A modified Five-Level NPC Transformer-less Bi-directional Solar Home Converter for Grid Services

The increasing demand for renewable energy has driven significant advancements in power conversion technologies, particularly single-phase inverters, vital for solar integrated dwellings. Despite the benefits of single-phase inverters, including transformer-less designs and multilevel topologies, several challenges remain, such as managing high ground currents, providing frequency and reactive power support to the grid and ensuring low-cost, high-efficiency solutions. This paper explores the evolving landscape of inverter technology, highlighting innovations in transformer-less and modified multilevel converter operations. A strong emphasis is placed on the necessity for advanced bi-directional inverters that can offer grid services. The paper presents a novel operating principle for a T-Type 5-level neutral point-clamped inverter that functions in both inverter and rectifier modes. This design adheres to grid codes EN 50438 and EN 50549 using traditional dq control methods. The MATLAB-based simulation platform is used to demonstrate the efficacy of the proposed system.