Kelu CL2700 high-voltage inverter design and application in Roots blower 1. Necessity of high-voltage frequency conversion transformation of vertical kiln Roots blower The Guizhou Jiulong cement vertical kiln Roots blower is a winding asynchronous motor. The original operating mode is full-speed operation of the motor power frequency, and the required air volume is adjusted by the outlet vent valve Because of the limited power grid capacity of the company, the motor is not allowed to start at full voltage. The motor is started by the rotor series resistance. After the start, the start resistance is automatically shorted. The motor runs at full speed, but it is found that the outlet vent valve adjustment method exists after commissioning The following drawbacks: 2. The adjustment of the outlet vent valve is unscientific, uneconomical, and wasteful of resources. Although the use of the vent valve adjustment is simple in structure and low in investment, it is obviously inappropriate today when the awareness of energy saving is increasingly strengthened. In the early stage of the construction of the cement plant, due to subsequent possibilities From the perspective of expansion and operation safety, the margin of the motor and the fan is relatively large, and the phenomenon of the big horse-drawn carriage is serious. In fact, the rated current of the motor is 40A, and the actual operating current of the motor is only about 28A. The adjustment of the vent valve artificially releases the air pressure and volume of the air duct, and a large amount of energy is wasted by the vent valve. Today, with the increasing shortage of energy, it is obviously outdated, and energy-saving transformation is imperative. 3. When the motor is running at full speed, the motor bearings and other mechanical parts are seriously worn. In addition, because it is a rotor-wound asynchronous motor, the carbon brush on the slip ring of the rotor is also very serious when the rotor is running at high speed. The replacement cycle is short and the equipment Large amount of maintenance. 4. The start-up process is complicated. The rotor series resistance start-up method is accompanied by many secondary circuits, which requires a large amount of maintenance, but the use efficiency is not high, but it is indispensable. The start-up method is a backward process. In summary, in order to completely change the existing process, we must improve from the source, that is, by changing the motor speed to adjust the fan speed, so as to achieve the purpose of adjusting the air volume, in order to meet the on-site process requirements. Curved Lcd Display,Curved Display,Ultra Wide-Color Curved Lcd Monitor,Curved Screen Shenzhen Risingstar Outdoor High Light LCD Co.Ltd , https://www.risingstarlcd.com
1. The adjustment response of the outlet vent valve lags behind, the adjustment speed is slow, and the adjustment accuracy is low. Often, the required air volume is not controlled in place, which affects the production process requirements on site.
1. Cascade speed regulation: The advantage is that the slip power can be recovered, so the speed regulation efficiency is relatively high, but there are also many problems. It is not suitable for the existing rotor-wound asynchronous motor. The starting process is complicated and the starting current is large. The speed regulation range is limited, the response is slow, the power factor and efficiency are low, it is difficult to achieve cooperation with PLC and DCS and other control systems, the harmonic pollution is large, and there is greater interference to the power grid.
In addition, by using a proprietary PWM control method developed independently, the output voltage harmonics can be further reduced by 1 to 2% compared with other similar methods.
In order to improve the reliability of the system, a certain output voltage margin is considered in the entire frequency conversion speed regulation system, and a bypass circuit is added in each power unit. When a power unit fails, it can automatically monitor the failure and start the bypass circuit, so that the unit is no longer put into operation, and the program will automatically calculate and adjust the algorithm so that the output three-phase line voltage is still completely symmetrical. Operation is not affected in any way. This control method is at the international advanced level and domestic leading level, it will greatly improve the reliability of the system and the stability of operation.
CL2700 series high-voltage frequency conversion speed regulation system can also realize the feedback energy automatic limiting function.
When the number of unit failures exceeds the set value, the system can automatically switch to power frequency operation.
The rectifier transformer has perfect temperature monitoring function.
The unique design of the power cabinet air duct, the main heating components are close to or in the air duct, the heat dissipation effect is good, and the overload capacity of the system is ensured.
The interface is rich and can be connected with a variety of automation equipment and systems to meet the different needs of various scenes. Special interfaces can be customized.
With local and remote operation functions, the monitoring function can be realized remotely through DCS;
Maintenance is simple, all units are interchangeable and there are few spare parts.
1. Inverter parameters
Frequency conversion operation Frequency conversion speed regulation 10.5kV 11A 30.27Hz 4609kW.h 44.53%
Energy conservation is China's basic national policy. The state has formulated a “Special Plan for Energy Conservation in the Medium and Long Termâ€. To implement this plan, the National Development and Reform Commission recently launched ten key energy-saving projects. The cement industry, which is a large energy consumer, is the focus of national macro-control. It is also a key industry for energy saving. Through various measures, if the electricity consumption per ton of cement produced can be controlled within 100KW.h, calculated according to China's annual cement output of 1.2 billion tons, if it reaches the energy saving target, it can save millions of tons of coal every year. It saves tens of billions of electricity and reduces exhaust emissions, which is conducive to protecting the environment and reducing corporate costs. The frequency conversion transformation of the high-pressure roots fan of the shaft kiln of Guizhou Jiulong Cement Plant achieved the effect of saving electricity and improving the process, and achieved a complete success. At present, in China, the cement industry is relatively slow compared to other industries such as metallurgy and power. If most of China's cement manufacturing enterprises can reasonably and deeply tap their potential, then there is reason to believe that China's It will be bluer, the water will be clearer, and the bright future of an energy-saving harmonious society will surely be displayed in front of us!
