Research On The Intelligent Control Based Energy Management Strategy For Hybrid Ships

With the environment and energy issue drawing more and more attention,the clean energy hybrid power ships have been employed as an important approach to achieve energy saving and emission reducing in ship industry.The hydrogen fuel cell hybrid power system is featured by high efficiency and no pollution among many choices and is expected further prospect.Compared with single energy based power system,the hybrid power system is more complex.Therefore,it has been one of the key technologies to coordinate different characteristics between the power sources and energy storage system to make ships operate effectively and safely.Aiming at a battery powered prototype ship,the fuel cell、 battery and ultracapacitor hybrid power system is designed The wavelet transform and fuzzy logic based intelligent energy management strategy is adopted here to optimize the power output of each power source.The wavelet is used to split the power demand to each power source respecting their different characteristics while the fuzzy control can satisfy the power requirement of the ship.Such a strategy can extend the lifetime of fuel cell and battery as well as satisfy the efficiency and safety requirement.This thesis mainly includes the following aspects:Firstly,the hydrogen fuel cell hybrid system is designed.Aiming at the given passenger ship in inland water,the fuel cell/battery/ultra-capacitor hybrid power system is designed based on their characteristics analysis.Choose the proper topology structure after comparing the existing structures.Discuss the factors influencing the safety of the fuel cell systems and batteries and then design the system in the view of safety.Design the propulsion system as well as the data acquisition and control system and the interface of the energy management system.Furthermore,model the system in MATLAN/Simulink platform.The system is modeled based on the researches on the existing modeling method of each power source as well as the analysis on the principle and control method of the DC/DC convertor.The intelligent control based energy management strategy for the hybrid ships is designed.The wavelet is adopted to decompose the power signal,the approximation and detail coefficient are reconstructed respectively.Then the power signals of different frequencies are split to the power plants according to their dynamic performance.The inputs of the fuzzy controller and their membership functions are determined.The fuzzy rules are created according to the expert knowledge and the fuzzy controller is completed.Then the management strategy is modeled in the MATLAB/Simulink platform.Finally,the power requirement of the system is designed according to the power data of a fuel cell passenger ship.The system simulation is carried out aiming at two different conditions of the initial state of charge of battery and ultra-capacitor.The result shows that the proposed energy management strategy is capable of splitting the power requirement properly under the condition of different initial state of charges of the energy storage and keeping their state of charges within normal level.