POWER GRID CORPORATION OF INDIA LTD.

1. POWER GRID CORPORATION OF INDIA LTD. SRLDC,BANGALORE

2. EXCERPTS FROM CERC ORDER DATED 26.06.2002 “In the interest of security and safety of the regional grid, we, therefore, feel that some parts of the States indulging in overdrawals have to be isolated/islanded and supplied from the State's own resources at whatever frequency they want to operate at the risk of their own machinery & equipment; but not through the Inter-State Transmission System or Inter-State Generation System.”

3. EXCERPTS FROM CERC ORDER DATED 26.06.2002 “We, therefore, consider that a Committee ……… may go into the technical and commercial aspects of isolating/islanding some parts of the system, without damage to theRegional grid, in detail .” VIEW THE ORDER

4. SECTION 55 ELECTRICITY (SUPPLY) ACT, 1948 AMENDED 1998 2) The Regional Load Despatch Centre shall give the apex body to ensure integrated operation of the power system in the concerned region. 3) The Regional Load Despatch Centre may give such directions and exercise such supervision and control as may be required for ensuring integrated grid operation and for achieving the maximum economy and efficiency in the operation of the power system in that state

5. IEGC-Chapter - 3 Clause - 3.5 • (i) As a general rule, the ISTS shall be capable of withstanding and be secured against the following contingency outages without necessitating load shedding or rescheduling of generation during Steady State Operation :- • Outage of a 132 kV D/C line or • Outage of a 220 kV D/C line or, • - Outage of a 400 kV S/C line or, • - Outage of single Interconnecting Transformer, or • - Outage of one pole of HVDC Bipole line, or • - Outage of 765 kV S/C line.

6. IEGC-Chapter - 6 Clause - 6.2System Security Aspects: a ) All Regional constituents shall endeavor to operate their respective power systems and Power Stations in synchronism with each other at all times, such that the entire system within a Region operates as one synchronised system.

7. IEGC-Chapter - 6 Clause - 6.2System Security Aspects: • b) No part of the grid shall be deliberately isolated from the rest of the Regional Grid,except • I) under an emergency, and conditions in which such isolation would prevent a total grid collapse and/or enable early restoration of power supply • II) when serious damage to a costly equipment is imminent and such isolation would prevent it • III) when such isolation is specifically instructed by RLDC. Complete synchronisation of grid shall be restored as soon as the conditions again permit it. The restoration process shall be supervised by RLDC, as per operatingprocedures separately formulated.

8. IEGC Chapter - 6 Clause - 6.2 C )No important element of the Regional gridshall be deliberately opened or removed from service at any time, except when specifically instructed by RLDC or with specific and prior clearance of RLDC. The list of such important grid elements on which the above stipulations apply shall be prepared by the RLDC in consultation with the constituents, and be available at RLDC/SLDCs. In case of opening/ removal of any important element of the grid under an emergency situation, the same shall be communicated to RLDC at the earliest possible time after the event.

9. EXCERPTS FROM MANUAL ON TRANSMISSION PLANNING CRITERIA - CEA • 2. PLANNING PHILOSOPHY & GENERAL GUIDELINES • 2.1 The transmission system shall be planned on the basis of regional self- sufficiency with an ultimate objective of evolving a National Power Grid.

10. GENERAL ISSUES • MODUS OPERANDI- • INITIATION OF THE SCHEME AND NORMALISATION • YARDSTICK FOR INITIATING ISOLATION/ISLANDING • HOW LONG SHOULD SUCH ISOLATION LAST? • SYSTEM CONSTRAINTS? • WHO DECIDES?

11. GENERAL ISSUES CONTD….. • MODUS OPERANDI- • LOAD CONTROL /SWITCHING TO BE DONE BY STATE SYSTEM – LOGISTICS? • WHO DECIDES WHAT LOADS ARE TO BE ADDED/REMOVED? • VARIATIONS OF LOAD INVOLVES MANY SWITCHING OPERATIONS – WHO WILL CO-ORDINATE THE SAME? • INNUMERABLE HYPOTHETICAL COMBINATIONS POSSIBLE FOR ISLANDING

12. GENERAL ISSUES CONTD…. • MODUS OPERANDI- • CONCURRENT APPLICABILITY TO OTHERS SYSTEMS? • IN CASE OF OVERDRAWALS BY TWO OR THREE CONSTITUENTS AT LOW FREQUENCY-WOULD THE SCHEME BE APPLIED SIMULTANEOUSLY? • THIS WOULD REQUIRE CO-ORDINATION OF MANY SWITCHING OPERATIONS.

