Towards a (more) electronic transmission and distribution (eT&D)

The challenges and the path towards a (more) electronic transmission and distribution (eT&D) is presented in this paper. The challenges are first identified together with key stakeholders in the drive for grid modernization. A fundamental question is then asked about the investment priority. Six basic characteristics are reviewed, leading to the composition of structured microgrids as the basic functional cell of a modern grid. One example of fractal radial structure and one fractal meshed structure are presented. The likely evolution path is then proposed together with basic technology sets. Specific foundation technologies are discussed in detail, including adiabatic power conversion, 3MC technology, medium voltage conversion, distribution-level electronic power transformer and FACTs hardware integration, and back-to-back converters as a universal interconnect element. The rapidly emerging on-wire sensing technology is also discussed. It is pointed out that the distribution-level large electronic power transformer will provide a key component to enable hybrid ac/dc grid flow control and ancillary support for a flexible electronic transmission and distribution (eT&D) systems.