Research On Risk Assessment Technology Of Ship Integrated Electric Propulsion System

With the rapid development of science and technology,integrated electric propulsion ships is gradually replacing traditional propulsion ships and becoming the development trend of modern ship.And the risk integrated electric propulsion ship has become a significant evaluation index,which is a necessary condition to keep the system operation efficient,safe and reliable,so the risk assessment technology of ship integrated electric propulsion system has become an important problem which is urgently needed to study and solve.In this paper,the risk assessment of ship integrated electric propulsion system is studied,a risk assessment mathematics modeling method of the unit of ship integrated electric propulsion system is proposed,as the foundation of the whole system risk assessment,After that,the model optimization and model validation methods of the ship integrated electric propulsion system network topology model is put forward,and the data of the optimized system model is used in risk assessment;This article firstly puts forward the steady-state risk assessment and risk prediction evaluation technology of ship integrated electric propulsion system,which combine the network topology model,optimal power flow analysis,Monte Carlo simulation the hidden Markov model and other intelligent algorithms and methods,and form integrated intelligent risk assessment system.Finally,the risk assessment of ship integrated electric propulsion system is completed.Firstly,this paper briefly expounds the development and requirements of ship integrated electric propulsion system risk assessment,the concept of ship integrated electric propulsion system risk assessment is put forward for the first time,and the problems existing in the current risk assessment are analyzed,then the whole framework and research content of the paper are introduced.Secondly,the component risk assessment mathematical modeling research is the basis of studying the risk assessment of ship integrated electric propulsion system,the structure characteristics of ship integrated electric propulsion system are analyzed,and the component risk assessment model of ship integrated electric propulsion system is given in detail,and component risk parameters calculation formula is given too.Then,the risk assessment method of unit group of ship integrated electric propulsion system is studied,after that,the risk assessment model and risk parameter calculation method of unit group of ship integrated electric propulsion system are given to calculate unit group risk parameters of ship integrated electric propulsion system as precisely as possible and lay the foundation for the whole system risk assessment.Thirdly,considering the physical connection and electrical connection attribute between the unit,the basic network topology model of ship integrated electric propulsion system is established,RS method is proposed to optimize the structure of the basic network topology model;MELM method is put forward to verify the optimized model,finally,the optimized network topology model parameters are calculated,and the branch data,node data and generation node data of the optimized model are given,and used in the risk assessment of ship integrated electric propulsion system.Then,combining network topology analysis,risk assessment,power flow analysis and Monte Carlo simulation,the steady-state risk assessment method of ship integrated electric propulsion system is put forward.According to the optimized network topology model parameters and component risk assessment model,node risk assessment matrix,branch risk assessment matrix and the generation node risk assessment matrix are calculated.Considering the uncertain and no NUinear characteristics of ship integrated electric propulsion system risk,the system risk is simulated by using nonsequential Monte Carlo,the load reduction caused by risk is analyzed by using risk assessment power flow analysis method,the risk assessment power flow analysis result is obtained through a large number of simulation tests,and compared with the power flow analysis result under normal working state,finally,the steady-state risk assessment results of ship integrated electric propulsion system are obtained.After that,this paper expounds the risk prediction assessment method of ship integrated electric propulsion system,combining Viterbi algorithm and the hidden Markov model,a unit group MHMM risk prediction method is put forward.According to the component state transition probability matrix and sea state transition probability matrix,the HMM modeling of all unit in the system are completed,then the unit group MHMM risk prediction method is used to generate the risk prediction sequences of all unit within time T,and the steady-state risk assessment method is used at each time point to get the risk prediction result in each time point,finally the risk prediction assessment results of the ship integrated electric propulsion system are got in time T.Finally,the steady-state risk assessment method and the risk prediction assessment method of ship integrated electric propulsion system are tested and verified.The steady-state risk assessment test includes two operation conditions,respectively full-load full-speed condition and half-load cruise condition.After testing 100 times,in the condition of full load sailing at full speed,the probability of load curtailments of ship integrated electric propulsion system is between 2.9% and 3.75%,the average probability of load curtailments is 3.3285%,the expected demand not supplied per hour is between 0.92 MW and 1.19 MW,the average value is 1.0143MW;in the half-load cruise condition,the probability of load curtailments of ship integrated electric propulsion system is between 1.39% and 1.98%,the average probability of load curtailments is 1.685%,the expected demand not supplied per hour is between 0.39 MW and 0.39 MW,the average value is 0.4861 MW.The steady-state risk assessment results under the two conditions are compared and analyzed,the conclusion is as follow: the risk of ship integrated electric propulsion system under full-load full-speed condition is higher,which is about double of that under half-load cruise condition,and the fluctuation of system risk parameters under full-load full-speed condition is bigger,and the high peak value caused by the fluctuation is more likely to lead to unexpected risk and load reduction.In the risk prediction assessment test,assuming that the risk prediction assessment time is 100 hours,the test also includes full-load full-speed condition and half-load cruise condition,in the condition of full load sailing at full speed,the probability of load curtailments of ship integrated electric propulsion system is between 2.59% and 4.76% with the changes of sea state,the expected demand not supplied per hour is between 0.81 MW and 1.53 MW,which fluctuates according to the changes of sea state;in the half-load cruise condition Half load cruising state,the probability of load curtailments of ship integrated electric propulsion system is between 1.34% and 2.56% with changes of sea state,the expected demand not supplied per hour is between 0.39 MW and 0.73 MW,which fluctuates according to the changes of sea state.The risk prediction assessment results under the two conditions are compared and analyzed,the conclusion is as follow: the risk of ship integrated electric propulsion system under two conditions fluctuate constantly with changes of sea state,and the risk of ship integrated electric propulsion system is higher and easier to cause load reduction in the high sea condition.