Control method of variable frequency lift pump based on liquid level adjustment

Abstract

The invention relates to a control method of a variable frequency lift pump based on liquid level adjustment. The control method comprises the following steps of: switching protection of a water pump during frequency conversion: firstly, forcibly lifting the frequency of a frequency converter to a set frequency value before switching the power frequency of the lift pump into a variable frequency; and variable frequency adjustment method of the lift pump for liquid level feedback control: adopting a constant water level PID variable frequency adjustment mode of absorption well water level tracking for the variable frequency adjustment control of the lift pump. Compared with the prior art, the invention has the advantages of solving the problem of current impact on the frequency converter due to load current break during the switching of the variable frequency pump, so that the service life of the frequency converter is greatly prolonged; meanwhile, the phenomenon of frequency converter damages caused by too great impact current is also avoided. The method has practicability in the aspect of switching control of a plurality of variable frequency pumps.

Description

technical field [0001] The invention relates to a control method of a frequency conversion pump, in particular to a control method of a frequency conversion lift pump based on liquid level regulation. Background technique [0002] The lift pump is a common equipment in residential water supply, waterworks, sewage treatment plants, water conservancy projects, etc. With the development of motor frequency conversion technology, the control of lift pump equipment has gradually increased from conventional start and stop to frequency conversion technology. To adjust the output power of the lift pump to achieve high efficiency and energy saving. [0003] Water pump frequency conversion speed regulation exists in the occasion of multi-pump combination operation. At present, when multiple frequency conversion pumps are automatically switched, because the moment when the water pump in operation is powered on, the motor current will rise instantaneously from no load to load, thus affec...

AI Technical Summary

Problems solved by technology

[0003] Water pump frequency conversion speed regulation exists in the occasion of multi-pump combination operation. At present, when multiple frequency conversion pumps are automatically switched, because the moment when the water pump in operation is powered on, the motor current will rise instantaneously from no load to load, thus affecting The frequency converter forms a current impact, which reduces the service life of the equipment and deteriorates the operating quality and environment of the variable frequency pump

[0004] Secondly, at present, the current liquid level feedback speed control method in front of the pump directly feeds back the current liquid level value, which will cause the variable frequency pump to be adjusted frequently, especially when the variable frequency pump is at the critical point of operation, it will cause the variable frequency pump to surge. Reduced service life of the pump