Detection method of small flow based on gray correlation method

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.