Grid Segmentation – Sequence

HVDC and HVAC

The joint application of HVAC and HVDC technologies has a long history in large grids. HVDC lines have been successfully used within large HVAC grids, though not without initial difficulties and reliability issues. HVDC has been particularly effective for asynchronously interconnecting HVAC grids where the application of synchronous ties was either impracticable or politically undesired.

At first look, DCI’s approach to integrating HVAC and HVDC transmission technologies may seem to lead to a configuration similar to asynchronously interconnected systems in North America and elsewhere (for example, the Hydro Quebec grid in relation to the rest of the Eastern Interconnect).

However, what DCI proposes is quite different from many perspectives, including motives, scope and the techniques to be used to achieve grid segmentation in a cost effective manner for all involved service areas. For instance, we envision the HVDC links between the ac sectors to consist mostly of HVAC ties converted to HVDC circuits to boost transfer capability while preventing inter-sector cascading.

The figure below shows back-to-back dc links in blue, existing ac lines converted to dc in red, concatenated and converted ac lines in orange, and future long haul dc lines in green.


 

 


Blue: back to back dc links inserted


Red: Existing ac lines converted to dc


Orange: concatenated and converted ac lines