Key words: configuration software PLC virtual water pump
Water supply industry, water distribution, booster pump station frequency control energy-saving technological transformation, after the operation, generally found in the use of the following problems:
1, in the case of water and meet the needs of the user to ensure that the water pressure, when the pump opening in parallel, with little or no saving saving pump; a pump running speed, little or no saving power saving.
2, when the conditions point, the pipe network parameters and other changes, and in the pumping station system to meet the conditions of work conditions, the speed control system often appear unstable operation, resulting in energy saving can not maintain the lowest unit power consumption value.
In view of the use of the water supply industry, many people blindly regard the VVVF equipment as the energy-saving equipment. In fact, they are not clear about the VVF technology at all and there is no accurate measure of the power-saving effect. In this regard, this article discusses the parallel pump, the unit with a reasonable operation and the use of speed control mode, the use of force control configuration software + PLC control technology to solve the pump energy-saving economic operation of the quantitative problem.
First, the minimum energy consumption of the parallel combination of pump running and speed control mode of control theory
1, control theory
Under the conditions of process parameters (flow and pressure) and equipment parameters (pump, motor and speed governor) of the pump station system, the least square method is used to find out the functional relationship between HQ and the parallel pump group characteristic curve Fitting method, automatically find a set of minimum energy consumption with running and speed control mode, that is, optimizing the pump combination (running with a reasonable pump operating conditions stable operation in the high efficiency range). Of course, the optimal pump combination does not necessarily mean that each pump can achieve the optimal result. In this case, it means the overall effect of the optimized combination of pumps in a pump station. It can vividly indicate that each of the optimized combinations Pump combination of programs as a pump, pump combination scheme we call the virtual pump, and a virtual pump under a certain pressure and flow, using the least squares theory to calculate the virtual pump characteristic equation and characteristic curve as a standard , Find out the range of the virtual pump efficient area. When the operating point of the "virtual water pump" is not operating in the high-efficiency area, the control system can automatically adjust the operating conditions of the variable frequency pump according to the similar theorem of the pump speed regulation and the equivalent efficiency principle so that the dynamic operation of the virtual water pump Of the working point in the high-efficiency area, then the unit flow minimum energy consumption.
In order to make the working condition point of the "virtual water pump" after the speed regulation run in a high efficiency area, the characteristic curve of the "virtual water pump" after speed regulation can pass the set parameters (flow and pressure) according to the similarity theorem and the equivalent efficiency principle Point, this point is the "virtual water pump" the best condition point.
Second, technical design and implementation
1, pumping station process and control process
1.1 pumping station process
Dongzhuang with pumping station of our company adopts direct pumping method to distribute water to a DN800 pipeline , with a final distribution flow of 2100m3 / h and an outbound pressure of 0.39MPa. The main equipment are: 2 Japan MITSUTISHI F series inverter; 4 centrifugal pump, each pump equipped with a water outlet valve, a hanging solenoid valve; 2 vertical submersible pumps (drainage); 2 Vacuum pump (water pump vacuum hanging water). In addition, there are system-related automation instrumentation and more. Starting from the goal of saving energy and reducing consumption, the final pump set of water pump station is optimized and matched with speed control scheme.
Water pump in the clear water level of more than 1.8 meters when the water level for the self-filling; 1.8 meters below the need for vacuum hanging water. The number of pumps to open and close stops, according to the water level of the pool, service pressure and flow parameters automatically optimize the combination and the pump running status through the PLC's I / O interface promptly sent to the strength control configuration software real-time database so that the duty monitor at any time Pump operation; drainage pump water level under the pits, vacuum pumps according to the requirements of the vacuum hanging water to determine the open, stop pump. In the electrical circuit, high and low voltage switchgear closures are manually operated, power and instrument data records are automatically transmitted, on duty personnel can see from the display in time for each virtual pump unit flow power consumption values and other parameters. 1.2 pumping station control process
Pump control within the pump station, the site can be manually controlled, semi-automatic control, automatic control, run pump failure, the standby pump automatically open. Set the parameters (flow, pressure) of "virtual water pump". The display also shows the theoretical HQ characteristic curve and pipe network characteristic curve of "virtual water pump". According to the theoretical unit flow power consumption value corresponding to each "virtual water pump", select the "virtual water pump" scheme and output the selected scheme. Before the pump is started, the system will automatically check the state of the clear water tank, the pump stop status, the pump non-fault status, the pump running status, the inverter non-fault status and the valve position status signal. If it is not normal, The signal is normal, turn on the speed control pump and the constant speed pump in sequence, and automatically open the corresponding outlet valve. After the "virtual water pump" is operating normally, the "virtual water pump" theoretical characteristic curve can be monitored from the display screen and the actual dynamic state of the "virtual water pump" If the real-time unit flow power consumption of the "virtual pump" exceeds the theoretical unit flow power consumption, the system will make a sound , Light alarm signal, promptly notify the duty staff, with local control by the duty manual control to adjust, so that the "virtual water pump" operating point in the high-efficiency area. If any of the above signals are not correct, the pressure and flow in the pipe network can not be switched on even if the requirements are met. At the same time, an alarm signal is issued. In addition, each pump running real-time current exceeds its normal rated current, and delay 8 seconds, the fault alarm signal, and emergency stop pump. If the pump fails to press the program, the alarm. Each pump motor failure, can automatically shut down the corresponding valve, and issued a fault alarm signal, while the standby pump put into operation. PLC received the closure of the pump command, first shut down the corresponding outlet valve, the pump stopped running. Drainage pump control logic and high and low voltage power distribution monitoring parameters controlled by the PLC alone.
2, software design and implementation
Third, the application effect
June 2000 After the measured data statistical analysis, we found that the use of independent control frequency conversion control technology, parallel pump operation, less energy-saving, with no use of frequency conversion equipment similar. April 2002 After the use of configuration software + PLC + VVVF control technology transformation, the pumping station system to meet the working conditions, automatic frequency conversion system is stable, the long-term energy saving effect to maintain the lowest unit power consumption than the original frequency After the transformation of equipment saving about 30.
Fourth, conclusion
In summary, in the water supply industry, the use of self-controlled frequency conversion equipment is energy-saving, after practice, we believe that only the application environment, the control object and by accurate theory how much energy-saving potential, and then use what kind of automatic control program to transform energy-saving The greatest potential, and the system is stable and reliable, energy-saving effect to maintain long-term stability, is what we really want to achieve with the current information technology to transform the traditional control process.
references:
① training materials preparation group control configuration software instructions. Beijing three-dimensional control Technology Co., Ltd. 1999.07.
② training materials writing group OMRON PLC Programming Manual. Shanghai OMRON Automation Co., Ltd. 1997.05.
③ Jiang Jishen eds. Water supply industry automatic control system Hohai University Press 1999.12.
④ Liu Chichia. Establishment of Pumping Station Economic Operation Plan. Pump Technology, 1998.02.
⑤ Yu Ming, Fan Shu Chang. Centrifugal pump operating conditions parallel to determine the point. Pump Technology, 1999.02.
⑥ Han Dehong Sun Wenshen. Establishment of Shenzhen Special Economic Zone Raw Water System Dispatching Model. China Water Supply Review for Fifty Years, 1999.
Automatic Chicken Feeder,Poultry Feeder,Automatic Poultry Feeding Machine
Main Feeding System Co., Ltd. , http://www.nsfeedingsystem.com
没有评论:
发表评论