Development Of Embedded Intelligent Multiple-pressure Water-Supply Control System

With rapid development of economy, people's living standards improve continuously in recent years, and the demand for water supply increase fast. So it consumes more and more electric energy to supply water. Due to the improvement of public awareness of energy conservation and climbing energy prices, it becomes an inevitable trend to reduce energy consumption of water system by making use of advanced control technology and automatics. The purpose of this paper is to explore how to design a water supply system which consumes less enegy than constant-pressure water supply system. Because the performance of water supply system mainly depends on the control unit, it becomes the core goal to develop a more advanced, energy saving control system.By analysing the work pattern, merits and drawbacks of conventional water supply system, it confirms that constant-pressure water supply system basing on converter technique is more advanced in energy conservation, workload and construct space. After the anolysis about the working curve of delivery lift and flow rate of pump, this paper delves the hydraulic loss during water flows, and suggests improving from constant-pressure water supply system to multiple-pressure pattern. In this pattern, if the demand of water exceeds the capability of a variable frequency pump, system works in constant-pressure mode; if demand is less than a pump's capability, it works in the multiple-pressure mode which makes energyefficiency of system to be promoted largely.For getting real-time responses in multiple-pressure water supply control system, Freescale's 16-bit high-performance micro-controller (MCU), which has a co-processor, is choosed as the core of real-time control unit. On the one hand it samples the information of water's pressure and quality throuth high-resolution AD channels; On the other hand, by using high-performance DA, it regulates the work frequence of frequency-converter which controls rotate speed of variable frequency pump. Accordingly the whole water supply system forms a typical negative feedback closed-loop control system, and it lightens the workload of maintenance personnel since it can work automatically in the case of right parameters.There are many shortcomings in present water supply control system, such as inconvenient system maintenance, intuitive Operator Interfaces, and no access-authentication function. To solve these problems, we make use of high-performance embedded processor PXA270 (CPU) to process the task of Human-computer interaction. It displays the status information of system in a 5.6 inch LCD and gets settings throuth a touchpad attached to the LCD. By this way, it makes maintenance work simple and convenient. Furthermore, it reserves a network interface for the development of remote control service in the further.Except taking on respective work, MCU and CPU communicate with each other continually through Modbus, and constitute the Embedded Intelligent multiple-pressure Water Supply control System corporately. In 3 months of debugging and verification inside simulation environment of laboratory, its humanness has been improved by optimizing system setting. After that, this water supply system has been used in a town water works of Ningbo for 3 months, and the working records prove this system could conserve energy obviously and energy consumption was 18 percent less than constant-pressure water supply on a year-on-year basis.In consideration of our nation's large population and developed industry, there are fairly huge market demands for water supply control system.Therefore, if the multiple-pressure water supply system can be promoted widely, it will produce substantial economic benefit and make contribution to carbon society.