Control of capacitor commutated converters in long cable HVDC-transmission

HVDC transmission over long distances is becoming more common, partly due to the deregulated environment in the electricity industry. The capacitor commutated converter (CCC) is a new type of HVDC converter topology which shows promise for use in long distance transmission via cables. This technology is, thus, a potential candidate for use in HVDC transmission across large bodies of water. Several HVDC-connections with cable lengths of about 600 km are currently in the planning stage in Northern Europe. This paper proposes two possible control options for such extremely long cable HVDC-connections. The suitability of these control alternatives in a CCC-inverter based HVDC-scheme terminating in a weak AC-network, is investigated using electromagnetic transient simulation.