POWER GRID CORPORATION OF INDIA LTD.

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POWER GRID CORPORATION OF INDIA LTD.
SRLDC,BANGALORE
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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.

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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 the Regional grid, in detail .

VIEW THE ORDER
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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
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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.

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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.
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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 operating procedures
  separately formulated.

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IEGC Chapter - 6 Clause - 6.2 C ) No important
element of the Regional grid shall 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.
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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.

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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?

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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

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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.

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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
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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

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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

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PROTECTION ISSUES

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

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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

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ISSUES TO BE EXAMINED FOR ISOLATION CONTD....

• SCHEDULING PROBLEMS-
• DRAWAL PATTERN VARIATION (MIN/MAX IN )
• CONTRACTION AND EXPANSION OF ISLAND
• COMMERCIAL IMPLICATION- OD/UD

STATE SYSTEM MIN/MAX IN
ANDHRAPRADESH 75-85
KARNATAKA 55-65
KERALA 55-60
TAMILNADU 80-85
3D LOAD PROFILE
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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 IPPS/DEPLETED HYDRO
  COMMERCIAL IMPLICATION?.
• OVERDRAWAL MAY CONTINUE FORCING OTHER
  CONSTITUENTS TO COMMIT COSTLY GENERATION

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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-PROXI
  MITY OF GENERATORS
• ESPECIALLY IMPORTANT DURING RESTORATION.

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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
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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
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L INDEX
GOOTY 0.3126 AP
CUDDAPAH 0.268 AP
HYDERABAD 0.236 AP
KHAMMAN 0.1794 AP
NUNNA 0.1693 AP
RAMAGUNDAM 0.1197 AP
SIMHADRI 0.1177 AP
BANGALORE 0.3431 KAR
HOODY 0.3175 KAR
NELAMANGALA 0.3101 KAR
KOLAR 0.3043 KAR
DAVANGERE 0.2157 KAR
MUNIRABAD 0.1721 KAR
RAICHUR 0.0804 KAR
TRICHUR 0.2262 KER
HOSUR 0.2539 TN
SALEM 0.2011 TN
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SCIENTIFIC SETTLEMENT SYSTEM?
ISGS
KAR
AP
KER
TN
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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
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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-NSAGAR 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-GUT
  TUR SYSTEM. SOMANAHALLY AND HOODY RADIALLY
  FEEDING BANGALORE LOADS EXCEPT PEENYA.

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CASE 1 BANGALORE LOADS ON AP-TN-KER GRID
LOAD 3000 MW
LOW VOLTAGE ZONE
ABOUT 700 MW ON AP-TN-KER GRID
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KARNATAKA-SC LEVELS IN MVA
ISLANDING IN KARNATAKA SYSTEM ISLANDING IN KARNATAKA SYSTEM ISLANDING IN KARNATAKA SYSTEM KARNATAKA KARNATAKA KARNATAKA
STN_NAME STATE BASE CASE CASE1 CASE2 CASE3
RST4 AP 8760 8378 8371 8194
TPL4 AP 6768 5926 5916 5697
CNP4 AP 5055 4782 4776 4747
GTN4 AP 2936 3027 3018 2789
KOLAR4 KAR 6479 5362 5358 5868
RTPS4 KAR 5859 3962 3692 3149
SOMN4 KAR 5540 4394 4390 4850
HOODY4 KAR 5536 1522 1305 4911
NLMNG4 KAR 4818 1656 1423 3979
DVGRE4 KAR 4349 2545 2120 2890
GDHL4 KAR 3767 2777 2546 2330
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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

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TAMILNADU AND KERALA SC LEVELS IN MVA
      KERALA TN
STN_NAME STATE BASE CASE CASE1 CASE1
RST4 AP 8760 8740 8725
CNP4 AP 5055 5014 4987
SOMN4 KAR 5540 5441 5312
KOLAR4 KAR 6479 6537 6526
TRICH4 KER 3838 2724 3239
N2MIN4 TN 10556 10128 9828
NLYEU4 TN 10223 9818 9537
SALEM4 TN 8119 7639 6523
SPBUDUR4 TN 7011 6923 6895
TRICHY4 TN 6661 6266 5654
MADURAI4 TN 5755 5251 4094
HOSUR4 TN 5474 5346 5277
UDMLPT4 TN 5433 4363 4032
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OPERATIONAL ISSUES KARNATAKA

• 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.

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DELIVERING CGS ENTITLEMENT TO KARNATAKA

• KPTCLS 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
• GOAS 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

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DELIVERING CGS ENTITLEMENT TO KARNATAKA

• KPTCLS 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
• GOAS 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

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GENERAL ISSUES CONTD...

• A POSSIBLE SCENARIO-

AP
KAR
CGS AND LOADS
KERALA
TAMILNADIU