Ancillary services in electric power systems with HVDC grids

An electrical power system is intended to transmit power from generation to load. To do so, it needs ancillary services to guarantee a certain level of reliability and quality. With the emergence of DC grids, it becomes necessary to ask what ancillary services they may themselves require, and how DC grids should be required to interact with the remainder of the system. This study defines a first basic set of ancillary services for High Voltage Direct Current (HVDC) grids which did not exist so far, and it shows that this development could affect the ancillary services in AC grids. This study describes how the origin of ancillary services can change if an HVDC grid is added to the existing AC grids and gives an overview of existing definitions for ancillary services.