Minimizing THD in Railway’s HOG using MLI in Hybrid Distributed Generation System

This study describes a unique seven-level “reduced switch inverter” that have an LC filter aimed to minimize the amount of total harmonic distortion (THD). Traditional inverters often produce waveforms of output current and voltage significantly deviating from sinusoidal shapes mainly due to high THD percentages. Such waveforms are unsuitable for electric drives in coaches and renewable energy-based loads. To address this, a 7-level “reduced switch inverter” is proposed, where increasing levels in the output waveform bring it closer to a sinusoidal shape, limiting THD. This 7-level MLI is proposed consisting of five switches, Solar PV, a rectified power supply from HOG (Headon Generation), and two batteries using phase disposition PWM (PDPWM). It significantly reduces THD, resulting in a near-sine wave-modulated output. Furthermore, several filters are employed to lower the THD even further. MATLAB software is used for waveform analysis and system model simulation.