CN-121979305-A - PID parameter setting method of steam generator liquid level control system

CN121979305ACN 121979305 ACN121979305 ACN 121979305ACN-121979305-A

Abstract

The invention relates to the technical field of automatic control of industrial processes, and particularly discloses a PID parameter setting method of a steam generator liquid level control system, which comprises the steps of firstly collecting a high-frequency pressure fluctuation signal of a water supply pipeline, and extracting energy data of a characteristic frequency band through frequency spectrum transformation; then, a real-time confidence index representing the tiny leakage probability is generated by analyzing the deviation degree and the change trend of the energy data relative to the reference value; finally, parameters and logic of integral action in the liquid level PID controller are dynamically adjusted according to the index, namely, conservative parameters for inhibiting false water level are adopted when the confidence coefficient is low, integral accumulation is frozen and damping water supplementing bias is applied when the confidence coefficient is middle set, and the integrator input is switched into a flow deviation signal based on material balance and positive parameters are adopted when the confidence coefficient is high.

Inventors

ZHANG HOUJI
HOU JUNCHENG
ZHANG XUEQIN
LI ZONGBING
CUI ZHICHEN

Assignees

青岛法罗力暖通温控技术设备制造有限公司

Dates

Publication Date: 20260505
Application Date: 20260107

Claims (10)

