Anti-interference signal processing method and system based on vortex shedding flowmeter

Abstract

The invention provides an anti-interference signal processing method and system based on a vortex shedding flowmeter. The method comprises the steps that 1, sampling signals of a sensor in the vortex shedding flowmeter are obtained; 2, fast Fourrier transformation is performed on the sampling signals to obtain corresponding frequency domain information, and interference signals and flow signals are distinguished by means of frequency variance; 3, a corresponding flow value is obtained through K-coefficient conversion. The invention further provides the anti-interference signal processing system based on the vortex shedding flowmeter. By adopting the FFT algorithm, period atlas analysis is performed, and the flow signals are extracted from the collected time-domain signals; even when the flow signals are weak and the interference signal frequencies are overlapped, a wave trap set with adjustable trap width and depth is adopted, strong interference signals inside a power density spectrum are eliminated, the signal to noise ratio and lower measurement limit of the vortex shedding flowmeter are increased, and the precision is higher.

Description

technical field [0001] The invention belongs to the technical field of flow detection, and in particular relates to a processing method and system based on an anti-interference signal of a vortex flowmeter. Background technique [0002] The vortex flowmeter entered the country relatively early, due to the characteristics of the vortex itself: 1) When the Reynolds number meets certain conditions, the vortex signal has good linearity, repeatability, and high accuracy. Usually, the liquid measurement accuracy is ±0.5%~±1%, the gas measurement accuracy is ±1%~±1.5%, because the vortex street is generally only used as a control instrument and does not participate in the measurement, so this accuracy basically meets the needs of users; 2) The vortex sensor has no moving parts It relies on the vibration of the fluid itself for measurement. It has strong reliability, high precision and long service life. It can accurately measure the instantaneous flow of the medium in a wide flow r...

AI Technical Summary

Problems solved by technology

The disadvantages are: the processing method is too simple, inflexible, low in intelligence, and not easy to adjust to meet the needs of changes in the field environment

For example: when the vibration of the measuring pipeline has a great influence, a little pipeline vibration will be reflected in the output signal of the sensor, because the vortex street is realized according to the principle of fluid vibration mechanics, so the vibration of the pipeline causes the fluid to vibrate, the vortex flowmeter If the piezoelectric crystal is too sensitive, the vibration signal will be reflected as a flow signal by mistake. On the contrary, if the sensitivity of the piezoelectric crystal decreases, the weak flow signal will be lost, so the vibration signal will inevitably be mixed into the flow signal, destroying the flow signal. The waveform of the flow signal causes the threshold circuit to make an error when shaping the analog signal, output more or less pulse waveform, and affect the measurement accuracy

Due to the characteristics of the vibration generator of the vortex street sensor, the signal has a tailing phenomenon, that is, the generated vortex passes through the piezoelectric crystal, and the piezoelectric crystal induces a strong signal, and the vortex moves away from the piezoelectric crystal, and the induced signal weakens. The phenomenon has a certain periodicity, which causes the threshold circuit to lose part of the signal waveform due to the unreasonable threshold.

Therefore, the traditional vortex flowmeter is quite weak in anti-interference ability, which leads to great restrictions on its use in the field

Images