A Method for Evaluating Energy Efficiency to Justify Power Factor Correction in Ship Power Systems

A poor power factor is often overlooked in ship power systems where electric motors are widely used to drive a variety of machinery and operate numerous processes. By reducing the reactive power produced by power generators through power factor correction (PFC), not only have system operating efficiency and economic targets been enhanced but greenhouse gas emissions have been also reduced. An evaluation of the economics of power factor improvement should take into account diesel electric generator loading, fuel oil consumption rate, running time, operating efficiency, and the production of emissions. This will help achieve energy-saving evaluation and ensure that the additional capital costs of installing a PFC system will provide an adequate rate of return on investment. This paper presents the methodology and results for the economic evaluation of PFC in marine vessels. A mathematical model, used to determine the relationships among fuel oil consumption, emission, and power factor for the diesel electric generator, is derived to quantify the possible benefits with PFC. An economic evaluation method using present worth analysis is performed to evaluate the PFC system. Numerical analysis and field test of practical ship power systems confirm the validity of the proposed approach and the critical parameters for PFC economics are determined.