Waterworks Water Supply System Transformer Variable Water Supply Patterns Applied Research

With the development of China's economy, the demand of water for living and working is accordingly keep growing. To meet the needs of water supply is definitely what we sought to guarantee. In addition, it is of great importance to figure out how to ensure the stability, reliability and energy saving economy of water service in the water supply system.This paper analyzed both the advantages and disadvantages of the two forms of water supply, constant pressure water supply and variable-pressure water supply. A more scientific and energy-saving form of variable-pressure variable-flow water supply is adopted. It set the water pressure of water supply network outlet as the controlled object, and designed a practical program for water supply system. Therefore, when the pump operate in a high efficient, practical and energy-saving way, it can not only guarantee the most appropriate water level of water tank, but also enable the water supply pressure to meet the demands of water supply.The paper analyzed the mathematical model of variable-pressure variable-flow water supply system, which is characterized by its nonlinearity and time delay. As the mathematical mode of controlled object is difficult to make accurately, it adopted the fuzzy control theory to control the water supply pressure after a brief introduction of this theory. It designed the fuzzy controller, and adjusts the output frequency of frequency converter through the fuzzy rule online. The flow of water supply outlet has a certain linear relation with the pressure. The pressure can be calculated by collecting the flow so as to be set as the given of pressure. It made a comparison between the real-time collected pressure and the given pressure, which can leads to the pressure difference and the change rate of pressure difference. And then it designed the fuzzy controller according to the pressure difference and the change rate of pressure different.The paper made an introduction of the PLC (Programmable Logic Controller) S7-300 of the Siemens and the programming software STEP7 of S7-300, and used it as control equipment, which is adopted for program designing of electrical diagram and PLC. It is known that frequency converter is very expensive. For saving costs, the paper made a detailed analysis of the principle of variable soft-start cycle, and proposed to control three pumps by one frequency converter. In order to manage a cycle frequency converter start. When the water demand is relatively small, only one pump is needed to meet the water needs. Since a pump may go wrong after long-hours working, it will change to another pump after the pump has worked for a certain period.In order to achieve a better full automation, it introduced the configuration software for monitoring and controlling the equipment and devices in the field, which focused on GE's iFIX configuration software, and designed the main image of water supply system by iFIX. In the main image, it can also alternative between variable frequency and power frequency operation of the pump. The image also shows the outlet pressure of pipe network, the operation state and the current frequency of frequency converter. Upper computer system can not only facilitate the staff to operate but also can identify immediately and make maintenance once it goes wrong, which naturally helps to save the labor.Compared with traditional ways of water supply, this system is superior for being energy saving and stable, what's more, it is automated and can saving the cost, which will certainly gain a bright future for practice.