Research On Energy Management Strategy Of Ship Micro-grid Based On Hierarchical Control

Micro-grid provides a new solution for ship energy consumption,environmental pollution and economic operation problems.At sea,marine micro-grid can be thought of as island micro-grid,where renewable energy generation technologies are gaining popularity as the need for emissions reductions and fuel efficiency grows.In this context,the integration of multi-energy and storage systems in ship micro-grid requires an efficient energy management system.These challenging environments and trends require customized advanced control and energy management solutions for marine micro-grid.In this paper,some problems in the ship micro-grid energy management system based on hierarchical control are studied:Firstly,the overall scheme of the ship micro-grid layered control system is designed,and according to the typical system structure of the ship micro-grid,the basic principles and characteristics of the internal distributed power supply are studied,and its mathematical model is established,which provides the basis for the construction of the ship micro-grid simulation model.Technical support to meet the basic theoretical requirements for the design of control strategies at all levels of the energy management system based on hierarchical control.Secondly,according to the functional requirements of primary control in hierarchical control,in view of the problems existing in the disturbance observation algorithm in the maximum power point tracking control strategy for renewable energy generation,an improved disturbance observation algorithm is proposed,which can adaptively adjust the disturbance step size,and designed the oscillation detection mechanism and voltage boundary strategy.The results of the example simulation show that the power loss of the algorithm is reduced by 69.3%compared with the traditional algorithm;the overall tracking time is prolonged by 15.4%,solved the steady-state oscillation phase and the problem of deviation from the tracking direction,the effectiveness and superiority of the proposed algorithm are verified.Thirdly,according to the functional requirements of secondary control in hierarchical control,in view of the voltage and frequency deviation problems caused by the first control of the micro-grid and load switching,in order to ensure the power quality of load power,a secondary coordinated control strategy of micro-grid based on dynamic droop coefficient is designed,and the droop coefficient of this strategy can be adaptively changed.The simulation results show that the control strategy can suppress the voltage and frequency fluctuations,the fast response and high sensitivity demonstrate the effectiveness of the control strategy.Finally,according to the functional requirements of tertiary control in hierarchical control,aiming at the complex day-ahead scheduling problem of ship micro-grid,the objective function is established with the operating cost of distributed power and the pollutants of diesel generators as indicators.Taking the system balance and distributed power output power limit as constraints,an improved particle swarm optimization algorithm was proposed,and the performance of the algorithm was compared with other three intelligent optimization algorithms.The test results show that the accuracy and search speed of the proposed algorithm are greatly improved.It is applied to the optimization dispatch objective function of ship micro-grid day-ahead to solve,the simulation results show that,the total cost of the distributed power output scheme given by this algorithm is reduced by 8.2%,and the environmental cost of diesel generators is reduced by 8.4%.It is proved that the control strategy is more economical and environmentally friendly.