to the coal flow weight signal and the running speed signal, and performs filtering processing to obtain high-precision monitoring data; Step 4: Abstract and construct type-2 fuzzy sets of input parameters; The speed of the conveyor belt The domain is set as follows: 0< <0.9 corresponds to the ultra-low speed state T, and 0.9≤ <1.7 corresponds to the medium and low speed state TM, and 1.7≤ <2.5 corresponds to the medium speed state M, and 2.5≤ <3.3 corresponds to the medium and high speed state Q, and 3.3≤ ≤4.5 corresponds to the maximum speed state QA; The coal flow The domain is set as follows: 0≤ <20 corresponds to low flow state LL, 20≤ <40 corresponds to the low to medium flow state L, and 40≤ <60 corresponds to the medium flow state M, and 60≤ <80 corresponds to the medium and high flow state HM, and 80≤ ≤100 corresponds to full load flow state H; Set the output matching degree as follows: -2 corresponds to a 2-speed reduction, -1 corresponds to a 1-speed reduction, 0 corresponds to maintaining the current speed, 1 corresponds to a 1-speed increase, and 2 corresponds to a 2-speed increase. Step 5: Start the belt conveyor and perform multi-level precise control on the belt conveyor by combining two-degree-of-freedom PID and type-two fuzzy sets; When the belt conveyor starts, the controller sends a specific start-up control signal to the composite frequency conversion unit, so that the composite frequency conversion unit gradually and slowly increases the frequency and voltage according to the preset start-up curve; When 0≤<20, the controller controls the composite frequency conversion unit to stop completely and enter the shutdown mode; When 20≤ When the value is less than 40, the controller controls the main frequency conversion unit to operate; When 40≤ When the value is less than 60, the controller controls the main frequency conversion unit and the auxiliary frequency conversion unit to run simultaneously; When 60≤ When the value is less than 80, the controller controls the main frequency conversion unit, auxiliary frequency conversion unit 1 and auxiliary frequency conversion unit 2 to run simultaneously; When 80≤ When ≤100, the controller controls the main frequency conversion unit, auxiliary frequency conversion unit 1 and auxiliary frequency conversion unit 2 to run simultaneously.

2. The energy-saving and consumption-reducing control method for a multi-stage frequency conversion driven underground belt conveyor according to claim 1 is characterized in that: In step three, the specific process of obtaining high-precision monitoring data is as follows: S31: Combining the kinematic characteristics of the belt conveyor with the layout of the coal flow monitoring sensor and speed sensor, the state vector is defined according to formula (1): ; （1）； Where, For conveyor belt The running speed data at the moment, For conveyor belt The load at the moment, is the transpose operation; S32: Establish a state equation based on the belt conveyor motion model according to formula (2); establish an observation equation based on the belt conveyor motion model according to formula (3); （2）； Where, for The state of the moment; for The state of the moment; is the state transition matrix, , is the sampling time interval, is the friction coefficient of the conveyor belt, for Motor current at the moment; is the control input matrix, , is the equivalent mass of the conveyor belt; is the motor torque control quantity; is the process noise; （3）； Where, for The measured value of the sensor at each moment; is the observation matrix, , Calibrate the system for load cells; is the observation noise; S33: Continuously modify the state scheme through the observation equation and use the Kalman gain Recursively update the state estimate and covariance matrix to output high-precision monitoring data.

