Outage of a large capacity link between two distant nodes in a synchronously interconnected system may result into excessive loading on parallel AC lines, severe drop in voltage profile, power oscillations and finally leading to a major blackout or brown out in the system, in case instantaneous corrective actions are not in place. On the other hand similar outage in an asynchronously connected system may result into load – generation imbalance on either side of the link.

Existing SPS in northern region
HVDC Rihand Dadri bipolar and 400 kV Muzaffarpur- Gorakhpur DC

To take care of contingencies of above nature the SPS for HVDC Rihand- Dadri bipole was approved in the northern region in June 2005.Subsequently, the northern regional grid was synchronized with the central grid through 400 kV Muzaffarpur- Gorakhpur D/C and the Rihand-Dadri SPS scheme was extended with same identified loads for shedding under the contingency of 400 kV Muzaffarpur- Gorakhpur outage also.