Henan Shenhuo Aluminum Industry Co., Ltd. Yongcheng Aluminum Plant has an existing capacity of 210,000 t/a of electrolytic aluminum, 7 sets of piston air compressors for normal production, model D-100/10-a, and its synchronous motor model: TK630 -12/1430i3 compressed air mainly meets the demand for wind in the electrolysis workshop, and the conveying demand of alumina dense phase and ultra-dense phase. Three shifts are used in the actual production process for production, 8:00 and 4 per day. The alumina is used for the dense phase transportation, and the zero shift does not carry the dense phase transportation. Therefore, the total gas consumption is changed. It is necessary to adjust the pressure with the actual production to ensure that the pressure in the pipe network often runs 4 air pressures at 0.6~0.7MPal3. Machine, compressed air pressure will be lower than 0.6MPa; run 5 air compressors, air pressure is higher than 0.7MPal3 to ensure normal production, must run 5 air compressors at all times, one will always be in a semi-unloading state, The electric energy of the air compressor generates a lot of waste. In order to save energy and adjust the air supply pressure of the air compressor, the frequency conversion of the synchronous motor of the air compressor is carried out in a one-to-three manner to realize the stepless speed regulation of the motor. The air compressor is running By adjusting the speed of the motor to adjust the compressed air output, while other air compressors are running at full load, 1 frequency conversion energy-saving retrofit solution, one to three air compressor frequency conversion transformation scheme, as shown in the transformation project, the speed control device is rated Voltage 10kV, rated power, aluminum equipment management.
The HARSVERT-VS10/45 high-voltage inverter bypass cabinet with 790kVA and rated current of 45A adopts one-to-three setting. The bypass switching device with high-voltage contactor is composed of three high-pressure contactors KM1, KM2 and KM3, and requires KM1 and KM2. And KM3 can not be closed at the same time, can only choose to run one, when the electrical interlocking frequency conversion operation is realized, QF is closed; when the power frequency is running, QF is disconnected, and the frequency conversion speed control device control system is still carried out according to the original power frequency operation steps. It adopts all-digital microcomputer control, and has two control modes: local monitoring and remote monitoring. 3Fig. One-for-three air compressor frequency conversion modification scheme 1.1 Air compressor operation mode Air compressor operation adopts “4+1†operation mode, ie Under normal circumstances, 4 air compressors operate at power frequency, 1 frequency conversion operation, the operating frequency of the inverter is set at 40~5OHz, and the air supply pressure is adjusted by adjusting the motor frequency to adjust the air supply pressure of the air compressor. When the adjustment mode is normal frequency conversion operation, the inverter outputs the voltage to the synchronous motor according to the preset logic. The synchronous motor starts. If the synchronous motor starts the inverter, it will not be full when it is close to the power frequency state. Production requirements, m automation application of variable frequency energy-saving and soft-start system requires manual power-on operation of another motor on-site, and then adjust the inverter motor until it meets the work; or manually switch the inverter air compressor to the power frequency manually. Then, the frequency converter starts another air compressor, FM 1.3 stop demagnetization function, when the frequency converter stops, the “stop†command is issued from the field to the inverter, the inverter drives the synchronous motor to decelerate to the stop frequency, then stops the output voltage and finally breaks in the field. The circuit breaker QF informs the excitation device to de-excitation by its auxiliary contact. When the de-excitation is completed, the excitation device power supply is turned off. 1.4 When the fault is encountered, the inverter immediately disconnects the circuit breaker QF while stopping the voltage output. Point to inform the excitation device to immediately de-excitation 131.5 frequency conversion of various protections (2) transformers allow overload capacity in line with IEC dry-type transformer overload guidelines and corresponding national standards (3) each power unit with three-phase input fuse protection 13 ( 4) The frequency conversion device has over voltage, over current, under voltage, phase loss, inverter overload, inverter overheating, motor overload Protection function overload protection: 120% of motor rated current, 1min per lOmin, over protection 13 overcurrent protection: overvoltage protection of inverter output current exceeding motor rated current: detecting DC bus voltage of each power module, if exceeded The inverter voltage protection is 115% of the rated voltage, which actually includes the protection against the positive fluctuation of the grid voltage. 