3. The energy-saving and consumption-reducing control method for a multi-stage variable frequency driven underground belt conveyor according to claim 2, characterized in that: In step 5, the controller controls the inverter in the composite inverter unit through the following process: S51: establishing a belt speed and coal flow matching model according to formula (4), and obtaining a given speed value of the conveyor belt for the next cycle based on the belt speed and coal flow matching model; （4）； Where, is the matching degree between the conveyor belt running speed data and the coal flow data, represents a type-one fuzzy set, where , is the number of inference rules; , represents r input data; S52: Convert the conveyor belt speed curve into the motor speed desired curve according to formula (5), and obtain the motor desired speed value based on formula (5) ; （5）； Where, Indicates the efficiency factor of the reducer or the loss caused by gear wear. Indicates the maximum speed of the conveyor belt. Indicates the maximum motor speed; Indicates the speed of a given conveyor belt; S53: Obtain the acceleration of the motor's desired speed curve according to formula (6) ; （6）； Where, Indicates the current speed of the motor; Indicates the acceleration and deceleration time of the belt conveyor; S54: Combine the two-degree-of-freedom PID and type-II fuzzy control methods to intercept the motor's desired speed curve line segment at equal intervals, calculate the speed difference between the motor's desired speed and the current motor speed based on the desired speed, and calculate the approximate acceleration of the line segment at the same time, using the parameter , Amplify the speed difference and acceleration, and then use the amplified speed difference and acceleration as input data to output a proportional coefficient for adjusting the two-degree-of-freedom PID. and Parameters, according to the speed-adjusted parameters, output the speed compensation amount, and then get the final target speed based on the sum of the current speed and the speed compensation amount; S55: Convert the final target speed into the inverter frequency in proportion according to formula (7) ; （7）； Where, is the final target speed of the motor, p is the number of pole pairs of the motor, is the power frequency; S56: According to the principle of DA conversion inside the inverter to control the inverter, the video is converted into digital information and the speed setting value is obtained according to formula (8) , and output the speed setting value To the inverter; （8）； Where, Indicates the reference speed of the motor, and n is the number of bits of the DA conversion control inverter.

4. A multi-stage variable frequency drive underground belt conveyor energy-saving and consumption-reducing control system, used to implement the multi-stage variable frequency drive underground belt conveyor energy-saving and consumption-reducing control method according to any one of claims 1 to 3, characterized in that: It includes coal flow monitoring sensor, speed sensor, composite frequency conversion unit, human-machine interface and controller; The coal flow monitoring sensor is a high-precision electronic belt scale, which is installed on the belt conveyor and is used to collect the coal flow weight signal on the conveyor belt in real time; The speed sensor is installed on the driving roller of the belt conveyor and is used to collect the running speed signal of the driving roller in real time; The composite frequency conversion unit includes a main frequency conversion unit, an auxiliary frequency conversion unit 1 and an auxiliary frequency conversion unit 2. The main frequency conversion unit includes a main frequency converter and a main motor connected to each other; the auxiliary frequency conversion unit 1 includes an auxiliary frequency converter 1 and an auxiliary motor 1 connected to each other; the auxiliary frequency conversion unit 2 includes an auxiliary frequency converter 2 and an auxiliary motor 2 connected to each other; the main motor, the auxiliary motor 1 and the auxiliary motor 2 are all connected to the transmission shaft of the drive drum through a reducer; The controller is connected to the coal flow monitoring sensor, the speed sensor and the composite frequency conversion unit respectively, and is used to obtain coal flow data and conveyor belt running speed data based on the coal flow weight signal and the running speed signal, and send corresponding control signals to the composite frequency conversion unit based on the coal flow data and the conveyor belt running speed data, thereby realizing intelligent control of the belt conveyor; The human-machine interaction interface is connected to the controller and is used to provide a human-machine interaction interface. At the same time, it is used to display coal flow data, operating speed data, and the operating status of the composite frequency conversion unit.

5. The energy-saving and consumption-reducing control system for a multi-stage variable frequency driven underground belt conveyor according to claim 4 is characterized in that: It also includes an audible and visual alarm module, which is installed on the belt conveyor and connected to the controller.

6. The energy-saving and consumption-reducing control system for a multi-stage variable frequency driven underground belt conveyor according to claim 5, characterized in that: The speed sensor adopts a rotary encoder, and the human-machine interaction interface adopts a touch screen.

7. The energy-saving and consumption-reducing control system for a multi-stage variable frequency driven underground belt conveyor according to claim 6, characterized in that: It also includes a signal processing module, and the controller is connected to the coal flow monitoring sensor and the speed sensor through the signal processing module.

8. The energy-saving and consumption-reducing control system for a multi-stage variable frequency driven underground belt conveyor according to claim 7, characterized in that: The main motor has a built-in motor speed sensor 1, the auxiliary motor 1 has a built-in motor speed sensor 2, and the auxiliary motor 2 has a built-in motor speed sensor 3.

9. The energy-saving and consumption-reducing control system for a multi-stage variable frequency driven underground belt conveyor according to claim 8, characterized in that: The controller is a PLC controller.

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