Synchrophasor Initiative in India - erldc

SYNCHROPHASORS - INITIATIVE IN INDIA JUNE 20125.7 Computation of System parameters5.7.1 Case Study 38: Computation of System Inertia constantAn incident of multiple tripping of lines & loss of generation of 1580 MW occurred at Dadri(NTPC) complex on 10 th July 2011 at 13:55hrs. The rate of change of frequency (df/dt) recordedby PMU’s was utilized to calculate the inertia constant of NEW grid.Figure 129: df/dt profile during tripping of Dadri NTPC on 19th July 2011Inertia Constant (H) = (∆P / P) x f 0 /(2 x df/dt)Where,∆P – Generation lossP – Size of N.E.W gridf 0 – frequency before disturbanceH = (1580 / 65300) x 50.02 / (2 x 0.08)H= 7.5 secNote: for the purpose of calculation of df/dt the noise observed during initial period ofdisturbances were ignored. The df/dt was computed based on 160ms PMU data.POSOCO Page 125 of 143