The document discusses guidelines for transmission system planning in India. It outlines that: - The Central Electricity Authority is responsible for preparing transmission plans and coordinating planning agencies according to the Electricity Act 2003. - The transmission system consists of the inter-state transmission system (ISTS) managed by the Central Transmission Utility and intra-state transmission systems (Inra-STS) managed by State Transmission Utilities. - Transmission planning involves power flow studies, short circuit studies, and stability studies to ensure system security, reliability and that all parameters remain within limits under normal ('N-0') and contingency ('N-1' and 'N-1-1') conditions.

1. SUBMITTED BY
ARUN MURALEEDHARAN
ROLL NO 12281
ELECTRICAL AND ELECTRONICS ENGINEERING
NATIONAL INSTITUTE OF TECHNOLOGY
HAMIRPUR

2.  CENTRAL ELECTRICITY AUTHORITY RESPONSIBLE FOR
PREPARATION OF TRANSMISSION PLANS.
 AND FOR COORDINATING ACTIVITIES OF PLANNING AGENCIES AS
PER ELECTRICITY ACT 2003.
 CENTRAL TRANSMISSION UTILIY RESPONSIBLE FOR INTER STATE
TRANSMISSION SYSTEM.
 STATE TRANSMISSION UTILITY RESPONSIBLE FOR INTRA-STS.
 BOTH ISTS AND INTRA-STS ARE INTERCONNECTED TO FORM THE
NATIONAL GRID.
 VOLTAGE LEVELS FOR ISTS: 132kV AND INTRA-STS: 66kV
 CRITERIA TO BE USED FOR SYSTEMS PLANNED AFTER FEB 2013
 EXISTING SYSTEMS WILL BE REVIEWED ACCORING TO THIS AND
ACCORDINGLY ADJUSTMENTS TO BE MADE.

3. a) TRANSMISSION SYSTEM SERVES AS INTERCONNECTION BETWEEN
SOURCE AND LOAD. ISTS AND INTRA-STS ARE THE CLASSIFICATION OF
INDIAN TRANSMISSION SYSTEMS. FORMER IS TOP LAYER OF NATIONAL
GRID, THE LATTER LIES BELOW IT.
b) TRANSMISSION SYSTEM IS AUGMENTED TO CATER TO LONG TERM
POWER REQUIREMENTS. E.g INCREASE IN DEMAND ETC.
c) TRANSMISSION CUSTOMERS AND UTILITIES GIVE THEIR
TRANSMISSION REQUIREMENT AND PRDUCTION SO AS TO PREVENT
LOAD CONGESTION AND OTHER SUCH PROBLEMS. CUSTOMERS SHALL
PROVIDE REASON FOR THEIR TRANSMISSION CONSUMPTION.
d) LONG TERM APPLICANTS ARE SUPPOSED TO SUBMIT THEIR
REQUIREMENTS TO CTU/STU TO MAKE AVAILABLE THE REQUIRED
DEMAND.
e) FOR EVACUATION OF POWER FROM HYDRO PROJECTS TI BE DONE
RIVER BASIN WISE CONSIDERING THE IDENTIFIED GENERATION
PROJECTS AND POWER POTENTIAL.
f) FOR CONGESTED AREAS (URBAN AREAS) OR WITH DIFFICULT TERRAIN
ETC, TRANSMISSION CORRIDOR MAY BE PLANNED FOR LONG TERM
OPTIMISATION KEEPING IN MIND RIGHT OF WAY AN COST. CAN BE
DONE BYE USING TECHNOLOGY LIKE HVDC,GIS OR USING MULTI
CIRCYUIT TOWERS FOR STRINGING CIRCUITS.

4. h) STU ACTS AS NODAL AGENCY FOR INTRA-STS PLANNING. STU SHALL BE
SINGLE CONTACT POINT FOR ISTS.
i) NORMALLY INTRA STATE ENTITIES TO BE SUPPLIED BY INTRA STATE
NETWORK EXCEPT IN EXCEPTIONAL CASES, THEN IT IS SUPPLIED BY ISTS.
THEN THIS CONNECTION CAN ALSO BE USED BY OTHER INTER STATE
ENTITIES.
j) STU COORDINATE WITH URBAN PLANNING AGENCIES, SEZ DEVELOPERS
AND KEEP LAND FOR FURTHER DEVELOPMENT FOR LONG TERM
REQUIREMENTS.
k) SYSTEM PARAMETERS AND LOADING OF SYSTEM ELEMENTS TO REMAIN
WITHIN PRESCRIBED LIMITS.
l) TO ENSURE SECURITY OF GRID, DURING TIMES OF FAILURE, SUITABLE
DEFENSE MECHANISMS SHOULD BE ADOPTED. SUCH AS LOAD SHEDDING,
GENERATION RESCHEDULING, ISLANDING ETC.
m) CRITICAL LOADS- RAILWAYS, METRO RAILM AIRPORTS, REFINERIES,
PLANTS ETC PLAN THEIR CONNECTION WITH GRID WITH 100%
REDUNDANCY.
n) PLANNED TRANSMISSION CAPACITY WOULD BE FINITE. THERE WILL BE
POSSIBILITY OF CONGESTION IF LOAD IS MORE THAN ANTICIPATED.
o) COMMUNICATION SYSTEM FOR NEW SUBSTATIONS AND GENERATING
STATION SHOULD BE PLANNED BY CTU/STU.

