Research And Implementation Of Resonant Frequency Detection Method For Dual Channel Steam Humidity Measurement System

The role of steam turbines in power plants is crucial.The operating efficiency and safety performance of steam turbines operating under steam humidity conditions will be seriously affected by the size of steam humidity.Therefore,measuring the humidity of steam in a steam turbine with high accuracy and real-time in an actual environment is beneficial to reducing economic losses and improving work efficiency.This article analyzes the working principle of measuring the humidity of the cavity by the resonant cavity,discusses the relationship between the accuracy of the humidity measurement of the humidity and the resonant frequency of the resonant cavity,and studies and implements the detection method of the resonant frequency of the vapor humidity measurement system.Based on the theoretical analysis of the amplitude and phase characteristics of the S-parameters of the resonant cavity,this paper studies the detection method of the resonance frequency,and implements a measurement system based on the amplitude characteristics to detect the resonance frequency.A scheme for detecting the resonance frequency based on the phase characteristics is proposed.This paper theoretically deduces the mathematical relationship between resonance frequency and steam humidity;uses HFSS software to build a three-dimensional model of a cylindrical cavity for electromagnetic simulation,and obtains the phase and amplitude characteristics of the S parameter,which provides a theoretical basis for the study of the detection method of resonance frequency In order to improve the measurement accuracy,the dual-channel measurement method is adopted,and the STM32single-chip microcomputer is used as the control system,and the hardware circuit construction and software design are completed by combining the microwave circuit and the FPGA chip;the FPGA is used to perform frequency measurement with equal accuracy,and the resonance frequency measurement system is implemented,and The measurement was performed in a laboratory environment,and the results showed that the measurement error of the system was below 10 Hz.Then based on the theory of the S-parameter phase characteristics of the resonant cavity,the relationship between the phase difference and the resonant frequency is derived.In order to eliminate the interference of noise on the reflected signal of the resonant cavity,the phase information of the signal is extracted using a double correlation algorithm,andMATLAB is used to perform the second phase The simulation experiments of the recorrelation algorithm verify the feasibility of detecting resonance frequency based on phase characteristics,and a resonance frequency detection scheme based on phase characteristics is constructed.