First, the characteristics of frequency conversion constant pressure water supply
1. Energy saving can save 20%-40% energy and achieve green electricity.
2. Small footprint, low investment and high efficiency.
3. Flexible configuration, high degree of automation, complete functions, flexible and reliable.
4. The operation is reasonable. Because it is soft and soft stop, not only can the water hammer effect be eliminated,
And the average torque and wear on the motor shaft are reduced, reducing maintenance and maintenance costs.
And the life of the pump is greatly improved.
5. Since the frequency conversion constant pressure speed regulation directly from the water supply, reducing the secondary pollution of the original water supply method,
Prevent the source of infection of many infectious diseases.
6. Through communication control, unattended operation can be achieved, saving manpower and material resources.
Second, the principle of energy conservation
According to the working principle of the water pump, the flow rate of the water pump is proportional to the speed of the water pump (motor). The lift of the water pump is proportional to the square of the speed of the water pump (motor). The shaft power of the water pump is equal to the product of the flow rate and the lift, so the shaft of the water pump The power is proportional to the third power of the speed of the pump (the shaft power of the pump is proportional to the third power of the power supply frequency). According to the above principle, the power of the water pump can be changed by changing the speed of the water pump.
Basic flow formula:
QâˆN HâˆN2 KW=Q*HâˆN3
The above Q represents flow, N represents rotational speed, H represents lift, and KW represents shaft power.
For example, if the power supply frequency is reduced from 50HZ to 45HZ, then P45/P50=(45/50)3=0.729, that is, P45=0.729 P50;
If the power supply frequency is reduced from 50HZ to 40HZ, then P40/P50=(40/50)3=0.512, that is, P40=0.512 P50.
The water pump is generally considered according to the maximum operating conditions of the water supply system at the time of design. However, the water system may not be able to reach the maximum amount of water during actual use. Generally, the valve is used to increase the resistance of the system to throttle the flow. Loss of power to the motor is caused, and the use of the inverter allows the system to operate smoothly and stably. The water supply can be adjusted by changing the rotation speed, and the investment can be recovered by lowering the speed. From the figure below we can see the comparison of the three flow control methods.
100KW three flow control methods of power consumption measured comparison table:
flow%
Inverter shaft power KW%
Input valve control
Shaft power KW%
Output valve control
Shaft power KW%
Ideal shaft power KW%
50
15
60
84
12.5
60
25
64
89.5
21.6
70
38
68
95
34.3
80
55
72.5
99.5
51.2
90
79
84
103.5
73
100
108
106
107
100
Many motor drive devices have problems such as large margin, low work efficiency, large power consumption, large starting current, and large working noise. And continuously affect the economic efficiency of enterprises, and investment in the inverter can fundamentally solve these problems, under normal circumstances, can completely improve the process conditions, and the investment recovery period does not exceed 10 months.
Third, the main application of frequency conversion speed constant pressure water supply equipment
1, high-rise buildings, urban and rural residential communities, enterprises and other domestic water;
2. All kinds of industries need constant pressure control of water, cooling water circulation, thermal network water circulation, boiler replenishment, etc.
3, the central air conditioning system;
4, water plant booster system;
5, farmland irrigation, sewage treatment, artificial fountain;
6, a variety of fluid constant pressure control system.
IV. System composition of frequency conversion constant pressure water supply equipment
The frequency converter is the core part of the entire frequency conversion constant pressure water supply system. The block diagram of its system is shown in Figure 1.
In the figure, the pump motor is the output link, and the speed is controlled by the inverter to achieve variable flow constant voltage control. The frequency converter accepts the PID controller signal to control the speed of the pump. The pressure sensor detects the pressure in the pipe network and transmits the signal to the PID controller. The PID controller adjusts the frequency of the inverter to control the speed of the pump and realizes a closed-loop control. system. Because the easy-to-energy converter has its own PID adjustment function, it is not necessary to use an external PID regulator to make the adjustment more stable.
V. Application and setting steps of Eenergy EDS2000 series inverter in frequency conversion constant pressure water supply system
Since Eenergy EDS2000 series inverters have a built-in PID regulator, some manufacturers use the built-in PID adjustment of Eenergy EDS2000 series to reduce the overall cost, and Eenergy EDS2000 series inverters also serve the majority of users due to its ideal sleep function. Greatly improved energy efficiency. The basic wiring diagram is as follows, and the function settings are as follows.
Parameter number
Features
Parameter value
F3.00
Closed-loop operation control selection
1
F3.01
Given channel selection
1
F3.02
Feedback channel selection
1
F3.03
Digital voltage setting
0.00
F3.04
Digital pressure setting
0.00
F3.05
Minimum given
0.00
F3.06
The amount of feedback corresponding to the minimum given amount
0.00
F3.07
Pressure value corresponding to F3.06
0.00
F3.08
Maximum given amount
100.0
F3.09
Maximum amount of feedback corresponding to the amount of feedback
100.0
F3.10
F3.09 corresponding pressure value
1.000
F3.11
Proportional gain KP
0.050
F3.12
Integral gain KI
0.050
F3.13
Differential gain
0.000
F3.14
Sample period T
0.10
F3.15
Deviation limit
2.0