Synchrophasor Initiative in India - erldc

SYNCHROPHASORS - INITIATIVE IN INDIA JUNE 2012In the Southern Regional power system, analysis of several grid disturbances [Reference 1] thatoccurred in 2002 revealed that that the disturbance had occurred whenever the angularseparation between 400 kV Ramagundam (generation complex) and 400 kV Neyveli (loadcentre) generally exceeded 60 degrees (Refer figure: 1).Likewise in the Northern Region, the experience of several incidents of separation of theEastern (pit head generation pocket) and Western part (load centre) of the Northern Regionrevealed that the angular separation between 400 kV Rihand (in South eastern part) and 400 kVDadri (in the Western part) and the power flow across the East-West transmission corridor wasrequired to be maintained within 40 degrees and 3500 MW respectively (Refer figure 2).Figure 2: Angular separation between Rihand and Dadri on 26-July-2004The above two experiences established that the angular separation between different nodes inthe grid is an indicator of the stress in the grid and the need for monitoring it in real-time wasfelt. However, since the direct measurement of phase angles was not available through SCADA,the angular separation across the HVDC Rihand-Dadri bipole was computed externally andmade available to the operator (refer figure 3).Thereafter, an experiment with telemetry of measured phase angle separation between theadjacent 400 kV buses of an HVDC Vindhyachal back to back station within the synchronoussystem was carried out in 2007. Initially a voltage transducer was placed at HVDC Vindhyachalback-to-back station and the 400 kV R-phase voltage of the Vindhyachal North bus andVindhyachal West bus was given as input. The vector difference of the two voltages wastelemetered (through existing SCADA) at the Northern Regional Load Despatch Centre and thePOSOCO Page 16 of 143