1. A method for tuning PID parameters of a steam generator level control system, comprising the steps of: S1, collecting an original high-frequency pressure fluctuation signal in a water supply pipeline of a steam generator; S2, carrying out real-time spectrum transformation and feature separation on an original high-frequency pressure fluctuation signal, and extracting spectrum energy data of a preset frequency band related to abnormal fluid disturbance; s3, generating a real-time confidence index representing the tiny leakage probability of the pipeline based on the continuous deviation degree and the time variation trend of the spectrum energy data and the preset reference energy data under the corresponding working condition; S4, dynamically adjusting parameters of integral action in a liquid level control loop according to the magnitude of a real-time confidence coefficient index, wherein the adjustment mode comprises the steps of adopting a first group of preset conservative integral parameters for suppressing false water level when the real-time confidence coefficient index is lower than a first threshold value, freezing accumulation of integral action and applying a forward water supply flow bias when the real-time confidence coefficient index is higher than the first threshold value but lower than a second threshold value, switching an input signal of integral action into a flow deviation signal calculated based on material balance when the real-time confidence coefficient index is higher than the second threshold value, and adopting a second group of preset positive integral parameters for coping with leakage; s5, calculating the deviation between the liquid level measurement signal and the liquid level set value by utilizing the integral parameter dynamically adjusted in S4, and generating a final control signal by combining the proportional and differential actions to adjust the water supply flow; Wherein the integral parameters are conservative integral parameters and positive integral parameters.
2. The method for setting PID parameters of a steam generator level control system according to claim 1, wherein S2 comprises: preprocessing an original high-frequency pressure fluctuation signal, wherein the preprocessing comprises low-pass filtering and downsampling based on a preset cut-off frequency to obtain a signal to be analyzed; Performing time-frequency domain transformation on the signal to be analyzed to obtain transformation coefficient sequences corresponding to sub-bands with different frequencies; Calculating the signal energy of each sub-band in a preset frequency band based on the transformation coefficient sequence; and carrying out weighted summation on the signal energy of each sub-band to obtain the spectrum energy data.
3. The method for setting PID parameters of a steam generator level control system according to claim 2, wherein the calculating the signal energy of each subband in the predetermined frequency band based on the transform coefficient sequence specifically comprises: calculating the product of the absolute value of the transformation coefficient and a preset energy weight factor for each transformation coefficient in the transformation coefficient sequence to obtain the absolute value of the weight coefficient; for each sub-band, accumulating and summing absolute values of all weighting coefficients in the sub-band to obtain a preliminary energy value of the sub-band; judging whether the preliminary energy value of each sub-band is larger than the historical background noise energy baseline value of the sub-band, if so, taking the difference value of the exceeding part as the final signal energy of the sub-band, and if not, setting the final signal energy of the sub-band as 0.
4. The method for setting PID parameters of a steam generator fluid level control system of claim 1, wherein the generating a real-time confidence indicator that characterizes the probability of a small leak in a pipeline comprises: Calculating the difference value between the spectrum energy data and the reference energy data under the same working condition by using the spectrum energy data in the sliding time window to obtain the current energy deviation degree; calculating the change rate of the current energy deviation degree in the sliding time window as the energy change rate; comparing the current energy deviation degree with a first deviation threshold value, comparing the energy change rate with a pre-trained positive energy change rate threshold value, and starting weighted accumulation of an internal state quantity only when the current energy deviation degree and the first deviation threshold value continuously exceed the respective threshold value for a preset duration; and mapping the accumulated result of the internal state quantity through a preset nonlinear function, and outputting a real-time confidence index.
5. The method for setting PID parameters of a steam generator fluid level control system according to claim 4, wherein the mapping the accumulated result of the internal state quantity by a preset nonlinear function comprises: Acquiring an accumulation result of the internal state quantity as an input value of the nonlinear mapping; The input value is input into a preset nonlinear function, and the nonlinear function is divided into three continuous intervals in a definition domain, wherein the nonlinear function output in the first interval grows slowly, the nonlinear function output in the second interval grows rapidly, and the nonlinear function output in the third interval grows slowly again and approaches to a saturation value; normalizing the output of the nonlinear function to enable the output of the nonlinear function to fall within a numerical range of 0 to 1; and outputting the normalized numerical value as a real-time confidence index.
6. The method for setting PID parameters of a steam generator level control system according to claim 1, wherein the employing a first set of preset conservative integral parameters for suppressing false water levels comprises: Inquiring a corresponding conservative integral parameter set from a preset operation point-parameter mapping table according to the current operation point of the steam generator; Calculating interpolation weights between the set of conservative integration parameters and a set of more conservative alternate integration parameters according to the magnitude of the real-time confidence index; And linearly interpolating the two sets of parameters by using interpolation weights to obtain the integral parameter value of the current practical application.
7. A method of PID parameter tuning of a steam generator fluid level control system as claimed in claim 1, wherein said accumulating of freeze integration and applying a forward feedwater flow bias comprises: locking and storing the historical accumulated value of the integral action; Starting from an initial value, the internal weighting coefficient is decreased to 0 according to a preset attenuation rate; Multiplying the part of the real-time confidence index exceeding the first threshold value with a preset bias reference value, Multiplying the internal weighting coefficient to obtain a dynamic forward bias value; The dynamic forward bias value is superimposed on the feedwater flow set point.
8. The method for tuning PID parameters of a steam generator fluid level control system of claim 1, wherein said employing a second set of predetermined positive integral parameters for leakage comprises: Switching and using a second set of preset positive integration parameters for the leakage to the input signal for the integration action specifically includes: starting a signal transition process, and mixing the liquid level deviation signal and the flow deviation signal according to a preset time-varying proportion during the period to form a transition input signal; resetting the historical cumulative value of the integration to 0 in the first control period after the signal transition process is completed; and dynamically reading and applying corresponding positive integral parameter values from a preset curve according to the amplitude of the real-time confidence index exceeding the second threshold.
9. The method for setting PID parameters of a steam generator level control system according to claim 1, wherein S5 specifically comprises: Calculating the deviation between the liquid level measurement signal and the liquid level set value with the selected proportional action parameters to obtain proportional action quantity, calculating with the integral parameters adjusted by S4 to obtain integral action quantity, and calculating with the selected differential action parameters to obtain differential action quantity; synthesizing the proportional action quantity, the integral action quantity and the differential action quantity according to a preset superposition rule; and outputting the synthesized total amount as a final control signal.
10. The method for setting PID parameters of a steam generator level control system according to claim 9, wherein the synthesizing the proportional action amount, the integral action amount, and the differential action amount according to a preset superposition rule specifically comprises: Acquiring a real-time confidence index; according to the numerical value of the real-time confidence index, respectively searching real-time dynamic synthesis weights corresponding to the proportional action quantity, the integral action quantity and the differential action quantity from a preset weight mapping relation; Multiplying the proportional action amount, the integral action amount and the differential action amount with the corresponding real-time dynamic synthesis weights respectively to obtain weighted proportional components, integral components and differential components; Algebraic addition is carried out on the weighted proportional component, integral component and differential component to obtain the total synthesized quantity.

