Online detection method for operating efficiency of variable frequency water supply system

Abstract

The invention provides an online detection method for operating efficiency of a variable frequency water supply system, comprising the steps of establishing a mathematic model and constraint conditions among output power, frequency disturbance quantity and hydraulic pressure variable quantity to form a mathematic model needed by the online detection of the operating efficiency of the water supply system; carrying out frequency small signal disturbance under a stable working condition, setting an initial value of shaft output power, carrying out iterative computations to calculate the shaft output power in the stable state according to the output power mathematic model, so as to solve the efficiency of the variable frequency water supply system. According to the online detection method, the online output power detection can be realized, a flow sensor is not needed, time and cost needed by system installation and debugging are saved, the system structure is simpler, and the system cost is lower. By using the online detection method, the lower efficiency fault caused by the low-frequency running of a motor and a frequency converter are effectively avoided, the service life of the system is prolonged, the reliability of the system is improved, and reliable guarantee can be provided for the safe and efficient running of a water pump motor.

Description

technical field [0001] The invention belongs to the field of mechatronics measurement and control, and in particular relates to an online detection method for the operation efficiency of a frequency conversion water supply system, and is especially suitable for detection of the operation efficiency of a water pump of a frequency conversion water supply device for an air pressure tank. Background technique [0002] As a high-energy-consuming general-purpose machine, water pumps are widely used in various fields of industrial and agricultural production and residents' lives. The annual electric energy consumed by water pump units accounts for more than 21% of the country's total electricity consumption, and accounts for 30% of production costs in water supply enterprises. %~60%. Even if the efficiency of water pumps and water pump systems is only increased by 1%, it will bring huge benefits to my country's energy saving and environmental protection, and 30% to 50% of the elect...

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Problems solved by technology

[0004] 1. Flow sensor scheme: that is, flow detection is realized by installing a flow sensor at the water outlet of the pump; the flow sensor detection mechanism commonly used is mainly the impeller type, but the following three situations will lead to flow detection accuracy and reliability performance indicators not tall:

[0005] ①When the flow rate of water supply is high, the solid debris in the water will hit the impeller, causing the impeller to be deformed and damaged, causing the moment of inertia of the whole mechanism to be unbalanced, resulting in the failure of flow detection or greatly reducing the accuracy and data reliability; ②The water quality is polluted When it is acidic or alkaline, it will seriously corrode the impeller mechanism, which will also lead to the imbalance of the moment of inertia of the whole mechanism, the failure of flow detection or the greatly reduced accuracy and data reliability; The relevant electromagnetic mechanism acts to convert the rotation signal of the impeller into electrical signals of different frequencies

[0007] ⑴ High requirements on the hardware and software of the control system

[0008] (2) Due to the long-term operation of the system, the liquid medium constant, motor parameters, and frequency converter parameters are affected by environmental factors and aging causes change, causing large changes in the operating characteristics of the system, resulting in poor measurement accuracy and reliability;

[0009] (3) Since the water supply system runs continuously for a long time, once the water pump fails, only the motor that is strictly matched with the controller can be used instead of other types of water pump motors, which leads to high operation and maintenance costs of the system and poor practicability and applicability

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