It was recognized in the report that due to planning constraints and environmental concerns, traditional methods of enhancing system capacity can be difficult to achieve and consideration was given to employing the latest technology, especially where this would yield additional economical and environment benefits. One such technology potentially contributing to the achievement of the above aims is HVDC transmission.
The Western High Voltage Direct Current (HVDC) link uses the thyristor based AC/DC converter technology and was proposed to be built as a major link across the Anglo-Scottish border to increase the inter-area power transfer capability and eliminate the constraints currently imposed on the border transfer for stability reason. In addition, there are many more HVDC projects that are currently under consideration and require a model which can be used in simulation studies effectively, accurately and easily.
National Grid has not previously implemented HVDC modelling in the old system analysis suites. The model provided by DIgSILENT in PowerFactory has been studied comprehensively and the results were reported in TR (E) 466; Computer simulation Tests of HVDC converter model in DIgSILENT. One of the major short comings identified in the model is the lack of the representation of the reactive power control while the converter operation moves from one level to another. It is essential and urgent to develop the reactive power control function and incorporate it into the current model for future use. The developed model will be crossed checked and verified by means of a real time digital simulator.