Long-term experience of DC-microgrid operation

In order to make DC-microgrids a reliable backbone of industrial or commercial buildings, the reliability of the technology must meet highest standards and even surpass that of AC-grids, which they aim to replace to eliminate blackouts of the AC-grid. Therefore, we operated a DC-microgrid under laboratory conditions, i.e. including modifications and upgrade, while aiming at long-term operation. In this presentation, we list the most common issues which occurred throughout the last 6 years, evaluate the meantime between failures, and analyze the failures according to sub-groups like software, power-electronics, other hardware, and regulation issues. As common in quality assurance once the failure distribution is known, the most frequent issues and/or those having the most severe consequences will be eliminated first. Proper dimensioning of power converters on the one hand and an energy management system on the other hand, taking the time scales of reaction of the communication and the specifications into account, are crucial. In addition, a concept for functioning even after loss of communication between the “smart” components is another key element for stable operation.