PRESENTATION ON TRIPPING SCHEMES OF TALCHER STAGE-II UNITS (4X500MW) IN THE EVENT OF TALCHER – KOLAR HVDC POLE(S) OUTAGE BY NATIONAL THERMAL POWER CORPORATION

GLIMPSES OF GENERATION AT TALCHER STPP

PRESENT SCENARIO GRID CAPACITY GRID CAPACITY ER GRID :10000 MW ER GRID :10000 MW WR GRID :30000 MW WR GRID :30000 MW SR GRID :23000 MW SR GRID :23000 MW INTER GRID CONNECTIONS INTER GRID CONNECTIONS  ER – WR SYNCHRONOUSLY LINKED THROUGH ROURKELA – RAIPUR 400 kV D/C ROURKELA – RAIPUR 400 kV D/C BUDHIPADAR – KORBA 220 kV 3 ckts. BUDHIPADAR – KORBA 220 kV 3 ckts.  ER – SR ASYNCHRONOUSLY LINKED THROUGH TALCHER – KOLAR HVDC BIPOLE (2X 1000 MW) TALCHER – KOLAR HVDC BIPOLE (2X 1000 MW) JEYPORE – GAZUWAKA HVDC BACK TO BACK (2X500MW ) JEYPORE – GAZUWAKA HVDC BACK TO BACK (2X500MW )

SCENARIO DURING HVDC POLE(S) OUTAGE IN CASE OF SINGLE POLE/BIPOLE OUTAGE OF TALCHER – KOLAR HVDC LINK, ADDITIONAL POWER OF IN CASE OF SINGLE POLE/BIPOLE OUTAGE OF TALCHER – KOLAR HVDC LINK, ADDITIONAL POWER OF 600 MW ( I POLE OUT) / 1850 MW (BIPOLE OUT) 600 MW ( I POLE OUT) / 1850 MW (BIPOLE OUT) WILL BE INJECTED INTO THE ER-WR GRID WILL BE INJECTED INTO THE ER-WR GRID THE ADDITIONAL POWER IN THE ER-WR SYSTEM WILL BE ABSORBED IN THE ER / WR GRID IN THE RATIO OF 30:70 THE ADDITIONAL POWER IN THE ER-WR SYSTEM WILL BE ABSORBED IN THE ER / WR GRID IN THE RATIO OF 30:70 (PROPORTINATE TO THE RESPECTIVE GRID CAPACITY) (PROPORTINATE TO THE RESPECTIVE GRID CAPACITY) AS ER – WR LINKS NORMALLY REMAINS LOADED TO ITS LIMITS, THE ABOVE ADDITIONAL POWER MAY TRIP THE ER-WR LINKS AND CAUSE FURTHER DISTURBANCE IN THE SYSTEM. AS ER – WR LINKS NORMALLY REMAINS LOADED TO ITS LIMITS, THE ABOVE ADDITIONAL POWER MAY TRIP THE ER-WR LINKS AND CAUSE FURTHER DISTURBANCE IN THE SYSTEM.

BASIC PRESUMPTIONS A) ER- WR GRID CAN ABSORB ADDITIONAL POWER OF 450 MW WITH OUT CAUSING GRID DISTURBANCE B) IN CASE OF SINGLE POLE OUTAGE OF HVDC THE HEALTHY POLE CAPACITY CAN AUTOMATICALLY BE INCREASED TO 1250 MW FROM 1000 MW C) FOR BOTH POLES HEALTHY CONDITION, POWER FLOW SHALL BE LIMITED TO 1700 MW 1700 MW OR OR TALCHER ST–II EX-BUS GENERATION, TALCHER ST–II EX-BUS GENERATION, WHICH EVER IS HIGHER WHICH EVER IS HIGHER D) FOR SINGLE POLE HEALTHY CONDITION, POWER FLOW SHALL BE LIMITED TO 450 MW 450 MW OR OR TALCHER ST -II EX-BUS GENERATION TALCHER ST -II EX-BUS GENERATION WHICH EVER IS HIGHER, LIMITTED TO SINGLE POLE CAPACITY WHICH EVER IS HIGHER, LIMITTED TO SINGLE POLE CAPACITY

PROPOSED SCHEME TO ENSURE GRID STABILITY a) BOTH POLES WERE HEALTHY AND ONE POLE GOES OUT INSTANT TRIPPING OF UNIT #6, (ONE OF THE FOUR STAGE-II UNITS) IF EX BUS GENERATION IS MORE THAN 1700MW INSTANT TRIPPING OF UNIT #6, (ONE OF THE FOUR STAGE-II UNITS) IF EX BUS GENERATION IS MORE THAN 1700MW b) BOTH POLES WERE HEALTHY AND BOTH POLES GO OUT IF EX BUS GENERATION IS MORE THAN 1100 MW IF EX BUS GENERATION IS MORE THAN 1100 MW UNITS #5 & #6 TRIPPED INSTANTANEOUSLY UNITS #5 & #6 TRIPPED INSTANTANEOUSLY UNIT #4 TRIPPED AFTER 250 m sec UNIT #4 TRIPPED AFTER 250 m sec IF EX BUS GENERATION IS MORE THAN 550 MW IF EX BUS GENERATION IS MORE THAN 550 MW  UNIT # 5 TRIPPED INSTANTANEOUSLY  UNIT # 4 TRIPPED AFTER 250 m sec  UNIT # 6 TRIPPED AFTER 500 m sec NOTE: STAGGERED TRIPPING IS ADOPTED TO ALLOW THE POWER SUMMATED SIGNAL RESETTING SUMMATED SIGNAL RESETTING

Inter Trip Scheme

PRESENT SITUATION  PGCIL HAS ALREADY TAKEN ACTION FOR UPGRADING HVDC POLE CAPACITY TO 1250 MW FROM 1000 MW. THIS DOES NOT MEET N-1 CONTINGENCY CRITERIA.  AS A FOLLOW UP, IN SREB MTG DTD ALL THE CONSTITUENTS AGREED TO THE NEED FOR BACK UP TRANSMISSION SYSTEM. FOR THIS, PGCIL NEEDS TO BE PERSUADED FOR PUTTING UP PROPOSAL IN NEXT SCM.

PROPOSED SOLUTION TO AVOID ANY UNIT TRIPPING AT TALCHER UNDER SINGLE POLE OUTAGE TILL BACK UP TRANSMISSION SYSTEM IS MADE AVAILABLE, FOLLOWING OPTION NEED TO BE ADOPTED: TO AVOID ANY UNIT TRIPPING AT TALCHER UNDER SINGLE POLE OUTAGE TILL BACK UP TRANSMISSION SYSTEM IS MADE AVAILABLE, FOLLOWING OPTION NEED TO BE ADOPTED: FLOW ON TALCHER-KOLAR IS KEPT IN THE RANGE OF MW FLOW ON TALCHER-KOLAR IS KEPT IN THE RANGE OF MW MW POWER IS DIVERTED FROM TALCHER ON GAZUWAKA HVDC (PGCIL HAVE PLANNED BERHAMPUR-GAZUWAKA 400 KV D/C LINE TO FURTHER STRENGTHEN THIS CORRIDOR, WHICH IS YET TO BE AGREED BY SR) MW POWER IS DIVERTED FROM TALCHER ON GAZUWAKA HVDC (PGCIL HAVE PLANNED BERHAMPUR-GAZUWAKA 400 KV D/C LINE TO FURTHER STRENGTHEN THIS CORRIDOR, WHICH IS YET TO BE AGREED BY SR)

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