Active Disturbance Rejection Control Of Marine Refrigeration System

The marine refrigeration system is a necessary auxiliary equipment to ensure ship transportation and operation.Its stable operation and strong anti-disturbance ability are of great significance for reducing ship energy consumption.In the actual operation process,the marine refrigeration system is faced with the time-varying disturbance in the complex environment,and the uncertainty of the marine refrigeration system’s own parameters and the complex coupling between the output parameters of the internal components and other practical problems,the stability control faces certain difficulties.The auto disturbance rejection control does not need to know the precise mathematical model of the controlled object,and can observe and estimate the uncertainty information and external disturbances inside the controlled system and compensate for it.The auto disturbance rejection decoupling control for the ship refrigeration system is proposed,and the ship refrigeration is combined.The characteristics of the system improve the active disturbance rejection control.The working principle and working characteristics of the marine refrigeration system are analyzed,and the influence of parameter changes on the ship’s refrigeration cycle and the coupling relationship between the internal parameters of the system are summarized;the main components of the marine refrigeration system are mathematically modeled and synthesized.The sixth-order dynamic nonlinear model of the whole marine refrigeration system is presented.The transfer function of the controlled system is determined by parameter identification,and the second-order model with time lag is identified for the representative compression refrigeration system in the marine refrigeration system.In view of the strong coupling characteristics of the marine refrigeration system,the static decoupling method is used to decouple,and the dynamic coupling part is used as the internal disturbance of the system,and the expanded state observer is used for real-time estimation and compensation;on the other hand,the BP neural network is used The ability to approximate nonlinear functions adds system information to the extended state observer,reducing the burden of observation and improving the accuracy of the observer’s estimation.In the simulation comparison experiment,by comparing the control capabilities of the classic PID control and the traditional ADRC controller,it is verified that the neural network ADRC decoupling control not only has advantages in the response speed of the system,the convenience of parameter adjustment,and anti-interference,And also has outstanding performance in robustness.Integrating the characteristics of the ship’s refrigeration system and the neural network active disturbance rejection control,the integral-order PD combination control has limited improvement in the control flexibility and response speed of the refrigeration system.In order to improve the control accuracy of the marine refrigeration system,an improved PD control combination is proposed.The first-order control combines the fractional-order auto-disturbance rejection controller with the active disturbance rejection control,which introduces the gain margin and phase margin to analyze the control stability,and combines with the BP neural network auto-disturbance rejection to establish a complete marine refrigeration system controller.Finally,the comparison of simulation experiments proves that the designed active disturbance rejection controller has strong suppression ability to the disturbance of the ship’s refrigeration system,fast response to the control of the system,strong robustness and excellent tracking performance,and achieves the stability of the marine refrigeration system.