1.Overview

Coal mining follow the requirements of wind, coal mining and wind volume has a certain corresponding relationship, air volume increases with the increase of coal production, and ensure the fresh air of coal miners and coal mining, so for coal mine production safety, fan supply air volume and wind pressure should extend with the mining and excavation, roadway extension, and the increase of mining and timely adjustment.

2.Implementation plans

The traditional method is to adjust the valve, but the worst efficiency is to artificially change the resistance curve and adjust the air resistance by increasing the wind resistance; The guide regulator and the tail angle are higher than the valve; changing the characteristic curve of the fan can change the fan to operate with a high efficiency and can achieve the purpose of energy saving and consumption reduction to a certain extent. In order to avoid the panting phenomenon of the fan, and make the fan have the highest operating efficiency and energy saving effect under a variety of air volume conditions, under the current technical conditions, the frequency conversion speed regulation scheme is the best choice. Because the air volume required by the coal mine in the initial stage of the fan operation is obviously smaller, or even much smaller, compared with the maximum air volume available for the fan, the energy saving effect is especially obvious in the initial stage of the fan operation.

2 BD- -10-NO: 32 rotary axial ventilation main fans, a total of 4400kW 6kV motors, 4 FD5000 medium voltage drive. The main technical parameters of frequency converter are as follows: the power of frequency converter is 560kW; the operating frequency is 50Hz; the input voltage is 6.0kV ± 20%; the output voltage is three-phase sine wave voltage is 0~6kV and the output frequency is 0~60Hz. The high voltage frequency conversion speed regulation system adopts the direct "high-high" transformation form, which is a unit series multi-level topology structure, and the main structure has multiple groups of power modules in parallel. The frequency conversion device controls the HMI control mode, which can increase, reduce load and stop from the local interface. The device keeps a fault record for at least one year. The frequency converter provides two communication functions: the standard RS-485 and a communication interface with a touch screen processor extension. In the range of 20%~100%, the power factor of the local input terminal can reach 0.95 without any power factor compensation. The frequency conversion device has no requirements on the length of the output cable, and the frequency conversion device protects the motor from the common mode voltage and dvdt stress. The output current harmonic of the frequency conversion device is not more than 2%, which meets the requirements of IEEE 5191992 and the Chinese power sector, and is higher than the harmonic distortion requirements of the national standard GB 14549- -1993. The output waveform of the frequency conversion device will not cause the resonance of the motor, and the torque pulsation is less than 0.1%. The frequency converter can automatically skip the resonance point. The frequency conversion device has a strong adaptability to the voltage fluctuation of the power grid, and can still output at full load when the grid voltage fluctuation of-10%~ + 10%. The frequency conversion device has a perfect protection function and a fault self-diagnosis function.

3.Application advantages

(1)FD5000 medium voltage drive SVC control and open loop torque control perfectly solve the problem of large starting torque of ball mill;

(2)FD5000 medium voltage drive can improve efficiency, no pollution, high power factor;

(3) Advanced fault unit bypass operation;

(4) High-performance control technology;

(5) High reliability;

(6) Strong fault self-diagnosis ability.