Abstract:
Objectives In order to suppress the occurrence of a massive bus voltage drop caused by a large-power pulsed load entering the Medium Voltage Direct Current (MVDC) power system of the ship and to maintain the bus voltage within the required safety margin, the Hybrid Energy Storage System (HESS) is a promising solution to this problem. However, the hybrid energy management strategy of the ship MVDC system can greatly affect the energy efficiency of the system.
Methods Therefore, the PI controller and fuzzy logic controller are designed to predict the reference power of HESS to meet the load power demand. The two methods are analyzed and compared. In light of the energy imbalance existing between the lithium battery and super capacitor, we then design the second-level fuzzy logic controller for redistribution of power. The Matlab/Simulink models of MVDC system, HESS, constant power load and pulse load were established for simulation analysis.
Results The simulation results show that the fuzzy logic controller and PI controller can predict the required power of the system according to the state of the MVDC system, and the fuzzy logic control strategy is superior to PI control strategy. The second-level fuzzy logic controller can redistribute the power reasonably based on the state of charge between the lithium battery pack and the supercapacitor bank.
Conclusions The hybrid energy management strategy of the ship's MVDC system can maintain system power balance, suppress busbar fluctuations, improve system stability and survivability.
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