Abstract:
This thesis concentrates on the stability performance of HVDC-HVAC interaction of the
transnational HVDC interconnection between Sri Lanka and India. This transmission line
under consideration since mid-1970 and the prefeasibility study was done by India in
cooperated with Sri Lanka together. In this study it was focused on modeling the HVDC link
between Indian and Sri Lankan power grids with the basic control system and studying the
transient stability performance of the HVDC interconnection under the Sri Lankan
transmission network perturbed conditions. The complete system was modeled on
PSCAD/EMTDC software. The complete system was divided into five subsystems while
modeling as, rectifier side AC source, converter transformers and converters, DC
transmission line, HVDC control system and inverter side detailed Sri Lankan network. The
simulations were done for steady state conditions, for system accuracy verification and for
different system perturbed conditions. The analysis was done based upon the maximum
power curve, Short circuit ratio (SCR) and time domain analysis. It was found that; modeled
Sri Lankan network is a strong network for the proposed HVDC interconnection in steady
state condition. However, there is a considerable impact on the stability of HVDC-HVAC
interaction under different perturbed scenarios of Sri Lankan AC network. This study
discusses the results obtained from the qualitative and quantitative analysis.
was
The results obtained from this study can be taken as guidance during the planning
and designing stage of the proposed DC interconnection to have an idea on stability
of the AC-DC interaction. The DC power operating curve, maximum DC power infeed to inverter side Sri Lankan network, AC system strength behavior during
different disturbances, time domain faults behavior, impact ofAC system impedance
on the stability are the facts which are discussing in this thesis. Therefore, this thesis
can be consider as guidance for the planning stage ofthe proposed interconnection.