13. ISOLATION OF GRIDISSUES INVOLVED • OPERATION ISSUES • SCHEDULING ISSUES • PROTECTION ISSUES • COMMERCIAL ISSUES • STABILITY ISSUES • SHORT CIRCUIT LEVELS • L-INDEX – VOLTAGE STABILITY • ANGULAR STABILITY REPORT OF HIGH COURT APPOINTED COMMITTEE

14. 47.7 HZ 51.5 HZ OPERATIONAL ISSUES • A PART OF LOAD(400-3000MW SAY) ISOLATED. • STABILITY ISSUES • LOWER SHORT CIRCUIT LEVELS IN BOTH PARTS LEADING TO VOLTAGE EXCURSIONS • LOWER INERTIA - LEADING TO FREQUENCY EXCURSIONS .............CONTD

15. OPERATIONAL ISSUES • OPERATIONAL FLEXIBILITY LOST • DIVERSITY WILL REMAIN UNUTILISED • TRANSITION BETWEEN PEAK AND OFF-PEAK - DIFFICULT TO MANAGE • LINE LOADINGS – A PROBLEM DURING LOAD CHANGE OVER IN AP – HYDRO FLEXIBILITY UNAVAILABLE • FREQUENCY RISE DIFFICULT TO CONTAIN IN BOTH BLOCKS • PREDOMINANT THERMAL – LOWER INERTIA • Df/dt WILL BE SHARP • VOLTAGE AND FREQUENCY EXCURSIONS –EXTREME • COMPLEXITY INVOLVED IN SWITCHING

16. PROTECTION ISSUES • DRASTIC REDUCTION IN SC LEVELS- OCR SETTINGS? • FREQUENCY AND VOLTAGE EXCURSIONS- v/f SETTINGS? • LOAD ENCROACHMENT PROBLEMS – LOW VOLTAGE - LOADING • POWER SWING

17. ISSUES TO BE EXAMINED FOR ISOLATION • SCHEDULING PROBLEMS- • CONTRACTION/EXPANSION OF ISLAND TO BE DONE WITH CHANGING SCHEDULES • COMPLEXITY INVOLVED IN SWITCHING • FORCED OVERDRAWALS – A QUANDRARY THAT MAY BE UNAVOIDABLE • STATE SYSTEM – INABILITY TO DRAW ENTITLEMENT • LOAD MANAGEMENT/SWITCHING OPERATION – STILL IN STATE PURVIEW

18. ISSUES TO BE EXAMINED FOR ISOLATION CONTD.... • SCHEDULING PROBLEMS- • DRAWAL PATTERN VARIATION –:(MIN/MAX IN %) • CONTRACTION AND EXPANSION OF ISLAND • COMMERCIAL IMPLICATION- OD/UD 3D LOAD PROFILE

19. COMMERCIAL ISSUES • INABILITY TO DRAW AS PER ENTITLEMENT DUE TO INSUFFICIENT LOAD IN ISGS/ISTS BLOCK :- • STATE MAY BE FORCED TO UNDERDRAW FROM ISGS AND FORCED TO GENERATE AT COSTLY IPP’S/DEPLETED HYDRO – COMMERCIAL IMPLICATION?. • OVERDRAWAL MAY CONTINUE FORCING OTHER CONSTITUENTS TO COMMIT COSTLY GENERATION

20. SHORT CIRCUIT LEVELS – RELEVANCE TO GRID OPERATION • SC LEVELS ARE AN INDICATOR OF THE ‘STRENGTH’ OF THE BUS TO REACTIVE POWER FLUCTUATIONS • HIGHER SC LEVELS – BUS IS MORE STABLE – LIMITS VOLTAGE EXCURSIONS • HIGHER SC LEVELS- BUS IS WELL INTERCONNECTED-PROXIMITY OF GENERATORS • ESPECIALLY IMPORTANT DURING RESTORATION.

21. SHORT CIRCUIT LEVELS – RELEVANCE TO GRID OPERATION • AN EXAMPLE:- • CHARGING A 300 KM LINE FROM A 2000 MVA 400 KV BUS WOULD INCREASE THE VOLTAGE BY 33 KV • CHARGING A 300 KM LINE FROM A 6000 MVA 400 KV BUS WOULD INCREASE THE VOLTAGE BY 11 KV SHRT CKT STUDY RESULT

22. L INDEX • INDICATES THE PROXIMITY TO VOLTAGE COLLAPSE • IF THE INDEX APPROACHES 1 THEN THE BUS IS INCREASINGLY VULNERABLE TO VOLTAGE COLLAPSE • DERIVED FROM LOAD FLOW JACOBIAN MATRIX • SHOULD BE GENERALLY WITHIN 0.3 DURING NORMAL OPERATION FOR SR GRID. • GENERALLY IN LINE WITH WHAT IS OBSERVED BY THE SYSTEM OPERATORS L INDEX STUDY RESULT L INDEX STUDY 400 KV SUMMARY

