Final Report Summary - MODELING DC (Modelling platforms for high-power resonant DC hub and power networks with multiple converter systems)
The ERC project Modelling DC has achieved major results in terms of development of new components for DC transmission grids, their modeling methods, protection and control for DC grids. Two new components have been developed, namely: DC/DC converter and Multiport DC hub, and patent applications have been filed. These components can achieve multiple functions, like DC voltage stepping, power flow regulation and DC fault isolation, and they are expected to play major role in building future (offshore) DC transmission grids. Since DC transmission grids do not exist yet, and their technical principles will be different from the existing AC power transmission systems, this ERC project makes contribution in demonstrating feasibility of DC systems, enhancing understanding of their performance, design and operating principles, and in exploring performance-cost balance. The EU energy policy states that DC systems will play major role in integrating large-scale renewables and in strengthening EU power transmission system. Some significant advances have been made in modeling the latest Voltage Source Converters based on MMC (modular multilevel converter) technology which will likely constitute underlying technology for all power electronics components in DC grids. Modelling of MMC is challenging because of large number of individual modules, and in particular (offshore) DC grids will have numerous MMC converters which further complicates studies. The project has delivered a library of analytical models (in DQ rotating frame) for most of the converter technologies that are in use with HVDC (High Voltage Direct Current) and which will be employed in building DC transmission networks. The control system for DC transmission grid will be different from AC systems, and some promising methods have been proposed and evaluated in the project. The results from the project have contributed to various CIGRE professional working groups on DC grids. One book has been published, largely based on outputs from this project, and additionally over 20 articles have been published. Two patents have been filed and commercialization options are being exploited.