From ‘joining the dots’ to ‘connecting the lines’
ABB breakthrough to enable DC grid vision
The evolving grid needs to be increasingly flexible and interconnected, as well as more reliable and intelligent to address new challenges like large scale integration of renewables.
The ability to transfer large quantities of electricity across vast distances with low losses and using minimal space combined with the feasibility of going underwater or underground make HVDC (high voltage direct current) a sought after technology across the world.
Deployment of HVDC has led to an increasing number of point to point connections in different parts of the world. The logical next step is to connect the lines and optimize the reliability of the network. This will also enable balancing of loads, integration of intermittent renewables, lowering of transmission losses and facilitate energy trading across borders.
Countries like Germany could well be the incubator for such a vision and has many of the elements that call for the development of a more interconnected grid. Several studies including the recent NEP plan and network study II by Dena (German Energy Agency) have examined the feasibility of using HVDC technology to connect renewable energy sources in the north with load centers in the south. Such a DC connection could later be integrated with an overlay grid to augment optimization efforts and conventional attempts to expand the AC grid. In fact, ABB engineers first conceived a vision for the European grid in the 1990s.
Then why don’t we just interconnect these lines into a grid ? A major stumbling block or missing link has been the absence of an HVDC breaker that acts fast enough to interrupt current and isolate faults and at the same time keeps losses to a minimum. ABB has now developed a solution to this century old challenge, which probably contributed to Edison losing out in the ‘battle of currents’. Of course, in addition to closing technology gaps, we also need political and social consensus, standards, funding models and a regulatory framework to be put in place.
ABB’s technology portfolio already enables the construction of multi-terminal systems that can be further developed into HVDC grids. Other key technology components are under development but the Hybrid HVDC breaker provides the vital missing link to revitalize visions such as the European grid or Desertec. It is also a clear signal that from a technology perspective, the planning for DC grids can proceed in full earnest and hopefully not before long we shall see some of the visions being turned into reality.