Coordinated operation of HVDC and FACTS

Over the course of three decades of commercial applications, the HVDC technique has been established as a conventional technology in the area of back-to-back and two-terminal long-distance and submarine cable systems up to 2000 MW and higher. As thyristor-controlled shunt compensation schemes have been introduced into high-voltage transmission for more than two decades, FACTS (flexible AC transmission systems) devices are established as technical and economic means for improving the overall system performance of AC systems. Today, only limited HVDC and FACTS systems are operated in a coordinated manner. However, with increasing complexity of system conditions, e.g. in very weak power systems with enhanced stability requirements, parallel operation of HVDC and FACTS devices is gaining impetus. Innovative technologies can further optimize the HVDC performance under weak and very weak system conditions.