Medium Voltage DC Systems in Electricity Distribution Networks

EPSRC Portfolio Areas: Energy storage, Solar technology

Description:
Solar PV and energy storage systems have been widely recognised as one of most effective ways to address energy and environmental issues. Several power electronic converters are required to manage the power flow from solar PV panels to energy storage and power grid. As a result, such converters can determine the overall performance, e.g., efficiency and power density, of the solar energy storage system.

Numerous control methods, topologies, and modulation strategies have been recently proposed to improve power density, efficiency, reliability, and costs of the converters. However, two major challenges remain as critical obstacles to further advance these. The first challenge is the bulky electrolytic capacitors used to reduce voltage ripples, which are the most vulnerable components in the converters. They can cause about 30% of failures, and occupy 83% of the volume in a small power converter. The second challenge is the inefficient and bulky isolation transformers used to isolate leakage currents. Such transformers can account for about 3% of system power losses, over 60% of weight, and over 50% of volume in a 6 kW PV inverter.

In this project, we aim to develop a 5 kW highly efficient, reliable and small-sized converter system for solar PV energy storage systems through 1) advanced design of power topologies to remove isolation transformers and electrolytic capacitors; 2) design of high-frequency inductors to reduce system size and weight; 3) control system design to improve system dynamics; 4) simulation and experimental verification of the developed power converters. With the commitment from Solar Ready Solutions, routes to commercialization of the developed converters will be included as a part of this project.