Application of Sunwoele VFD (Variable-frequency Drive) on Belt Conveyor of Xinjiang Coking Coal Group

I. Overview

With the continuous maturity and improvement of frequency conversion speed regulation technology at home and abroad in modern China, VFD (Variable-frequency Drive) has the characteristics of wide speed regulation range, high precision, smooth speed regulation, stability and reliability, hard motor speed regulation characteristics, and remarkable energy saving effect. , Gradually replace the traditional DC speed control and hydraulic coupling, hydraulic resistance and electromagnetic speed control equipment. Widely used in metallurgy, petroleum, chemical industry, cement, mining and other fields. Chengdu Sunwoele HFV3000 high-voltage VFD (Variable-frequency Drive) is in a leading position in China's domestic high-voltage frequency conversion industry because of its unique and distinctive features such as advanced control technology, powerful control functions, safety and reliability. Xinjiang Coking Coal Group selected HFV3000 VFD (Variable-frequency Drive) through bidding to apply it to the control of belt conveyors in inclined shafts of coal mines. After nearly two years of operation, the operation is safe, stable and reliable, and has produced good economic benefits.

2. Working environment and working conditions

The mining area of Xinjiang Coking Coal Group is located in a mountainous area. The altitude of the mining area is 2000-2200m. The highest ambient temperature in summer is 41°C, and the lowest temperature in winter is -30°C. There are three wellheads with an annual output of 1.2 million tons in the mining area. The gas coal inclined shaft of Xinjiang Coking Coal Group uses an inclined shaft belt conveyor to transport coal from underground to the ground. The daily coal production is about 3500t, the belt length is 650m, the belt inclination angle is 19°～24°, the belt drive motor is 400kW, and the power supply is 6kV dual power supply. These working conditions require that the motor starting control equipment can operate stably and reliably in high altitude areas, and at the same time have a strong overload capacity and be able to adapt to a wide range of voltage fluctuations.

The belt motor was originally designed to be started directly. Later, it was considered that the direct start of the motor would have a large impact on the power grid and transmission machinery equipment, and it was always running at full speed during operation, which was not conducive to saving energy consumption. After careful investigation and comparison of various high-voltage VFDs (Variable-frequency Drive) at home and abroad in China, the HFV3000 high-voltage VFD (Variable-frequency Drive) of Chengdu Sunwoele Co., Ltd., which has advantages in terms of cost performance, product quality and service, was finally selected by bidding. ) as the control equipment of the belt conveyor.

3. Usage

Considering factors such as high altitude and high ambient temperature in summer, appropriate margins are left when selecting the VFD (Variable-frequency Drive). The motor power is 400kW, the rated voltage is 6kV, and the rated current is 38.49A. Xinjiang Coking Coal Group selected Sunwoele's VFD (Variable-frequency Drive) HFV3000-Y06/061 with a rated voltage of 6kV and a rated current of 61A to control a 400kW belt motor. The VFD (Variable-frequency Drive) is equipped with an automatic bypass cabinet, so that it can automatically bypass to the grid power frequency operation in case of failure to ensure continuous and uninterrupted production. After the bypass operation, it is convenient to cut off the VFD (Variable-frequency Drive) input, The output side isolating switch and vacuum circuit breaker make the VFD (Variable-frequency Drive) separate from the high-voltage power supply, which can be easily maintained. VFD (Variable-frequency Drive) has been debugged and put into use in April 2006. So far, there has been no downtime due to failure, and the operation is in good condition.

The VFD (Variable-frequency Drive) cooling fan is in good heat dissipation. However, due to the large amount of coal ash and dust on site, it is necessary to regularly remove the dust on the cooling device, and the measures to reduce environmental dust are being solved now. Due to the use of multiple pulse width modulation technology and series overlapping wave output, the output waveform is not distorted, close to the perfect sine wave waveform, no harmonic pollution, and no filtering device is required. It meets the control requirements of the power sector for the harmonic content of the power grid. There is no interference to the surrounding electrical equipment and the comprehensive protection device of the nearby belt conveyor. It reduces the noise and heat of the motor, does not cause torque ripple of the motor, and has no special requirements for the motor. The operating power factor can reach more than 0.95, and the efficiency can reach more than 96%.

Based on the powerful control function of HFV3000 high-pressure VFD (Variable-frequency Drive), simple and intuitive operation mode, stable and reliable operation, and its successful application in gas coal wells of Xinjiang Coking Coal Group, it is favored by Xinjiang Coking Coal Group. When the 2130 mine was expanded in July 2006, Coking Coal Group selected another set of HFV3000-Y06/077 (800kVA) high-voltage VFD (Variable-frequency Drive) for the control of the 2130 mine belt conveyor. Gas Coal Well plans to expand production, plans to increase belt transportation capacity, and changes the original belt conveyor to dual-machine drive. In September 2007, Gas Coal Well added another set of HFV3000 -Y 06/061VFD (Variable-frequency Drive ).

4. Working principle

HFV3000VFD (Variable-frequency Drive) adopts AC-DC-AC voltage source type. Apply mature low-voltage frequency conversion technology, advanced unit series stacking wave structure, and sine wave PWM modulation method of space vector control. Each phase consists of 5 power units connected in series. The high-voltage 6kV power supply is directly input to the high-voltage side of the isolation transformer, and the secondary side of the transformer outputs three-phase 690V voltage after step-down and phase-shifting to supply power to each power unit respectively. The power unit goes through three links of three-phase full-bridge rectification-DC filtering-single-phase inverter output, and then each unit of each phase is connected in series, and the three-phase star connection directly outputs high voltage 6kV to drive the motor to run. The input side is equivalent to 30-pulse rectification, and the output side is equivalent to 11-level stacked waves per phase.