Identification & Reduction Of Circulating Mvar Loops At High Voltage Substations

Upgradation of substation voltage from 220 KV to 400 KV introduces looping configuration between transmission lines. Mismanaged tap position at power transformer side results in circulating Mega Volt Ampere Reactive power thus hampering system natural flows. Pertaining to such problem 400 KV Grid sub-station Ratangarh and Sikar situated in Rajasthan, India is taken for study. Prolonged uniform tapping of 400 KV transformers at 400 KV GSS Ratangarh, even after the commissioning of new substation lines, shunt reactors, generators in the network has simultaneously resulted in circulating MVAR flow between Sikar and Ratangarh transmission lines. Case study of 938 bus network Rajasthan system is carried. Effect of modified transformer tap position at 400 KV GSS Ratangarh from present tap position of 14 to 9 over PEAK/OFF PEAK system loadings and variable generation by Suratgarh Thermal Power Station with a load variation of 8000 to 12000 MW is studied.