A small flow detection method based on gray correlation method

Abstract

The invention discloses a detection method of small flow based on a gray correlation method. The method includes: establishing mathematical model and restraint conditions for flow, frequency disturbance and water pressure change to form a mathematical model suitable for online detection of small flow; performing frequency small signal disturbance under the stable state, and detecting system flow by a gray correlation algorithm and gray correlation criterion; classifying the flow value detected online to determine whether a system is in the small-flow state or not. The method is high in detection speed, high in reliability, high in practicality and effective in protecting a motor and a converter from the failure low efficiency caused by operation under low frequency in the condition of small flow; the life of the system is prolonged, and the reliability of the system is improved; safe, efficient operation of the water pump motor is reliably guaranteed.

Description

technical field [0001] The invention belongs to the field of mechatronics measurement and control, and specifically relates to an online detection method for small flow operation based on a gray correlation method, and is especially suitable for detection and protection of small flow operation of water pumps in frequency conversion and constant pressure water supply devices for air pressure tanks. Background technique [0002] The head characteristics and pipe resistance characteristics of the constant pressure variable frequency water supply system have an important impact on the performance of the water supply system. The head loss increases, resulting in increased system energy consumption and low efficiency. Among them, "small flow" refers to when the opening of the faucet is very small or the faucet is not completely closed and the water consumption is small or close to zero due to the dripping of the pipe. This situation is called the small flow situation of the freque...

AI Technical Summary

Problems solved by technology

[0006] (1) The following three situations in the impeller detection will lead to low flow detection accuracy and reliability performance indicators: ① When the water supply flow rate is large, the solid debris in the water quality will hit the impeller, causing the impeller to be deformed and damaged, causing the entire mechanism to fail. The unbalanced moment of inertia will lead to the failure of flow detection or the greatly reduced accuracy and data reliability; ②When the water quality is polluted and becomes acidic or alkaline, it will seriously corrode the impeller mechanism, which will also lead to the unbalanced moment of inertia of the entire mechanism, the failure of flow detection or the accuracy and The reliability of the data is greatly reduced; ③The impeller flow detection drives the impeller rotation through the flowing liquid, thereby driving the relevant electromagnetic mechanism to move, and converting the rotation signal of the impeller into electrical signals of different frequencies

[0010] ⑴ High requirements on the hardware and software of the control system

[0011] (2) Due to the large amount of data collection, processing and solution of system feature quantities, as well as similarity analysis with benchmark reference feature quantities, the program load is large, the processing time is long, and the detection speed is slow;

[0012] (3) During the long-term operation of the system, the motor parameters, inverter parameters, etc. are affected by environmental factors and change due to aging, which causes a large change in the operating characteristics of the system, resulting in poor measurement accuracy and reliability, and misjudgment of the control system. ;

[0013] ⑷Because 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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