McEnino Electric Co., Ltd. uses two KE300-132G/160P-T4 frequency converters to transform the belt conveyors of the Yangcheng Coal Mine in Shanxi Province. After the transformation, the system started smoothly with heavy load, balanced power distribution, and a small amount of system maintenance, and achieved good economic benefits.
I. Introduction
Belt conveyor is an important transportation tool in coal mine production. The normal operation of the system directly affects the safety production of the mine. Therefore, the stable operation of the belt conveyor system is particularly important.
Traditional conveyors generally use hydraulic coupler speed control methods, using less frequency conversion technology. Due to the disadvantages of low precision of fluid coupling, low energy saving effect, inconvenient installation and large daily maintenance cost, the frequency conversion technology has a broad application prospect in coal mine conveyors.
Second, technical difficulties analysis
Coal mine underground belt conveyors are divided into dual-drum drive and multi-drum drive. Each drive roller is driven by a single motor, and each motor is driven by a single inverter. Synchronization of the system has become a difficult point in frequency conversion. The poor synchronization results in uneven power distribution. As a result, the output current of one of the inverters or the overvoltage is too large and the alarm occurs, thus affecting the normal operation of the entire system.
Use the droop control function of the KE300 series inverter to realize the dynamic balance of output power of multiple inverters and motors and solve the overcurrent problem caused by uneven power distribution.
A common DC bus scheme is adopted for multiple inverters to solve the overvoltage problem caused by poor synchronization.
Third, the specific transformation program
Dual-drum drive for belt conveyors in the Yanglong coal mine in Yangcheng, Shanxi (Figure 1)
Figure 1 double drum drive
The drag motor is an asynchronous motor, and the motor parameters are: a 4-level asynchronous motor 110KW, a rated frequency of 50Hz, a rated voltage of 380V, a rated current of 199A, and a rated speed of 1485r/min. The ratio of the motor to the speed reducer is 31:5. More than 500 meters long belt.
According to the actual needs of the scene, the control schematic is as follows:
Figure 2 control schematic
According to the actual needs of the site, the parameters are set as follows:
One inverter
Second inverter
Functional description
P0-02 = 1
P0-02 = 1
Terminal command channel
P0-03 = 2
P0-03 = 2
Analog AI1 setting frequency
P0-10 = 50.10
Maximum output frequency
P0-12 = 50.08
Maximum frequency
P0-17 = 150S
P0-17=150S
acceleration time
P4-00 = 1
P4-00 = 1
Forward operation
P4-01 = 9
P4-01 = 9
Fault reset
P5-02 = 2
P5-02 = 2
Relay fault output
P6-01 = 1
P6-01 = 1
S curve acceleration and deceleration
Figure 3 live use picture
Fourth, the conclusion
1. Using the built-in droop control function, it realizes the dynamic balance of the output power of multiple inverters and motors, and solves the problem of inverter over-current alarm caused by unbalanced output power.
2. The scheme of common DC bus is adopted to solve the problem of overvoltage alarm caused by the poor synchronization of the motor.
3. The S-curve acceleration/deceleration method and torque boosting function are adopted to solve the problems of heavy-load smooth start-up.
4. The two inverters' fault output signal and the operation enable signal are connected in series to realize the automatic shutdown protection of any inverter when the inverter is faulty.