Pulsating DC Power Minimization in a Multi-port DC/AC Converter by an Adaptive Phase-Shift in the Single-Phase AC Ports

This paper presents a method to minimize the DC bus power low-frequency oscillations in a building micro-grid composed of renewable resources, batteries, and single-phase AC loads. Most of the time, DC-AC inverters provide energy to AC loads with random power factor and voltage phase reference. Usually, a connection of several single-phase inverters in parallel to the same DC bus increases low-frequency power oscillations at twice the frequency of AC side, leading to a reduction in Li-ion batteries and capacitors lifetime connected to the micro-grid. To solve the problem, a method is proposed to mitigate DC bus power low-frequency oscillations. The inverters are implemented in hardware in the loop (HIL), considering a centralized lead DSP and node inverters DSPs. Each node receives a reference and is responsible for load current and voltage control. The tested system presented more than 90% of DC bus power oscillation reduction.