Research On Multi-objective Optimal Operation And Economic Dispatching Of Marine DC Microgrid

With the rapid development of global trade,more and more marine ships have caused serious environmental pollution at the same time.In order to realize energy saving,emission reduction and sustainable development of energy,the shipping industry has put forward the concept of "new green ship".In order to connect marine new energy generation into marine power system on a large scale,it is of great practical significance to study ship DC microgrid.This thesis studies the optimal operation and economic dispatching of ship DC microgrid.The main research contents are as follows:1.The marine DC microgrid with redundant bus structure is constructed.Power generation units are formed with wind power generation,photovoltaic power generation,micro gas turbine power generation and fuel cell power generation.Energy storage units are formed with lead-acid batteries.Establish the corresponding mathematical model according to the working principle of each distributed power supply.The optimal operation and economic dispatching model of ship DC microgrid is constructed.The particle swarm optimization algorithm(PSO)is used to solve the economic optimal goal and the environmental optimal goal respectively,and the single-objective economic dispatching scheme is obtained.The analysis of the example shows that the two objectives conflict with each other and cannot be optimized at the same time.2.Aiming at the limitation of PSO in solving multi-objective problems,the following improvement measures are proposed: 1)In order to optimize the state of the initial particles,the particles are initialized using the minimum Euclidean distance;2)A strategy of selecting optimal zero based on single objective optimization is proposed to solve the problem of unreasonable selection of global optimal position.3)In order to solve the problem of improper maintenance of external files,the last particle elimination mechanism is introduced according to the congestion distance between particles.4)In order to solve the problem that the particles tend to be homogenized,the particles in the external files with low selected frequency are selected to update the global optimal position;5)In order to solve the problem that individual optimal location cannot be updated,an individual optimal location updating strategy based on timestamp is proposed.6)The adaptive inertia weight which decreases with the number of iterations is adopted to coordinate the convergence speed and accuracy of particles.Compare the standard multi-objective particle swarm optimization algorithm(MOPSO)and the improved MOPSO by ZDT1、ZDT2 and ZDT3 function.The simulation results show that the improved MOPSO is superior in convergence,diversity and convergence speed.3.In the process of ship DC microgrid operation,comprehensive consideration of economy and environmental protection is essential,which makes the optimal operation and economic dispatching of ship DC microgrid a complex problem of multi-objective,multi-constraint and non-linearity.The standard MOPSO and the improved MOPSO are used to solve the problem respectively.The simulation results show that the improved MOPSO has fewer iterations and the economic scheduling scheme is better.At the same time,an optimal operation strategy of storage battery is put forward to make the life of the battery longer,and the simulation results show that after considering battery optimal operation strategy,has been working in reasonable charged battery state,decrease the number one scheduling cycle charge-discharge,improved the running condition of storage battery.