Pourhossein, Kazem

The dtec.bw project CoupleIT! – IT-based sector coupling: Digitally controlled fuel cell and electrolyzer technologies for stationary and mobile applications is an interdisciplinary approach to combine a wide range of competencies from disciplines as varied as electrical power systems, economic and social sciences, computer sciences and networks as well as sustainable development and social acceptance research. As such, this article is composed of individual contributions, constituting the main chapters that showcase general approaches and motivations but also concrete results. This compendium article starts in with a delineation of the motivation behind research in so-called microgrids composed of fuel cell and electrolyzer components and a presentation of the microgrid architecture opted for in this project. Chapter two goes into more detail on the side of electrical engineering and the feasibility of a parallel operation of inverters in microgrids to achieve the ability for an upscaling. Chapter three highlights economic and technological factors for an economically viable and grid-maintaining deployment of a hydrogen-based energy system. In addition, degradation of Li-ion batteries is discussed against the background of their flexible operation in a microgrid and other scenarios. Chapter four grants a glimpse into the field of computer science and the possibility to use artificial intelligence and neural networks for a new way to simulate the behaviour of matter on atomic and molecular scales. This approach holds potential to increase the efficiency of fuel cells by improving the molecular design of fuel cell membranes used within this project. Chapter five elucidates the intricacies of secure communication within one but also between multiple microgrids, an important aspect for achieving a resilient system. Chapter six concludes this compendium by highlighting the human perspective seen from the field of psychological acceptance research nested in the broader context of sustainable development. Among other things, areas of potential barriers to a public acceptance of hydrogen technology are identified and ways to overcome those barriers proposed. This interdisciplinary round trip starts with electrical engineering (chapters one and two), economic and social sciences (chapter three), followed by computer sciences (chapter four) and computer networks (chapter five) whence the baton is passed for one last time to the field of sustainable development and psychological acceptance research (chapter six).

Utilizing multi-energy renewable microgrids is a promising prospect for decentralized electric power generation. To form a multi-energy microgrid and integrate different renewable energy sources, grid-forming inverters are the core elements. Therefore, their performance has to be tested and validated to increase the quality and reliability of the power supply. The present paper investigates the suitability of a specifically designed and implemented grid-forming inverter as the central component in such microgrid systems. Quality of black-start, frequency and voltage regulation, fast transient response, energy efficiency, low harmonic distortion, proper power factor control, synchronization and phase alignment for integration of renewable energy sources and energy storage devices such as photovoltaics and lithium-ion battery bank, respectively, fault-ride through capability, and resilience to fluctuations imposed by loads are the main features that have been tested and validated for a laboratory-scale grid-forming inverter. The study focuses on the parameters essential for ensuring the reliable and efficient operation of the inverter in dynamic and diverse energy environments, especially its adaptability to varying load profiles and its resilience towards intermittent energy inputs. The findings from this performance evaluation contribute insights for engineers, researchers, and industry professionals involved in the design, deployment, and optimization of multi-energy microgrids.

Grid-forming inverters are the essential components in the effort to integrate renewable energy resources into stand-alone power systems and microgrids. Performance of these inverters directly depends on their control parameters embodied in the controller. Even the most conscientiously designed controller will exhibit suboptimal performance upon implementation due to the presence of parasitic elements in the existing hardware. Hence, the controller has to be tuned and optimized. In the present article, the process of implementation, laboratory verification, and tuning of a matching-controlled grid-forming inverter is presented. In order to assess the efficiency of the grid-forming controller, its operation has been tested and analyzed in blackstart, steady state, and transient operation. For this purpose, a systematic sensitivity analysis has been conducted and the control parameters have been tuned in laboratory tests. The laboratory results verify proper operation of a 7 kW grid-forming inverter in all three test scenarios. After applying the proposed method on the tested grid-forming inverter in steady state operation, total harmonic distortion (THD) of the output voltage is less than 0.5% for its practical loading range (maximum THD is less than 1% in no-load condition). The system is able to blackstart and supply the loads. Finally, the studied grid-forming inverter is stable in the presence of severe step load changes and disturbances, i.e., voltage overshoot is managed well and compensated for with a low settling time using this approach.