Stability improvement of electric ship propulsion system using supercapacitor

Abstract

Owing to the serious greenhouse gas emissions and inflexible control of traditional ship propulsion system, the electric ship propulsion system has been widely introduced into the ship’s power system. However, the variations of ship propellers will lead to the instability of electric propulsion system so this paper studied the transient characteristics of electric ship propulsion system by performing a series of experiments on a real electric ship propulsion system platform. Based on the experimental results, a detailed model of supercapacitor energy storage system (SCESS) is proposed to improve the voltage and frequency response for the electric ship propulsion system. To enhance the stability and reliability, a double closed-loop control method combined with Pulse-Width Modulation algorithm (PWM) is utilized to control the energy storage system for smoothing the power fluctuations caused by the electric propulsion system. The simulation results demonstrate the high efficiency of supercapacitor to improve the transient stability of the whole power system of the ship.