Design of passive harmonic filters to enhance power quality and energy efficiency in ship power systems

Variable frequency drives (VFDs) driven motors for pumps, blowers and fans, and heating, ventilation and air conditioning (HVAC) equipment on ships are rapidly growing in number. Due to their nonlinear nature, they become the major sources of harmonics in electrical power systems on board. To mitigate the harmonics, passive harmonic filters that are an LC circuit tuned to each harmonic order to be filtered have been used. In compliance with the new rule in the emission regulation of the maritime industry, the installation of passive filters has attracting more attention in managing service power energy efficiency. This paper proposed a design of passive filters to reduce the voltage and current distortions in ship power systems while increasing energy efficiency with power factor corrected by passive filters. The inductance and capacitance in the filter are designed according to harmonic currents and reactive power required. The on-board power system of a practical ship with a great number of VFDs is analyzed to illustrate the filter design. The field testing results verified the performance of system with the filter designed by the proposed method.