Substations for Future HVdc Grids: Equipment and Configurations for Connection of HVdc Network Elements

With the increased integration of renewable energy generation, high-voltage direct current (HVdc) will become more prevalent in the power system. Anticipated annual growth rates are in the range of 7-10%. While most systems in operation and under construction are pointto-point connections, the first multiterminal HVdc systems have already been commissioned. As a next step, HVdc grids are being considered as a cost-effective solution to transmit power. These HVdc grids are expected to gradually develop from existing point-to-point links, mirroring the development of ac grids throughout the 20th century. Such HVdc grids will be an integral part of the power system, operating as a separate transmission layer of the future hybrid ac/dc network.