Analysis of the impact of AFE Active Front End on the THD on a shipboard power system: a comparison study using different simulation approaches

This paper proposes a method to calculate the THD% value of the line-to-line voltage waveform at the PCC (Point of Common Coupling) in a shipboard system using an interconnection between Simulink and a power simulator, ETAP. Nowadays, electrical shipboard systems are more and more characterized by AFE (Active Front End) drives that allow more flexibility in the power drive but they can affect the power quality. In this work, a simplified electrical shipboard scheme is modeled in Simulink environment in which harmonics, created by non-linear loads, are recorded through the “FFT Analysis Tool”. The converters are modeled in Simulink and they are controlled using a control scheme based on the “d-q theory”. An analogue scheme is built in ETAP that can perform an harmonic load flow; in order to execute this analysis, Simulink provides a mask that contains harmonics of the current waveform for each non-linear load and these data can be used as input in ETAP. A comparison and a sensitivity analysis has been carried out using the THD% values and the harmonic spectrums collected in ETAP and Simulink in different power conditions to verify the proposed study.