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This paper discusses contemporary problems concerning ship microgrids. It focuses on the role of power electronics and power quality issues, both conventional, such as voltage and frequency variations, and new issues, such as waveform distortions ensuing from the wide proliferation of power electronics in ship microgrids. The paper also contains a discussion on the provisions of the Unified Requirements of International Association of Classification Societies and other leading power quality standards in the industry, with an emphasis on Total Harmonic Distortion (THD) definition. An overview of power converters for high power applications in ships and their impact on ship networks is also given. Next, original results of various power quality phenomena recorded in ship microgrids are presented and commented on, followed by a review and recommendations for maritime microgrid modeling and signal processing methods for power quality assessment in the discussed systems. Finally, preliminary proposals for power quality control are presented.

Abstract-Power quality (PQ) is becoming more and more critical issue in shipboard microgrid systems (SMG). Especially, the impact of voltage unbalance combined with harmonic distortions on the SMG behavior has not been fully investigated. In this paper, simple power quality assessment models and a series of controlled experiments are proposed and carried out in a real ship under seagoing conditions. The ship experimental results are presented and discussed considering non-linear bow thruster load and high power ballast pump loads under unbalanced and harmonic voltage conditions. In addition, the analysis of bow thruster current harmonic surges during the ballast pump start-up is presented. Furthermore, the voltage/current distortions of working generator, bow thruster and pump loads are analyzed. The paper provides a valuable analysis for coping with PQ issues in the SMG.

Abstract-Power quality (PQ) becomes more and more pressing issue on shipboard microgrid systems (SMG). Especially, the impact of voltage unbalance combined with harmonic distortions on the SMG behaviors has not been well investigated before. For this paper, a series of controlled experimental investigations were proposed and carried out in a real ship under sea-going conditions to address this problem. The ship experimental results were presented and discussed considering non-linear bow thruster load and high power ballast pump loads under unbalanced and harmonic voltage conditions. In addition, the analysis of voltage transient dips during ballast pump starting up is presented. Further, the voltage/current distortions of working generator, bow thruster and pump loads are analyzed. The paper provides a valuable analysis for coping with PQ issues in the real ship power system.