Description

PID parameter setting method of steam generator liquid level control system Technical Field The invention relates to the technical field of automatic control of industrial processes, in particular to a PID parameter setting method of a steam generator liquid level control system. Background The liquid level control of a steam generator (such as a boiler, a nuclear power station steam generator and the like) is a core link for guaranteeing the safe and stable operation of the steam generator. Too high a liquid level can lead to steam carrying water and damage downstream turbine equipment, and too low a liquid level can expose a heating tube bundle to cause overheating and even tube explosion accidents. Therefore, maintaining the liquid level near the set point is a critical control objective. In the existing steam generator liquid level control, the integral leading PID controller adopting fixed conservative parameters cannot be effectively distinguished because the characteristic of the initial signal of the false water level is similar to that of the true leakage, so that when the tiny leakage occurs, the controller can misjudge the false water level as the false water level to be restrained so as to continuously generate a reverse (water supply reduction) error control instruction, thereby forming a dangerous positive feedback channel for aggravating leakage and delaying response and seriously threatening the difficult problem of safe operation of the system. Disclosure of Invention The invention aims to provide a PID parameter setting method of a steam generator liquid level control system, so as to solve the problems in the background. The aim of the invention can be achieved by the following technical scheme: A PID parameter setting method of a steam generator liquid level control system comprises S1, collecting original high-frequency pressure fluctuation signals in a steam generator water supply pipeline; S2, carrying out real-time spectrum transformation and feature separation on an original high-frequency pressure fluctuation signal, and extracting spectrum energy data of a preset frequency band related to abnormal fluid disturbance; s3, generating a real-time confidence index representing the tiny leakage probability of the pipeline based on the continuous deviation degree and the time variation trend of the spectrum energy data and the preset reference energy data under the corresponding working condition; S4, dynamically adjusting parameters of integral action in a liquid level control loop according to the magnitude of a real-time confidence coefficient index, wherein the adjustment mode comprises the steps of adopting a first group of preset conservative integral parameters for suppressing false water level when the real-time confidence coefficient index is lower than a first threshold value, freezing accumulation of integral action and applying a forward water supply flow bias when the real-time confidence coefficient index is higher than the first threshold value but lower than a second threshold value, switching an input signal of integral action into a flow deviation signal calculated based on material balance when the real-time confidence coefficient index is higher than the second threshold value, and adopting a second group of preset positive integral parameters for coping with leakage; s5, calculating the deviation between the liquid level measurement signal and the liquid level set value by utilizing the integral parameter dynamically adjusted in S4, and generating a final control signal by combining the proportional and differential actions to adjust the water supply flow; Wherein the integral parameters are conservative integral parameters and positive integral parameters. The invention further provides a further scheme that the S2 specifically comprises the following steps: preprocessing an original high-frequency pressure fluctuation signal, wherein the preprocessing comprises low-pass filtering and downsampling based on a preset cut-off frequency to obtain a signal to be analyzed; Performing time-frequency domain transformation on the signal to be analyzed to obtain transformation coefficient sequences corresponding to sub-bands with different frequencies; Calculating the signal energy of each sub-band in a preset frequency band based on the transformation coefficient sequence; and carrying out weighted summation on the signal energy of each sub-band to obtain the spectrum energy data. The further scheme of the invention is that the method calculates the signal energy of each sub-band in the preset frequency band based on the transformation coefficient sequence, and specifically comprises the following steps: calculating the product of the absolute value of the transformation coefficient and a preset energy weight factor for each transformation coefficient in the transformation coefficient sequence to obtain the absolute value of the weight coefficient; for each sub-band, accumul