Research On Speed Control Strategy Of Marine Medium Speed Engine Based On Genetic Algorithm

Diesel engine still occupies a large proportion in the field of Marine power,but the strong nonlinear and bad working environment lead to the instability of Marine diesel engine speed.The instability of speed will seriously affect the working safety of diesel engine,and even endanger the personal safety of ship and crew.However,due to the limitations of traditional PID control,the current Marine diesel engine does not have the ability of self-recovery when the speed is unstable,and the phenomenon of speed instability oscillation often occurs.Therefore,it is of great significance to explore advanced Marine diesel engine control strategies,especially in the case of speed instability,to provide a new method of self-healing without relying on external forces for the control system.This paper takes marine medium speed diesel engine as the research object,aiming at the problems of speed instability and speed overshoot caused by sudden loading and unloading of load,and on the basis of traditional PID controller,a control strategy based on genetic algorithm is proposed to realize the online optimization of PID controller parameters,so as to meet the stable control requirements of diesel engine under complex and variable working conditions.In the process of designing the control strategy,this paper adopts the model-based simulation optimization method.Firstly,GT-Power software is applied to establish the numerical simulation model of the medium-speed engine,and the accuracy of the model is verified by comparing with the test data.Then,the speed control strategy of Marine diesel engine is designed based on genetic algorithm.Through the co-simulation of GT-Power and Simulink,the three parameters of PID controllerK_p,K_i andK_d are taken as chromosomes for binary coding.ITAE is used as fitness function when the engine is in steady state.When the engine is dynamic,the recovery time and overshoot are used as fitness functions,and the optimal control parameters such asK_p,K_i andK_d can be obtained by cyclic iteration such as selection,crossover and mutation.Finally,the feasibility of the control strategy in embedded control system is further verified by the hardware-in-the-loop semi-physical simulation experiment.The simulation results show that the speed control strategy of Marine medium-speed engine based on genetic algorithm designed in this paper can carry out stable control of medium-speed engine in the full range of working conditions.Compared with the traditional PID controller,the PID controller based on genetic algorithm has better adaptability and robustness.In steady-state engine conditions and transient engine conditions such as sudden loading and unloading,the genetic algorithm has better control parameter optimization ability,which verifies the superiority of genetic algorithm in speed control adaptive.