Modelling the impact of load changes on a notional all-electric ship power system

Abstract

Electric propulsion is becoming the standard for future ships. Electric propulsion brings several advantages such as increased fuel efficiency, reduced emissions and flexibility in power system design. All-electric ships are powered by generators that feed various shipboard loads. Load changes are reflected in the system voltage and frequency and must be controlled to maintain system stability. The aim of this project was to design a software model on PSCAD that represents an actual all-electric integrated ship power system, implement the frequency and voltage droop controllers, simulate the system to test its behaviour under realistic operating conditions, and recommend techniques to improve the overall system performance. Actual parameters from generator and machine manufacturers were utilised to model the system such that it reflects an actual ship power system. The results show that the power system does in fact react differently in different loading scenarios. By implementing frequency and voltage droop control, the generators shared the active and reactive load power depending on their respective droop settings. The power system did not become unstable in any scenario as it was able to reach steady-state operating conditions after applying several load changes. It is recommended that further research in this field will focus on the improvement of the overall system power quality due to the effects of non-linear loads such as VV/Vf (Variable Voltage/Variable Frequency) drives.