Building a new overlay grid for Europe

The strong growth and the expected further increase in renewable energy generation in Europe requires a fundamental upgrade of the transmission system. A potential option is to realize these upgrades at a higher voltage by constructing a new overlay grid or supergrid. Such a supergrid is likely to be built using VSC HVDC technology, especially when considering that a significant part will be offshore. The paper will first discuss how such a grid should be conceived. Aspects that will be covered are the potential topology of such a grid and the balance between mesh size and the connection to the AC system. It will be discussed how such a new overlay grid with multiple controllers interacts with the existing system. The second aspect that will be covered is the stepwise development of such a system. A new overlay grid will not be conceived in a single phase, but link by link. The differences between “green field” and “brown field” approach are highlighted and shown using an example.