[ summary of the invention ]
The invention aims to solve the technical problem of providing an intelligent high-voltage frequency conversion main coal flow conveying system with sensitive conveying speed adjustment and low failure rate.
In order to solve the technical problems, the invention adopts the technical scheme that the control method of the high-voltage frequency conversion main coal flow intelligent conveying system comprises a torque detection system, a control system and a high-voltage frequency conversion transmission system, wherein the high-voltage frequency conversion transmission system comprises a conveying belt driven by a plurality of frequency conversion motors; the torque detection system sends a torque sampling signal of the variable frequency motor to the control system, the control system converts the torque sampling signal into torque data, estimates the coal amount of the current conveyor belt load according to the torque data, controls the high-voltage variable frequency transmission system according to the torque data and/or the estimated coal amount, and adjusts the running speed of the conveyor belt.
In the operation control method, the operation speed zone of the conveying belt is divided into N speed zones in advance, wherein N is a positive integer greater than 1; each speed interval is respectively corresponding to the judgment time of the coal quantity value and the conversion speed of the conveying belt; when the conveying belt runs in a certain speed interval, when the estimated coal amount calculated by the control system is continuously smaller than the coal amount value of the speed interval within the judging time of the speed interval, the control system outputs a signal to control the conveying belt to decelerate to a lower-level speed interval to run, and if the speed interval is the lowest speed interval, the conveying belt keeps running in the lowest speed interval; when the estimated coal amount calculated by the control system is continuously larger than the coal amount value of the speed interval within the judgment time of the speed interval, the control system outputs a signal to control the conveying belt to accelerate to a higher speed interval for running, and if the speed interval is the highest speed interval, the conveying belt keeps running in the highest speed interval.
In the above operation control method, the estimated coal amount is calculated according to the following formula:
Y=kX+C
y: estimating the coal amount: the current coal quantity borne by the whole conveying belt;
k: estimating coefficients: the set value is determined by the density of the coal and the length and width of the conveying belt;
x: torque: the sum of the torques of all driving motors of the conveying belt;
c: compensation amount: and setting after comparing the actual coal output with the estimated coal amount.
The operation control method dynamically adjusts the judging time of the switching speed of the conveying belt, the judging time is shorter when the coal amount changes from small to large, and the judging time is correspondingly longer when the coal amount changes from large to small.
In the operation control method, one of the plurality of variable frequency motors is set as a master machine, and the rest are slave machines; when the torque of the slave is lower than that of the master, the control system controls the slave to increase the torque; when the torque of the slave is higher than that of the master, the control system controls the slave to reduce the torque.
In the operation control method described above, the adjusted slave torque is the current slave output torque x (1+ △), and Δ is k1 × Δ 1+ Δ y;
Δ: dynamic difference in%;
k 1: adjusting the coefficient;
Δ 1: the ratio of the dynamic torque difference between the master and the slave to the difference of the rated load torque minus the no-load torque;
Δ y: the difference value compensation ratio of the coal transportation quantity is expressed in percentage.
The coal flow conveying speed adjusting device has the advantages of sensitive adjustment, low failure rate, good energy-saving effect of the system and reduced operation cost of equipment.
[ detailed description of the invention ]
As shown in fig. 1, the mining high-voltage frequency-conversion main coal flow conveying system according to the embodiment of the present invention is driven by a 10kV (6kV) high-voltage frequency converter, and includes a torque detection system, an intelligent control system, and a high-voltage frequency-conversion transmission system.
The torque detection system, the intelligent control system and the high-voltage variable-frequency transmission system are all installed in the mining explosion-proof and intrinsically safe box body, and the main working principle is as follows:
the output torque signal of the motor output by the torque detection system is sampled and then sent to the intelligent control system, the intelligent control system generates the signal into calculable torque data, the size of the coal quantity loaded by the current conveying belt is estimated and generated according to the group of data, the calculated and estimated coal quantity is compared with the corresponding coal quantity set by the current system, and finally the output of the current system is controlled according to the torque and/or the estimated coal quantity, so that the high-voltage variable-frequency transmission system is controlled, and the purposes of stabilizing the operation of the system and saving energy of the system are achieved.
In order to complete the control function, a multi-motor torque balance control method and a coal quantity estimation automatic energy-saving operation control method are adopted, the multi-motor torque balance control method mainly controls the output of a motor in the operation process, the coal quantity estimation automatic energy-saving operation control method mainly controls the overall operation speed of the system, the control of the multi-motor torque balance control method and the control of the coal quantity estimation automatic energy-saving operation control method are complementary, the real-time control of the whole system is jointly completed, and the long-term and reliable operation of the system is guaranteed.
Coal quantity estimation and automatic energy-saving operation control method
The estimated coal amount is calculated in real time in the intelligent control system, and the estimation formula is as follows:
Y=kX+C
y: estimating the coal quantity (namely the coal quantity currently carried by the whole conveyor belt);
k: estimation coefficients (set values, determined by the density of the coal, the length and width of the conveyor belt);
x: torque (sum of all motor torques in the system);
c: and (4) compensating quantity (set after the actual coal output quantity is compared with the estimated coal quantity on site).
The adjustment control method for estimating the coal amount in real time is as follows (taking setting three-stage speed as an example):
the system sets three-stage speeds for the conveyer belt in advance, wherein the three speeds are respectively low speed, medium speed and high speed, and three coal quantity values and determination time of conversion speed under the three-stage speeds are set corresponding to the three speeds respectively.
