Research On Energy Storage Control Technology In Marine Electric Propulsion System

In the marine electric propulsion system,the AC-DC-AC voltage source converter is operated more frequently.However,because the power of the propulsion motor is relatively large,the DC bus side voltage will drop when the ship is started.In the case of ship braking,the feedback energy generated by the brake also returns to the DC bus side,thereby increasing the bus voltage.In this paper,an energy storage scheme using supercapacitor is designed.Supercapacitor can compensate and absorb the bus side energy,so that the bus voltage can fluctuate within a controllable range and improve the stability of electric propulsion system.Firstly,this paper compares and analyzes the current energy storage schemes of ship electric propulsion system,and designs an energy storage system based on super capacitor.The uneven distribution of electric energy in the practical series application of super capacitors is studied,and a six switches super capacitor voltage sharing circuit is designed.The six switches control the voltage sharing of three groups of super capacitors.Improve voltage equalization capabilities,suitable for a large number of supercapacitances.Secondly,various working conditions of ship electric propulsion system are analyzed.The connection device between the super capacitor and the DC bus uses a Buck-Boost converter to realize the two-sided energy flow.The entire architecture of the electric ship propulsion is equipped with a super capacitor bank,and a sensible control strategy is formulated to actively enable the super capacitor bank to suppress the bus voltage.Under normal operation,it can meet the requirements of various working conditions of electric propulsion system.Finally,the energy storage capacity of the super capacitor bank in this design is obtained through capacity calculation.The overall simulation model of the electric propulsion system is built in MATLAB/Simulink to simulate and analyze the conditions of ship startup,acceleration,deceleration and sudden power outage on the net side,which confirms the effectiveness of the energy storage system and the control strategy,At the same time,the effectiveness and rapidity of the six switches voltage equalizing circuit are proved.