A hybrid HVDC transmission system supplying a passive load

The operational characteristics of a Voltage Source Converter (VSC)-HVDC transmission system make it a versatile asset in modern power systems. The advantages of the new technology are somewhat offset by some drawbacks, such as the high power losses, equipment insulation stresses, and relatively high cost. A hybrid Line Commutated Converter (LCC)-VSC HVDC transmission system combines the benefits of both conventional LCC and new VSC technologies. In this paper, a hybrid HVDC system is used to supply a passive AC network. The control systems for rectifier and inverter are discussed, along with additional control schemes for starting, load shedding, and potential AC network fault situations. The operational characteristics of the hybrid system under selected control modes are validated by EMTP-RV simulation under both steady state and transient conditions such as load shedding and AC faults. Finally, a brief performance analysis of transmission efficiency and harmonic distortion is presented.