Water Supply GNP is indispensable in the life of an important part. Traditional large area of water supply, water pollution and easy, more investment in infrastructure, but the main drawback is the constant pressure can not be maintained, resulting in some of the equipment is not working properly.

    Frequency control technology is a new AC motor stepless mature technology, with its unique excellent control performance is widely used in the speed control, especially in the water supply industry. Because of the special needs of production safety and water quality of water supply pressure has strict requirements, and therefore frequency control technology has been more in-depth applications. Constant pressure water supply advanced technology, constant pressure, easy to operate, reliable, energy saving, high degree of automation in the water pumping station can perform the following functions:

    (1) maintain a constant pressure;
    (2) control system manual / automatic operation
    (3) multiple pumps automatically switch operation;
    (4) system sleep and wake up when the external water stops, the system is in sleep mode, automatic wake up when there is demand for water;
    (5) Online tuning PID parameters;
    (6) pump and line protection detection alarm, signal display.

    The actual pipe network pressure feedback after comparison with a given pressure, when there is insufficient pressure in the pipe, the inverter increases the output frequency, the pump speed to accelerate, increasing the water supply, forcing the pipe network pressure rises. Conversely pump speed slows down, reduce the amount of water supply pipe network pressure drop, maintaining constant pressure water supply.

Frequency characteristics and analysis:

    Water users generally are dynamic, so the water supply insufficient or excess supply situation have occurred. The imbalance between the supply of water and concentrated reflection on the water pressure, the more water and less water, the pressure is low; less water and more water, the pressure. To maintain a constant water pressure, you can maintain a balance between water supply and water that the water supply for a long time too much, too little water came from water, thus improving the quality of the water supply.

    Water Supply System for users is very important. In the production of domestic water supply, if the water supply for any reason without water pressure is low or short-term, may affect the quality of life, and even affect the survival of safety, such as when the fire broke out, or if the lack of water pressure or anhydrous supply, not rapid fire may causing significant economic losses and casualties. Therefore, the use of the water area Zheng Yi pressure water supply system, capable of generating greater economic and social benefits.

    With the development of power technology, frequency conversion technology is improving daily, with frequency control as the core intelligent water control system to replace the previous high water tank and pressure tank and other water equipment, a smooth start, starting current limit at rated current, thus avoiding the impact on the starting grid; average pump speed is reduced, and thus extend the life of pumps and valves, and other things; you can eliminate water hammer effect when starting and stopping. Its stable and secure operating performance, simple and convenient operation, as well as a full array of capabilities, will allow water to achieve water-saving, energy-saving, save manpower, and ultimately achieve the purpose of high efficiency operation.

Frequency of applications:

    Usually in the same way water supply system, set up multiple commonly used in pumps, multiple large water pump full of water supply to open one or two hours. When frequency control constant pressure water supply, it is used in two ways, one is all the water pump with an inverter; Second, each pump is equipped with a converter. The latter method based on the feedback pressure signal, automatically adjust the output frequency through the PID operation, change the motor speed, and ultimately achieve the purpose of the pipe network constant pressure on a closed loop, it is relatively simple, but the cost is high. The former method is low cost, poor performance than the latter, but more complex control procedures, is the future direction of development.

PID control principle:

   Based on the feedback principle: in order to maintain a physical constant or substantially constant, should lead this constant comparison with the physical, form a closed loop system. We want to maintain a constant pressure, and therefore must be introduced pressure feedback value and given value, thereby forming a closed-loop system. However, the characteristics of the controlled system is nonlinear, inertial systems, PID control, and a combination of methods, pressure fluctuations in the use of fuzzy control, in order to speed up response time; smaller when using PID in the pressure range to maintain static accuracy. This is done by adding PLC intelligent instrument may now when the algorithm, while switching to the programming of the PLC when the current pump frequency and frequency between. Practice has proved that this method is feasible, but cost is not high.

    To maintain a constant pressure of the water network, according to the feedback theorem on the pipe network management system installed pressure transducer as feedback element, since the water supply system piping length, large diameter, pressurized pipe network are slow, so system is a big delay system, PID regulator is not easy to directly control, and participation by way of PLC control system to achieve the control regulation.