Harmonic filter design for Variable Frequency Drives in marine vessels based on a systematic power quality assessment and monitoring methodology

In the maritime industry, high fuel costs encourage the use of Variable Frequency Drives (VFDs) for energy saving applications. However, introduction of such nonlinear loads in the vessel's power distribution network induces harmonics, which can lead to potential risks if are not predicted and controlled. In this paper, several harmonic attenuation options are initially investigated for VFDs used in marine vessels. A systematic power quality analysis and monitoring methodology is then proposed to assess the size of required harmonic filters in order to satisfy voltage harmonic distortion limits imposed by marine classification societies when VFDs are applied to motors. The effectiveness of the proposed power quality analyzing procedure and monitoring methodology is evaluated through a real practical example, which includes harmonic filter design for VFDs applied to engine room fan and pump motors that operate constantly at sea-going mode in a typical tanker vessel. Experimental results obtained from power quality measurements verify that design complies with relevant marine harmonic standards even in the worst case of operation.