Response of an AC - DC hybrid transmission system to faults in the AC network

Existing transmission corridors in power systems have to be efficiently utilized because new transmission systems are expensive and the realization is complex and time consuming. Upgrading existing AC transmission systems by adding DC circuits is a potential solution for increasing the transmission capacity of a corridor. It results in an AC and DC hybrid transmission system in which the converter stations at the ends must participate in the steady-state and dynamic control strategy of the interconnected power system. In this paper the control structure of the High Voltage Direct Current converter is introduced and the dynamic response of an AC and DC hybrid transmission system during AC grid faults in the interconnected power system is investigated.