Management of hybrid energy storage systems for MVDC power system of all electric ship

Abstract

In order to maintain the bus voltage of a medium voltage DC (MVDC) shipboard power system within the allowable margin with the operation of different types of loads, the energy storage has become an indispensable part of all electric ship (AES). In this paper, a PI controller based energy storage management (ESM) system is designed to control the charging and discharging of the hybrid energy storage systems (HESS) for supporting the MVDC system with the operation of the electric weapons. The HESS consists of a high energy density storage (battery) and a high power density storage (supercapacitor). Dual active bridge (DAB) converters with bi-directional capability are used to interface the HESS with the MVDC system. The ESM system generates instantaneous storage reference power with the change of the bus voltage and load power demand. A low pass filter is used to separate the total storage reference power between the battery and the supercapacitor. The reference powers of the battery and the supercapacitor are sent to the controllers of the DAB converters to control the power exchange between the HESS with the MVDC system. The MVDC shipboard power system with different loads, DAB converter with battery and superconductor are modeled in Matlab/Simulink environment. Simulation results are shown to show the performances of the PI controller based ESM system in different scenarios.