13 Undervoltage protection: Detect the DC bus voltage of each power module. If it is lower than the undervoltage protection setting, the inverter Protection, in fact, includes protection against negative voltage fluctuations in the grid. 13 Overheat protection: Temperature detection is set in the cabinet of the variable frequency speed control system. When the ambient temperature exceeds the preset value, an alarm signal is sent; in addition, the main heating element , that is, the temperature detection is placed on the rectifier transformer and the power electronic power device. Once the limit temperature is exceeded (the transformer is 130 ° C, the power device is 80 ° C), the protection phase loss protection is set on each power module, when the inverter input side When the phase is lost, the system sends out an alarm signal and protects; when the fuse of the power module fuses out of phase, the system sends a warning letter. Fiber fault protection: When the connection fiber between the controller and the power module fails, an alarm signal is issued and protection 13 (5) specifies the exact location of the fault on the Chinese user interface, so that the user can take countermeasures. (6) The inverter device is isolated. Transformer temperature overheat protection (7) The switchgear of the upper port of the inverter must set the quick-break protection value according to 8~10 times of rated current to ensure that the excitation current is avoided. 2 Energy-saving analysis and transformation effect from November 20, 2009 At this stage of operation, the operation effect is good: (1) The power saving is based on the principle of energy saving of the fan and water pump. When the motor frequency is 40Hz, the motor speed is 400i./min. During the operation of the energy-saving air compressor, the motor frequency is always maintained. At 40~50Hz, the synchronous motor speed is between 400~500i7min. After the actual electrical metering, the power saving is about 35%. 13(2) Improve the grid side power factor The original motor is directly driven by the power frequency. The power factor is 0.85 at full load. ~0.92, the actual operating power factor is much lower than the rated value. After adopting the high-voltage variable frequency speed control system, the power factor of the power supply side can be increased to 0.95 or more, greatly reducing no The absorption of power further saves the running cost of the upstream equipment. (3) Reduces the operation and maintenance cost of the equipment. After the frequency conversion speed regulation is adopted, the energy is saved by adjusting the motor speed; the speed is reduced, and the front and rear support bearing of the air compressor crankshaft is lightened before the maintenance period. The operating life of the equipment is prolonged; the number of operations of the air compressor inlet and exhaust valves is reduced, and the service life of the air compressor is prolonged. In the process of using the frequency converter, it is only necessary to regularly remove the dust from the frequency converter without stopping the machine, thus ensuring the continuity of production from the actual transformation situation. After adopting the frequency conversion speed regulation, the running and maintenance costs are greatly reduced. (4) After the soft start function is modified by the high voltage frequency conversion, the motor realizes the soft start and soft stop, the starting current does not exceed 1.4 times of the rated current of the motor, and there is no impact on the power grid. The service life is extended over the entire operating range. The motor can ensure stable operation, low loss, normal temperature rise, and no abnormal vibration and noise. 13(5) Increased motor protection function Compared with the original system, the inverter has Flow, short circuit, over voltage, under voltage, phase loss, temperature rise, etc. (6) Enhancement system Operation reliability 13 high-voltage variable frequency speed control system adapts to the grid voltage fluctuation ability, the grid voltage fluctuates between -35% and +15%, and the system can operate normally. 3 Conclusion Air compressor high-voltage motor frequency conversion energy-saving renovation project is completed. The motor energy saving is 35%, and the equipment failure rate is reduced, and the maintenance cycle of the air compressor is extended. The frequency converter has a power frequency and frequency conversion manual change switch, so that the frequency conversion fault can be manually switched to the power frequency state operation, and the work is performed. Frequency and frequency conversion with interlocking device 13
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