Application of frequency converter in water equipment control system

The frequency conversion and voltage stabilization water supply equipment control system adjusts the output frequency through the measured pipe network pressure, after calculation by the built-in PID regulator of the frequency converter, to achieve constant pressure water supply of the pipe network. The frequency overlimit signal of the frequency converter can timely notify the PLC to switch the frequency conversion pump logic. To prevent the occurrence of water hammer, the start and stop of the pump will link its outlet valve.

Selection description of frequency conversion and voltage stabilization water supply equipment

The water supply system of frequency conversion and voltage stabilization water supply equipment is mainly composed of frequency conversion control cabinet, pressure sensor, water pump, etc. The frequency conversion control cabinet is composed of circuit breaker, frequency converter, contactor, intermediate relay, PLC, etc.

According to the process requirements, it is recommended to use SW200 series frequency converter. SW200 series frequency converter is a high-performance frequency converter launched by SOWAKAM in combination with many advanced production and manufacturing processes. It has a wide voltage range, excellent speed control and torque control characteristics, complete protection functions, flexible programming capabilities, and high reliability. Main technical data of variable frequency voltage stabilizing water supply equipment:

Power range: 2.2-500kw

Power supply voltage: AC 160~264V/AC 304~528V;

Standard RS-485 interface allows the inverter to be easily connected to the computer;

Built-in PID;

Protection characteristics: overcurrent protection/overvoltage protection, undervoltage protection, 

overheating protection, short circuit protection, grounding protection, undervoltage buffer, motor under/overload protection, etc;

CE certification.

Application scope of variable frequency voltage stabilizing water supply equipment

The system can be used for production and domestic water, as well as hot water supply, constant pressure spraying and other systems.

 a. It can be widely used in industrial enterprises, domestic and production water supply systems and enterprise self-prepared and renovation projects, water plants, living quarters and fire water supply systems.

b. It can be used for constant pressure, voltage conversion, cooling water and circulating water supply systems in various occasions.

c. It can be used for sewage pumping stations, sewage treatment and sewage lifting systems.

d. It can be used for agricultural irrigation and drainage, garden sprinklers, waterscapes and music fountain systems.

e. It can be used for water supply and fire protection systems in hotels and large public buildings.

PID control principle of variable frequency voltage-stabilized water supply equipment

According to the feedback principle: to maintain a physical quantity unchanged or basically unchanged, this physical quantity should be compared with the constant value to form a closed-loop system. To keep the water pressure constant, the water pressure feedback value must be introduced to compare with the given value to form a closed-loop system. However, the controlled system is characterized by a nonlinear and large inertia system. Now the method of combining control and PID uses fuzzy control when the pressure fluctuation is large to speed up the response speed; PID is used to maintain static accuracy when the pressure range is small. The algorithm can be realized by adding PLC and intelligent instruments, and the PLC programming can realize the switching between the working frequency and variable frequency of the pump. This method is feasible and low in cost.