Performance Evaluation And Self-healing Of Complex Control Loops

Complex loop control is a widely used control strategy in the field of process control.The cascade control loop,feedforward-feedback control loop and uniform control loop are widely used.Its stable and effective operation is an important factor to ensure safe and stable process production.At the initial stage of process operation,these control loops have good control performance.However,due to the change of working conditions,the lack of maintenance and effective monitoring methods,the control performance of the complex control loops gradually can not meet the control requirements.Therefore,in order to maintenance the performance of the complex control loops,the research of comprehensive evaluation methods of the control loop performance and the realization of the control loop performance self-healing have been in this thesis.Firstly,a control loop performance evaluation and self-healing method is proposed based on comprehensive performance index,and evaluates the control loop performance according to the evaluation indexes:stability index,tracking index and consumption index.According to the characteristics of the complex control loop,the corresponding evaluation criteria are established.When the control performance is poor,internal model control method is applied to optimize the controller parameters online.Adjusting sensitivity function and complementary sensitivity function are introduced to improve the robustness and tracking performance of the controller,and the self-healing of the control loop performance is realized.The application results have verified feasibility and effectiveness of the proposed method.Secondly,an adaptive controller performance evaluation and self-healing method based on ISE-TSV index and a new neurodynamic(ZNN)model is proposed.Firstly,the control performance of the complex control loop is evaluated by using ISE(Integal Squared Error)and TSV(Total Squared Variation)indexes.Secondly,an adaptive controller performance self-healing method based on the ZNN model is applied to optimize the controller parameters to recover the control performance.Finally,the controller performance evaluation and self-healing software has been developed to realize the performance evaluation and real-time monitoring of the control loops.And B-S Web based information release system has been developed to achieve remote monitoring and maintenance of complex control loops.The application results have shown the maintenance efficiency is improved and the automatic control rate and the effective application rates of the control loops are improved obviously.