Substation layout for multi-terminal HVDC systems and neutral conductor arrangements for reduced field emissions

Beside the future need for offshore HVDC grids also the need for future onshore HVDC grids are currently extensively discussed. The requirements for HVDC substations as well as for HVDC connections for onshore and offshore applications differ a lot. This paper highlights the requirements for onshore HVDC substations and describes a solution for a multiterminal switchyard topology. This also includes a discussion on different busbar configurations and gives a proposal for the most suitable option with some switching examples in case of different line fault scenarios. Additionally some earthing options for substations of multi terminal systems are discussed. One important requirement for onshore HVDC substations is a small foot print and environmental compatibility. Thus also a new SF6 substitute is taken into considerations. Finally a proposal for new neutral conductor arrangements for overhead transmission is outlined which significantly reduces field emissions and thus is potentially increasing public acceptance.