Research On Control Loop Performance Assessment Based On ARMA Model

The performance of industrial control system may degradation after running for a period of time,which is due to the change of operating conditions,generalized controlled and so on.How to obtain the performance information of the control system from the daily operation data of the production process,timely diagnose and improve the operation performance of the control system,that attract the attention of the field operators.Diagnose the change of system performance and optimize the control loop with poor performance through performance evaluation tools,which is the purpose of the performance evaluation of the control system.In this way,only the control loops with poor evaluation result need to be adjusted,which greatly reduces the work intensity of the staff.In this paper,based on the thermal power unit control system,a method based on ARMA model is proposed to evaluate the regulating performance of the controller.Firstly,time series analysis is carried out to establish ARMA model,and the system unit impulse response curve is calculated by its time domain characteristics.Evaluate the control system performance through graphical indicators,and deterministic performance indexes of the system such as response time can be obtained directly,then judge the system response sluggish/aggressive under the current controller adjustment.And the minimum variance index is calculated to quantitatively analysis of the current system performance.In order to have a full understanding of the control system performance,this paper combines this two performance evaluation methods for the comprehensive performance analysis of the control system,and the parameter optimization of the controller is given for the control loop with poor performance.The feasibility and effectiveness of the proposed method are verified by Simulink simulation model.Performance evaluation system software is designed through the GenSystem platform and Golden monitoring configuration platform.The thermal power unit control loop informations,process operation data and evaluation result are displayed in the evaluation interface in real time,and the historical values are saved.The evaluation software can monitor the loop running performance in real time,diagnose the direction for the performance degradation of the control loops with poor performance,and the corresponding controller parameter optimization suggestions are given.The software communicates with SIS database of thermal power plant,and the performance evaluation method based on ARMA model of this paper is applied to engineering practice.The correctness of the method is verified by field data.