Exploiting voltage support of voltage-source HVDC

The inherent voltage support in voltage-source converters (VSCs) which form a back-to-back VSC–HVDC asynchronous link can increase the power transmissibility by a factor of 1.68 if the installation is sited at the midpoint of the radial AC transmission line. The figure of 1.68 is the limit set by the ‘transient stability’ which is reached by simulations using HYPERSIM, a real-time digital simulator. The transmission line is modelled by the telegraph equations. The hydraulic turbine, speed governor, generator, field-excitation system, power-system stabiliser (PSS) and transformers are modelled in detail.