Air compressor power saving transformation principle:
First, the principle and effect of energy conservation We know that with the method of adjusting the motor speed can also adjust the air supply. As the air compressor is basically a constant torque load, adjusting the air supply volume with the variable frequency speed regulation method can basically make the motor output power proportional to the rotation speed (air supply volume), and achieve a good power saving effect. The power usage of the two regulation methods is shown in Figure 1.
We use ABB inverter with vector control function to make the motor provide the torque needed to meet the load at low speed. At the same time, the automatic energy-saving mode of ABB inverter can make the motor run with the minimum current under the load torque requirement, achieving better power-saving effect.
The effect brought by the constant pressure air supply frequency conversion control system is as follows:
Figure 1 Power-flow curve diagram (1). The outlet valve is completely closed, and the air outlet valve is used to adjust the air supply method to avoid wasted energy. Instead, the inverter adjusts the speed of the motor to adjust the gas flow, so that the power output of the motor is basically proportional to the flow demand (as shown in FIG. 1), and the motor is always operated with high efficiency to achieve significant power saving effect. For example, when the gas consumption is 50% of the rated air supply, the electricity saving rate can reach 40% or more;
(2) Using the energy-saving mode of the inverter, the motor can be operated with the highest efficiency at light loads, reducing unnecessary power consumption;
(3) According to strict EMS standards, high-efficiency PWM inverter uses high-speed and low-consumption IGBT to reduce harmonic distortion and motor power loss.
(4) It can make the current when the motor is started and loaded rise gently without any impact; it can make the motor achieve soft stop, avoid the harm caused by the anti-generated current, and it is beneficial to prolong the service life of the equipment; avoiding the current peak value Power company's fine;
(5) After adopting the variable frequency control system, the pressure of the gas in the gas supply pipeline can be monitored in real time, so that the pressure of the gas in the gas supply pipeline can be kept constant, and the production efficiency and product quality can be improved;
(6) As the motor operates in a high-efficiency state, the power factor is high, the reactive power loss is reduced, and a large amount of electric energy is saved (as shown in Fig. 2).
(7) Save the original release valve system, and if necessary, participate in the adjustment to enhance the reliability of the system.
In short, after adopting the constant pressure air supply intelligent control system, it will not only save 30-40% of the power cost, extend the service life of the compressor, but also achieve the purpose of “constant pressure air supply†and improve the production efficiency and product quality.
Second, the air compressor frequency control system description (a), an overview of the air compressor constant pressure air supply intelligent control system is composed of inverter, pressure sensor, programmable controller (PLC) control unit, software control unit and other components. According to the pressure value of the air compressor outlet detected by the pressure sensor, the control system adjusts the calculation through the programmable controller (PLC) and the inverter adjusts the working state of the compressor motor, while precisely controlling the pressure at the outlet of the air compressor. ,Prolong the life of the compressor system, and greatly save energy.
(II) Product Features
1. Realize the soft start of the compressor, no peak current, stable start;
2, significantly reduce the noise of the compressor system;
3, automatic control, simple and efficient, reliable and self-protection, without special care;
4, smooth operation, extend the life of the compressor system, reduce maintenance;
5, to ensure constant supply pressure, improve the quality of the supply;
6. Save a lot of energy:
7. Save the original soft-start system. The frequency-to-power frequency switching function of the control system can switch the compressor motor to the original soft-start system power frequency work when the frequency conversion control system fails to ensure that the compressor unit can work normally.
Third, the transformation program When the air compressor starts, there is a small amount of stagnant air pressure inside, start and acceleration and deceleration requires the inverter to respond quickly, so we use ABB inverter. The adjustment method adopts closed-loop automatic adjustment, and the control system detects the pressure signal value of the air compressor outlet according to the pressure sensor. After the signal conversion of the A/D analog digital conversion unit, the single unit is adjusted by a programmable controller (PLC) and a frequency converter. The speed of the compressor motor ensures that the motor is output with minimal power. While controlling the pressure accurately, realize the soft start of the electrical machinery and lengthen the service life of the compressor. When the frequency converter and PLC fail, they automatically switch to the original soft start cabinet power frequency power supply operation to ensure the normal operation of the compressor. The transformation plan is shown in the figure. The system block diagram is shown in Figure 6.
Fourth, case analysis
1, the configuration of the selection of air compressor is an important plant equipment, must ensure that the normal operation of 24 hours a day. The number of air compressors: 1 with 1 equipment, power: 55KW. In order to ensure the reliability of the transformed control system and the compressor group, the pressure of the air supply can be easily set according to the requirements, and the human-machine interface is provided. The frequency, current, voltage, power and other parameters of the motor are visually displayed and the energy-saving effect is achieved. At a glance, and the original unit performance and energy saving rate has been greatly improved.
The above is the pressure setting interface for water supply or air supply
We chose ABB inverters, Mitsubishi PLC and other imported accessories. ABB frequency changer main performance characteristic:
(1) Using torque calculation software control to ensure accurate torque control over the entire frequency range;
(2) High-speed microprocessors and DSPs are used to greatly increase the response speed;
(3) When the line voltage drops, there is automatic voltage regulation function (AVR), which can maintain high starting torque;
(4) Its automatic adjustment method makes the steps of frequency converter and motor parameter adjustment automatic;
(5) Automatically calculate the optimal acceleration/deceleration time according to the motor load and braking requirements;
(6) Energy-saving mode: It will automatically select parameters so that the motor can automatically save energy and run at minimum current to meet the requirements of load torque, so as to achieve the purpose of energy saving;
(7) PM smart power module reduces noise during motor operation.
2. Main materials and project expenses No. Name Specification Model Unit Quantity Brand
1 55KW Frequency Converter ACS510-01-124A-4 Table 1 Beijing ABB
2 Intelligent Fuzzy Controller KC-A55×1 Set 1 Kang Can Technology
3 man-machine interface MD204L 1 human-machine electronics
4 Mitsubishi Controller FX Series 1 Mitsubishi
5 A/D Module FX Series 1 Mitsubishi
6 Communication Modules FX Series 1 Mitsubishi
7 Buttons and Buttons φ22 Batch of 100 Million
9 Indicators φ22 Batch 1 Jiangyin
10 Distribution cabinet 2000×650×450 1 Nanjiang
11 pressure sensor with gauge pressure 1 Huashui
12 Air Switch ABE203B 175A Only 1 LG
13 AC Contactors GMC-100 160A 2 LG
14 AC Contactor GMC-65 100A 1 LG
15 AC Contactor GMC-32 50A 1 LG
16 Thermal Relays GTH-85 55A 2 LG
17 Mechanical Chain AR-9 1 LG
18 Mechanical Chain AR-100 1 LG
19 Cable 25~50mm2 Roll 1 Cheng Tian Tai
20 Sensor Shielded Cable Volume 1
21 Control Line Volume 2
22 Bridges Batch 1
23 Accessories Batch 1
3. Investment Return Analysis The monthly electricity consumption of your company's single air compressor is about:
55KW×24 hours/day×30 days/month×0.8 (average load ratio)=31680KWH
The energy saving rate of the air compressor can reach: between 20-30%, the average monthly value is: 25%; the price of electricity is 0.75 yuan/KWH:
Air compressor electricity savings per month: 31680KWH × 25% × 0.75 yuan / KWH = 5940 yuan
Keysun Technology Limited , http://www.powersupplychina.com