23. L INDEX

25. SCIENTIFIC SETTLEMENT SYSTEM? ISGS KAR AP KER TN

27. LINKS SR GRID MAP KAR ISL CASE3 TN ISL CASE1 AP GRID MAP KARNATAKA GRID MAP KERALA GRID MAP TN GRID MAP SHORT CKT STDY RESULTS 400 KV L INDEX STUDY RESULTS 3D DEMAND SR JUNE 2002 3D DEMAND SR MAY2002 3D DEMAND SR MARCH 2002 SHORT CKT STDY RESULTS 230 KV SHORT CKT STDY RESULTS 220 KV

28. ISOLATION OF PART OF KARNATAKA: CASE STUDY GRID MAP • CASE 1: SOMANAHALLY TRANSFORMER CONNECTED TO AP-TN-KER GRID AND RADIALLY FEEDING 700MW LOAD, KAIGA EMBEDDED IN KARNATAKA SYSTEM.400 KV RTPS-N’SAGAR OPEN • CASE 2: CASE 1 WITH KAIGA ISLANDED • CASE 3: SPLIT BUS AT RTPS, KAIGA & 400KV UNITS OF RAICHUR WITH AP-KER-TN-KOLAR-SOMANAHALLI-HOODY-GUTTUR SYSTEM. SOMANAHALLY AND HOODY RADIALLY FEEDING BANGALORE LOADS EXCEPT PEENYA.

29. CASE 1 BANGALORE LOADS ON AP-TN-KER GRID LOAD 3000 MW LOW VOLTAGE ZONE ABOUT 700 MW ON AP-TN-KER GRID

30. KARNATAKA-SC LEVELS IN MVA

31. ISOLATION OF PART OF KERALA AND TAMILNADU: CASE STUDY • TAMILNADU : TTPS, BALAJI POWER,WIND, NILAGIRIS HYDRO, KADAMPARAI HYDRO IN ISOLATED PORTION. AP-KAR-KER AND N.TAMILNADU(NEYVELI-MAPS-ETS-NMTPS-MTPS – GMR) IN ONE BLOCK • KERALA- SPLIT BUS AT EDAMON AND THRISSUR WITH LOADS TAKEN RADIALLY AT BOTH POINTS

32. TAMILNADU AND KERALA SC LEVELS IN MVA

33. OPERATIONAL ISSUESKARNATAKA • KAIGA REMAINS EMBEDDED IN ISOLATED PORTION OF KARNATAKA • FREQUENT HOUSE LOADING AND POISONING OUT - EXPECTED. • KAPS TO REDUCE GENERATION BY 40-50 MW TO PREVENT HUNTING • DEPLETED HYDRO POSITION IN ISOLATED PART: • PEAKING HYDRO TO BE RUN AS BASE STATION • STORAGE POSITION ALREADY CRITICAL • EXTREMELY LOW VOLTAGES TO BE EXPECTED IN SOUTH KARNATAKA.

34. DELIVERING CGS ENTITLEMENT TO KARNATAKA • KPTCL’S CGS ENTITLEMENT WITH FULL GENERATION AT NTPC,NLY,KAPS AND ONE UNIT AT MAPS IS AND WITH ALLOCATION OF 156 MW ER AND 100 MW PTC POWER = 1206 MW • GOA’S ENTITLEMENT TO BE WHEELED BY KPTCL = 94 MW. • TOTAL ENTITLEMENT OF KPTCL = 1310 MW • AS KAIGA GENERATION OF 400 MW IS EMBEDDED KPTCL HAS TO IMPORT 910 MW • AT 330 KV/400 MVAR IMPORT THE CAPACITY OF SOMANAHALLI TRANSFORMER IS 720 MW

35. DELIVERING CGS ENTITLEMENT TO KARNATAKA • KPTCL’S CGS ENTITLEMENT WITH FULL GENERATION AT NTPC,NLY, ONE UNIT AT KAPS AND MAPS IS AND WITH ALLOCATION OF 156 MW ER AND 100 MW PTC POWER = 1140 MW • GOA’S ENTITLEMENT TO BE WHEELED BY KPTCL = 94 MW. • TOTAL ENTITLEMENT OF KPTCL = 1234 MW • AS KAIGA GENERATION OF 200 MW IS EMBEDDED KPTCL HAS TO IMPORT 1034 MW • AT 330 KV/400 MVAR IMPORT THE CAPACITY OF SOMANAHALLI TRANSFORMER IS 720 MW • DIFFICULTY IN DELIVERING ENTITLEMENT • LOADS AT SOMANAHALLI TO BE REARRANGED DEPENDING ON KAPS GENERATION