When the system runs at a low speed, the estimated coal amount calculated by the intelligent control system is continuously less than or equal to the low-speed coal amount value set in the low-speed interval within the corresponding judgment time, the intelligent control system outputs a signal to control the running rotating speed of the system to be kept at the low speed for running, and when the estimated coal amount calculated by the intelligent control system is continuously greater than the low-speed coal amount value set in the low-speed interval within the corresponding judgment time, the intelligent control system outputs a signal to control the system to be accelerated to run at a medium speed.
When the system runs at a medium speed, the estimated coal amount calculated by the intelligent control system is continuously smaller than the set medium-speed coal amount value in the medium-speed interval within the corresponding judgment time, the intelligent control system outputs a signal to control the running rotating speed of the system to be decelerated to a low-speed running, and when the estimated coal amount calculated by the intelligent control system is continuously larger than the set medium-speed coal amount value in the medium-speed interval within the corresponding judgment time, the intelligent control system outputs a signal to control the system to be accelerated to the high-speed running.
When the system is in high-speed operation, the estimated coal amount calculated by the intelligent control system is continuously smaller than the set high-speed coal amount value in the high-speed interval within the corresponding judgment time, the intelligent control system outputs a signal to control the operation rotating speed of the system to be decelerated to medium-speed operation, and when the estimated coal amount calculated by the intelligent control system is continuously equal to or larger than the set high-speed coal amount in the high-speed interval within the corresponding judgment time of speed change, the intelligent control system outputs a signal to control the system to be kept in high-speed operation.
When the coal quantity is increased, the system is required to respond as fast as possible, when the coal quantity is decreased, the system is instantaneously decreased and continuously decreased, if the quantity is not increased any more, the system is required to respond faster, and if the quantity is not increased any more continuously, the system is required to respond slower.
Therefore, after the determination time for switching the speed is set at three speeds in the system, in each operation, in order to ensure that the system has a faster speed response, the determination time for the speed change of the rotating speed from the lower speed to the higher speed is shorter, and the determination time for the speed change from the higher speed to the lower speed is longer, the determination time for the speed change in the speed reduction is automatically adjusted by the system according to the real-time estimated coal amount, the faster the coal amount is changed from small to large, the shorter the determination time for the speed change is, and the slower the coal amount is changed from large to small, the longer the determination time for the speed change is.
This dynamic adjustment of the decision time for the speed change results in a better energy saving without further influence on the coal transport quantity.
The problem that the energy-saving effect of the system is not obvious is solved by estimating the coal load of the system to adjust the running speed of the system, all the coal load on a conveying belt of the whole system is estimated, so that the problem that the adjustment is not timely or long-time and no adjustment is caused by different coal quantities at all sections of the conveying belt in coal flow detection is solved, the whole process is automatic adjustment, manual interference is not needed after parameters are set, and the system runs in a fully automatic energy-saving mode.
Two-motor and multi-motor torque balance control method
The multi-motor torque balance control method (taking the system as an example that N motors are operated, the system is divided into 1 host and N-1 slave machines, and the setting of the host and the slave machines does not influence the control process):
the dynamic difference Δ is estimated as follows:
Δ=k1*Δ1+Δy
Δ: dynamic difference
k 1: adjusting coefficient (the adjusting coefficient directly reflects the magnitude of dynamic difference speed regulation amplitude, the parameter is set during field debugging, if the value is set too small, the system dynamic adjustment is too slow, if the value is set too large, the system is easy to generate oscillation, the adjustment is too violent)
Δ 1: load unbalance between master and slave (ratio of dynamic torque difference between master and slave to rated load torque minus no-load torque)
Δ y: the coal conveying quantity difference compensation ratio (the value is a fixed value and is set during field debugging, the value is only set in a slave machine, can be positive compensation or negative compensation, the value of a master machine is default to 0, and the adjustment of the value mainly compensates the error of the speed of a conveying belt caused by the mechanical error between the master machine and the slave machine at the same rotating speed, so that the corresponding coal conveying quantity also has a difference.)
Compensated slave torque x (1+ △) current slave output torque
In the running process of the system, the intelligent control system automatically gives out a dynamic delta difference value according to the torque balance condition between the load and the multiple motors and participates in the torque balance control of the multiple motors, and the control process is shown in figure 2. When the torque of the slave machine is lower than that of the main machine, the intelligent control system controls the slave machine to increase the output torque properly by the output signal, and when the torque of the slave machine is higher than that of the main machine, the intelligent control system controls the slave machine to decrease the output torque properly by the output signal.
The adjustment amplitude, the adjustment coefficient, the acceleration and deceleration time of the system, the speed of each section of automatic energy-saving operation, the coal quantity value corresponding to each section of speed and the judgment time of corresponding speed change in the whole system can be set with different parameters according to different fields.
The multi-motor torque balance control method effectively solves the problem of unbalanced output of the master motor and the slave motor, and can effectively solve the problem of multi-motor torque balance precision under the condition of stable speed by adopting a dynamic difference delta compensation algorithm when load disturbance occurs and if the torque imbalance among the multiple motors occurs in a multi-motor torque balance operation system.
According to the embodiment of the invention, torque detection participation control is added in system control, and the sampled torque signal is calculated in the intelligent data calculation module and then is controlled in real time, so that the output of the motor is guaranteed as a control target in the acceleration process, the deceleration process or the speed stabilization process, the problem that the energy saving effect of equipment is not remarkable in use is solved, meanwhile, the system is adjusted more quickly and more stably in operation, the impact on the equipment caused by adjustment can be basically ignored, the energy saving effect of the whole system is obvious, the impact on the equipment in operation is greatly reduced, the problems of serious electric energy waste and serious equipment loss of most of underground coal mine equipment are fully solved, and the operation cost of users of the equipment is reduced. Thereby ensuring that the whole system can operate stably and efficiently for a long time.