Dynamic filter estimate method of conductivity-order resistance capacitance system parameters

Abstract

The invention provides a dynamic filter estimate method of conductivity-order resistance capacitance system parameters, and belongs to the field of solution electrical conductivity soft-sensing technology. The dynamic filter estimate method is characterized in that measurement of the conductivity is converted into parameter estimate of first-order equivalent resistance-capacitance system considering lead distribution capacitor influence. The method particularly includes steps: setting up a parameter state space model on the condition that a resistance-capacitance parameters to be estimated in an hour-segment are constant approximations, adopting sine drive signals in certain frequency to excite a resistance capacitance system, based on sampling signals obtained through high-speed analog / digital (A / D) from the sine drive signals and systematic response signals, starting a Kalman filter constructed according to the parameter state space model, recursively calculating N steps in each hour-segment, namely obtaining estimate values of solution resistors and lead distribution capacitors in each hour-segment. The dynamic filter estimate method has the advantages of being strong in interference resistance, capable of obtaining real-time estimate of the resistance-capacitance parameters in high accuracy, and suitable for industrial online application of conductivity measurement.

Description

technical field [0001] The invention belongs to the technical field of solution conductivity soft measurement, and relates to a method for estimating the parameters of a conductivity first-order equivalent resistance-capacitance system, especially when considering the influence of lead distributed capacitance, based on the measured system excitation and response data, A method for reconstructing the estimated values ​​of the parameters of the resistance-capacitance system through dynamic filtering. Background technique [0002] Solution conductivity is an important electrochemical parameter, and the research and exploration of its measurement methods are constantly deepening. Literature "ZHONG C Q, HAN H L, ZHANG L Y, et al. Summary of conductivity measurement[C]. IEEE Proceedings of the 6th World Congress on Intelligent Control and Automation, June, 2006, 6: 5106-5110" Counter electrode conductivity The methods of measurement and electromagnetic conductivity measurement ar...

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Problems solved by technology

For the conductivity first-order equivalent resistance-capacitance system model considering the influence of lead distributed capacitance, the literature "Cui Pengfei, Zhang Liyong, Zhong Chongquan, Li Dan. Numerical simulation of multi-frequency square wave excitation resistance-capacitance decoupling soft measurement. Journal of Instrumentation , 2010, 31(1): 154-160 "Using AC square waves of multiple frequencies to excite the resistance-capacitance system respectively, a mathematical model between the excitation signal, the response DC voltage signal and the two parameters of resistance and capacitance is established, through nonlinear The least squares method estimates the resistance and capacitance parameters, which can weaken the influence of various uncertainties in the measurement, but its optimization solution uses the steepest descent method, which requires iterative calculations, and there is a problem of uncertain iteration times

In order to solve this problem, the patent document "Zhang Liyong, Zhong Chongquan, Li Dan, Zhou Kaidi, Ling Jingwei. Linearized Real-time Estimation Method for Conductivity Resistance-Capacitance Network Parameters (ZL 201010549653.7)" first offline the above excitation signal, response Multivariate polynomial fitting is performed on the mathematical model between the DC voltage signal and the two parameters of resistance and capacitance. During online measurement, the multivariate polynomial model fitted offline is used to establish an overdetermined equation system. Based on the principle of linear least squares, the finite The real-time estimation of resistance-capacitance parameters can be obtained by step arithmetic operation and radical operation of quartic equation solution, but the multivariate polynomial fitting in this method will inevitably lose certain accuracy

In addition, the patent document "Zhou Kaidi, Zhang Liyong, Ling Jingwei, Zhong Chongquan, Li Dan. Resistor-capacitance decoupling soft measurement method based on amplitude-phase characteristic detection (ZL 201010173466.3)" aims at considering the influence of lead distributed capacitance. The equivalent resistance-capacitance system model adopts sinusoidal signal excitation, uses the multi-point sampling of the response signal to fit its function form, and then obtains the amplitude-phase characteristic parameters of the resistance-capacitance system, and then obtains through the relationship between the amplitude-phase characteristics and the resistance-capacitance parameters In this method, the amplitude and phase characteristic parameters of the resistance-capacitance system are still obtained using the nonlinear least square method, and the optimization solution uses the steepest descent method, and there is also the problem of uncertain iteration times.

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