【 Weak current College 】 low pressure in the water supply system of rational use of---Power By 【 China power house network 】

1. Tianjin jizhuangzi regeneration water plant water supply status: residential pumping station
Tianjin jizhuangzi regeneration water plant design, residential delivery pump water supply capacity is 3 million tons/day, primarily for residents of meijiang residential areas provide water users, community life, miscellaneous and King of water, landscape and water for cooling water and circulating water. Residential delivery pumping device type is used in double-suction pump, of which 4 model HV200-150-400/4P-55KW horizontal pump (2 sets of frequency control, 2-speed control, power to 55KW), 2 sets of model ESV-80-50-200/2P-18.5KW vertical pump (1 bed for Inverter control, 1 for speed control, power to 18.5KW). External water supply system for constant pressure water supply: due to many users at different moments in water demand, water-supply system for real-time changes to ensure constant pressure water demand, you need to pump and run through the adjustment of motor frequency inverter, change the motor speed to adjust volume, to maintain the network and constant pressure, (that is, users instantly increase water consumption, reduces the pressure pipeline, increase in frequency inverter motor rotation speed, feed water pump yield increase, so that the pipeline pressure to return to the set value. And vice versa. ) Guarantee that every user normal water.
　　
2. low voltage converter technical principles:
(A) speed is in the same workload can be a different speed to meet the requirements of the production process. In discussing the converter, the first of the formula:
n = (1- s ) n0 = (1- s ) 60 f1 / p (1)
Where: n: motor speed
N0: motor synchronous speed
S: motor slip
P: motor windings pole
Through the formula (1) shows that changing the motor speed has three possibilities:
A. pole speed
B. frequency control
C. variable slip speed
(2) frequency conversion technology
In recent years, the frequency conversion technology development at present mainly uses very quickly, as shown in the figure below:
Inverter is SCR controllable Silicon rectifier and the inverter. Rectifier first 50 Hz AC transformation to DC, and the inverter changes to frequencies, voltage RMS also adjustable, three-phase AC induction motor supply. This can be the motor of the stepless speed regulation, and mechanical properties with hard.
　　
3. a reasonable energy utilization of the frequency converter
(A) send water pump flow and the speed and frequency of relations:
Q1 = ( n1 / n) Q (2)
Where: n: pump rated speed
Q: the rated flow of the pump
N1: pump below the rated speed of a speed
Q1: and speed n1 corresponding effluent flow
Based on n = 60f1 (1-s)/p (3)
Available Q1 = (f/f1) Q (4)
Where: f 1: power frequency (50HZ)
F: and motor a frequency corresponding to the n1 speed
(Ii) send water pump power and speed, frequency of relations
N1 = （n1 / n）3 N (5)
Where: N: pump rated power
N1 N1: and the speed corresponding to the power
According to formula 3 and formula (5) the available power and the relationship between the frequency:
N1 = （n1 / n）3 N = (f / f1 )3 N (6)
(3) send pump lift and speed, frequency of relations:
H1 = (n1 / n )2 H (7)
Where: H: pump rated lift
H1: and n1 corresponding head
By formula (3) and (7) the formula can be drawn:
H1 = (f / f1 )2 H (8)
(Iv) use a converter to achieve the purpose of concluding and energy-saving measures:
(1) actual running process we use a small pump (18.5KW), in the flow of 0m3/h ~ 80 m3/h, the corresponding frequency variation in 25HZ ~ 43HZ, according to the formula (6), calculation of small pump power changes between 2.3 ~ 11.76KW; and use a large pump (55KW), in the flow of 0m3/h ~ 80 m3/h, the corresponding frequency in 30HZ ~ 34HZ, according to the formula (6) calculation, the minimum frequency pump power consumption is not lower than 11.88KW. Thus, when outside the network need small flow of water, (such as winter or during the night and constant pressure water supply), we can run a small pump, lower power consumption.
(2) by the formula (6) and (8) we may receive and send water pump power and lift:
N1 / N = （f / f1）3 (9)
H1 / H = (f / f1 )2 (10)
N1 /N = (H1 / H )3/2 (11)
By formula (11) can be seen, when the lift is low, i.e. the network voltage value decreases, the inverter power consumption will be reduced, when our water supply to water users at the same time teach low probability, especially at night, we can supply the appropriate constant value set lower, will reduce the energy consumption of the pump.
　　
4. the inverter in the city water supply system in the rational use of Outlook
The modern city water supply system, adjust the frequency pump outlet flow, instead of the traditional through to manually adjust the water valve to open degree, is the modern human technological advancements, while also reducing the power consumption of pump delivery, reducing the cost of running water, strengthenedExternal supply of stability, reliability, and from the electrical point of view the water plant to "low consumption efficient" has realized the leap-forward development. How to make the most of inverter to run on water plant is of great significance.