G G L Ld L1 L2 L3 L4 L5 T1001 T1002 G5002 G5001 B1 B2 B3 B4 B5 B6

BUS_CON.CFG (Fixed file) BUS NO BUS SC IMP (OHM) (OFF LINE) DEV CONN

DEV_IMP.CFG (Fixed file) DEV_NOIMPEDANCE (OHM) (X ONLY) (INCLUDING GT) (INCLUDING GT)

REAL TIME VALUES FROM SCADA BUS_VOL.DAT BUS_NOVoltage in kV

NSP OUTPUT FROM SCADA DEV_STS.DAT DEV_NOStatus 1Energised 2 3De-Energised 4Energised Energised 1002Energised 5001Energised 5002De- Energised

Z SC1 Z SC2 ZLZL BUS 1 BUS 2 INITIAL CONDITION, ZSC1 & ZSC2 INCLUDES EFFECT OF Z L

Z1 Z2 ZLZL BUS 1 BUS 2 CALCULATE INTERMEDIATE VALUES OF Z1 & Z2 DURING ITERATION EXCLUDING EFFECT OF Z L Z1 & Z2 COMPUTED BY SOLVING THE FOLLOWING NON-LINEAR EQUATION (LOOKS SIMPLE – TRY SOLVING) ZSC1 = Z1 || ZL + Z2 ZSC2 = Z2 || ZL + Z1 WHERE ZSC1, ZSC2, ZL ARE KNOWN COMPLEX PART OF ALGORITHM

Z1 Z2 ZLZL BUS 1 BUS 2 ITERATION RESULT, NEW ZSC1 IS COMPUTED INCLUDING THE EFFECT OF Z L DEPENDING UPON LINE STATUS. IF LINE STATUS IS De-Energised, NEW ZSC1=Z1 other wise NEW ZSC1 = Z1 || Z L + Z2 Z SC1 BUS 1

INITIAL VALUES OF ALL BUS SHORT CIRCUIT IMPEDANCE ARE COMPARED WITH THE CALCULATED VALUES, ON REACHING THE TOLERANCES, COMPUTE SHORT CIRCUIT MVA OF EACH BUSES SHORT-CIRCUIT MVA = KV * KV / ZSC Z1 AND Z2 COMPUTATION IS TAKEN FOR LINE ONLY AS EXAMPLE. IN FINITE ELEMENT METHOD – THE PROCESS IS SAME and REPEATED FOR ALL DEVICES CONNECTED TO THE BUS.

SHORT-CIRCUIT LEVEL - TO SCADA BUS_SCL.DAT BUS_NOSC MVA