converter blowing process, the mouth will emit large amounts of brown-red smoke, high temperature flue gas containing combustible gas and metal particles, according to "air pollutant emission standards" of 1996 was enacted (gb16297 a 1996), flue gas must be cooled and cleaned by the induced draft fan to exhaust chimney to diffuse or conveyed to gas recovery system in the back. thus, each converter to be equipped with a set of dust removal system, motor power 1400kw / 6kv. consider energy requirements, so in september 2009, the steel mill dust blower to transform the high voltage inverter speed control switch for the dust blower.
1.1 high-voltage inverter technical requirements and rehabilitation programs
dust blower power is central dust purification system, once the dust blower does not operate, not only affect production, causing huge economic losses, as well as potential threats to the safety of field production personnel; in addition, the speed control system working environment is bad; at the same time it periodically interrupted oxygen blowing converter; therefore, dust and high-pressure fan support speed control system is required to have high reliability. based on the above work characteristics, the main requirements for frequency control system is as follows:
1) requires the drive to have high reliability, long-term trouble-free operation.
2) requests the frequency bypass function in case of failure, the motor can switch to the frequency operation.
3) to a large speed range, the efficiency is higher.
4) set the resonance point jump, cause the motor to run away from the resonance point, so fans do not breathe shock.
after much research, rehabilitation programs are as follows:
1.2 motor parameters and the drive's specifications
1) motor parameters
model rated power rated voltage rated current rated power factor
1400kw 6kv 168a 0.80
2) drive specifications
input voltage: three-phase ac rms 6kv ± 10%
input frequency: 50 ± 5hz
output voltage: three-phase sinusoidal voltage 0-6kv
output frequency: 0-50hz
frequency resolution: 0.01hz
acceleration time: according to process requirements set
q. deceleration: set according to process requirements
frequency setting mode: two low speed can be adjusted within the range of 0-50hz
fault diagnosis and detection: automatic detection, automatic positioning
net side power factor: 0.95 (at high speed)
overload protection: 150% (l allow minutes every 10 minutes), 180% immediate protection
degree of protection: ip21
humidity: 90% non-condensing
in december 2009, after about a week of construction, installation and commissioning of the electrical test and test run goes well, put into operation a successful, high-voltage inverter has been sustained and stable operation. high-speed operation 45hz, low speed 20hz.
after 1.3 running inverter, now becomes the main advantages:
1) stable, safe and reliable. the original is probably about 60 days must replace the bearings, each about a half-day shutdown required, enormous economic losses.
2) energy-saving effect is remarkable.
the following table shows the production conditions under essentially the same conditions, one day randomly selected frequency and data frequency all aspects of comparison:
inlet temperature outlet temperature conditions the line current into the line active stator temperature axis average temperature saving rate
frequency 10-30 ℃ 30-65 ℃ 120a 1147kw 90 ℃ 60 ℃ 34%
frequency 10-30 ℃ 30-65 ℃ 75a 749kw 88 ℃ 42 ℃
compared with the original frequency drive, fan efficiency stable in the ideal range, the motor greatly reduce energy consumption, save electricity up to 34%, after the frequency conversion transformation energy conservation effect is remarkable.
3) electric motor to achieve a true soft start, soft outage, the inverter to the motor of sine wave current without harmonic interference, reducing the number of failures of the motor. simultaneously, the drive to set the resonance frequency jumps to avoid the resonance point in the long run the fan, the fan working smoothly, reducing fan bearing wear and prolong the motor and fan life and maintenance cycle and improve the utilization efficiency of the fan.
4) inverter protection function itself, compared with the original protection, more protection, more sensitive, greatly enhanced motor protection.
5) with the drive field signal seamless interface to meet the needs of production. built inverter plc, field signal access and flexible. drive converter according to the position of the automatic high-speed, low-speed running back and forth.
6) ability to adapt to voltage fluctuations.
7) during acceleration greatly reduces noise, weakens the noise pollution. because it is not regularly removable bearings, reducing oil pollution of the environment, so that the wind room scene environment has greatly improved.