Kelu CL2700 high-voltage inverter design and application in Roots blower
Second, the choice of speed control mode At present, the main speed control methods of domestic high-power high-voltage asynchronous motors are as follows: cascade speed regulation, internal feedback cascade speed regulation, hydraulic coupler speed regulation, frequency conversion speed regulation, etc.
2. Internal feedback speed regulation: Internal feedback speed regulation is developed on the basis of cascade speed regulation. The advantages are all the advantages of cascade speed regulation. The volume is small. The disadvantages are: the need to replace the special motor, and the slip ring is not easy to handle. In the event of an accident, although the frequency-sensitive varistor is used for starting, the startable current is still large, which has a great impact on the motor and the power grid, the speed range is limited, the input power factor and efficiency are low, and a large number of thyristor inverters are derived from the motor High-order harmonics cause aging of the motor's insulation, which can easily cause torque ripple of the motor, additional heat and noise pollution. The cables need to be thickened and the motor surge cannot be eliminated.
3. Hydraulic coupler speed regulation: the speed regulation range is limited, the high speed lost slip is about 3% -5%, the low speed slip power loss is greater (1-speed ratio), up to 15% of the rated transmission power, Because the efficiency is proportional to the speed, the efficiency is extremely low at low speed, the precision is low, the operation cannot be switched, the maintenance is complicated, and the cost is large.
4. High-speed frequency converter speed regulation: Due to the use of advanced power electronic technology, computer control technology, modern communication technology and high-voltage electrical, motor drive and other comprehensive fields of scientific technology, it has advantages that other speed control methods can not match.
3. Kelu CL2700 series high-voltage frequency conversion speed control system technical advantages
1. High-efficiency, pollution-free, high power factor CL2700 series high-voltage variable frequency speed regulation system uses a high-high scheme of power units connected in series, using a multi-winding high-voltage phase-shifting transformer, the current flowing in the secondary winding is once When superimposed on the side, a current waveform very close to a sine wave is formed. After actual testing, when running at 50 Hz, the grid side current harmonics <2%, the motor side output voltage harmonics <1.5% (even at 40 Hz, still <2%), the efficiency of the complete set> 97%, the power factor> 0.96 . It fully meets the requirements of IEEE 519-1992 for harmonic content of voltage and current.
2. Advanced bypass operation of faulty units (professional core technology)
3. High-performance control technology CL2700 series high-voltage variable frequency speed control system is the first to implement simple vector control technology, which can achieve constant torque rapid dynamic response, and has acceleration and deceleration adaptive functions, that is, according to the actual changes in operating conditions parameters , Automatically adjust the acceleration and deceleration time, reach the set speed quickly without exceeding the maximum allowable current; At the same time, the system can automatically identify the motor speed, the user can ignore the current operating state of the motor, the motor does not need to stop running Directly start, accelerate, decelerate or stop the motor.
4. High-reliability control power supply can realize external 220V power supply and high-voltage power supply auxiliary power supply dual-circuit power supply automatic switching, and at the same time equipped with UPS, even if both power supplies fail, the control system can still work long enough to control the entire system Safely stop, issue an alarm, and record all status parameters during a fault.
Using high-speed optical fiber communication can effectively avoid electromagnetic interference.
Strong resistance to grid voltage fluctuations, the system can work normally when the grid voltage fluctuates in the range of -15% to + 15%; for the power unit, it can work normally when the voltage changes in the range of -25% to + 20% .
5. Other features Strong fault self-diagnosis ability, monitoring all main parameters and interface signals in the system.
10.4 inch LCD Touch Screen man-machine interface, simple operation, friendly, and rich display content.
4. The specific implementation plan and process of the transformation project
Advantages: When the high-voltage inverter fails, there is an obvious power-off point, which can ensure personal safety, and can manually put the load into the power frequency grid operation
Disadvantages: when the high-voltage inverter fails, the original resistance starting device cannot be automatically switched from the frequency conversion to the power frequency site. When the high-voltage inverter fails, the high-voltage input cable of the inverter can be directly switched to the resistance starting device. The operation is simple and fast.
5. Reformation effect
CL2700-10-0700-9QY 10kV 700kVA 0.96 46A
560kW 10kV 40A 32A 0.83 594
Power frequency operation vent valve 10.5kV 28A 50.00Hz 8310kW.h
Frequency conversion soft start small low fast low
After the frequency conversion transformation of the shaft kiln Roots fan, the indirect effect obtained is also very obvious, because the frequency conversion speed control system often runs at about 30 Hz, the rotation speed of the motor and fan is reduced, the shaft temperature of the motor and fan is reduced, the noise is reduced, and the overall maintenance The period is greatly shortened. The operator can conveniently adjust the running frequency of the motor through the monitoring interface on the remote control box side. The frequency resolution of the high-voltage inverter is accurate to 0.01 Hz, and the adjustment is timely and the adjustment accuracy is high.
6. Summary