5. h) THERE SHOULD BE STRENGTHENING OF TRANSMISSION NETWORK
WHOSE CHOICES SHOULD BE BASED ON COST, RELIABILITY, RIGHT
OF WAY, LOSSES ETC
 ADDITION OF NEW TRANSMISSION LINE OR SUBSTATIONS
 APPLICATION OF SERIES CAPACITORS, FACTS DEVICES ETC TO
INCREASE POWER TRANSFER CAPABILITY
 UPGRADATION OF EXISTING AC TRANSMISSION LINES TO HIGHER
VOLTAGE USING SAME RIGHT OF WAY
 RE-CONDUCTORING OF EXISTING AC LINES WITH HIGHER AMPACITY
CONDUCTORS
 USAGE OF MULTI VOLTAGE LEVEL AND MULTI CIRCUIT LINES
 USE OF NARROW BASE TOWERS AND POLE TYPE TOWERS IN
URBAN/SEMI URBAN AREAS KEEPING IN COST AND RIGHT OF VIEW
OPTIMISATION.
 USE OF HVDC TRANSMISSION
 USE OF GIS/HYBRID SWITCHGEAR.

7.  NORMAL OPERATION, ‘N-0’, ALL ELEMENTS ARE AVAILABLE.
ALL PARAMETERS SUCH AS VOLTAGES, LOADINGS, FREQUENCY
SHOULD REMAIN WITHIN PERMISSIBLE LIMITS.
 ‘N-1’ DISTURBANCE; MORE PROBABLE DISTURBANCE. AGAIN
ALL PARAMETERS SHOULD REMAIN WITHIN PERMISSIBLE
LIMITS.
 SECOND CONTINGENCY, LESS PROBABLE, ‘N-1-1’, HERE SOME
OF THE EQUIPMENTS MAY BE LOADED UPTO EMERGENCY
LIMITS. FOR SUCH A CONTINGENCY, METHODS SUCH AS LOAD
SHEDDING/RE-SCHEDULING OF GENERATION MAY HAVE TO BE
APPLIED EITHER MANUALLY OR THROUGH AUTOMATIC
SYSTEM PROTECTION SCHEMES. TO BE APPLIED WITHING 1.5
HRS AFTER DISTURBANCE.

8.  NORMAL THERMAL AND VOLTAGE RATINGS: EQUIPMENT LIMITS WHICH
CAN BE SUSTAINED ON CONTINUOUS BASIS.
 EMERGENCY THERMAL AND VOLTAGE RATINGS: EQUIPMENT LIMITS
WHICH CAN BE TOLERATED FOR A SHORT TIME.
 LOADING LIMIT OF T.L/THERMAL LOADING LIMIT: DETERMINED BY
DESIGN PARAMETERS BASED ON AMBIENT TEMPERATURE, MAX
PERMISSIBLE CONDUCTOR TEMPERATURE, WIND SPEED, SOLAR
RADIATION, ABSORPTION COEFFICIENT, EMISSIVITY COEFFICIENT ETC.
SOME QUANTITIES ASSUMED TO BE FIXED DURING PLANNING.
 FOR T.L WITH DIFFERENT TYPES OF CONDUCTORS: BASED ON
CONDUCTOR TEMPERATURE LIMIT, RIGHT OF WAY OPTIMISATION,
LOSSES IN LINE, COST AND RELIABILITY CONSIDERATIONS ETC.
 THE LOADING LIMIT FOR AN INTER CONNECTING TRANSFORMER=NAME
PLATE READING. DURING PLANNING, MARGNS ARE KEPT.
 EMERGENCY THERMAL LIMITS FOR PLANNING= 110% OF THE NORMAL
THERMAL LIMITS.

9.  STEADY STATE VOLTAGE LIMITS. (MARGINS ARE ALSO CONSIDERED)
 TEMPORARY OVER VOLTAGE LIMITS DUE TO SUDDEN LOAD REJECTION
 SWITCHING OVER VOLTAGE LIMITS
800kV SYSTEM 1.9PU PEAK PHASE TO NEUTRAL ; (653kV=1P.U)
420kV SYSTEM 2.5PU PEAK PHASE TO NEUTRAL ; (343kV=1PU)

10. 1. ‘N-0’
 SYSTEM TESTED FOR ALL LOAD GENERATION SCENARIOS VIZ
ACTIVE POWER, REACTIVE POWER, GENERATION DISPATCHES AND
MODELLING.
 ALL EQUIPMENTS ON NORMAL THERMAL AND VOLTAGE RATINGS.
 ANGULAR SEPARATION BETWEEN ADJACENT BUSES ≤3O°.
2. ‘N-1’
2.1 STEADY STATE
 EQUIPMENTS AT NORMAL THERMAL AND VOLTAGE RATINGS AFTER
N-1 DISTURBANCE W/O LOAD SHEDDING/ RESCHEDULING OF
GENERATION
 ANGULAR ≤ 3O°.

11. 2.2 TRANSIENT STATE
 PERTURBATIONS CAN CAUSE TRANSIENTS WHICH ARE
OSCILLATORY IN NATURE, IF THE SYSTEM IS STABLE, THE
OSCILLATIONS WILL BE DAMPED.
 THE SYSTEM IS SAID TO BE STABLE IN WHICH SYNCHRONOUS
MACHINES, WHEN PERTURBED, RETURN TO THEIR ORIGINAL
STATE OR ANOTHER STATE ASYMPTOTICALLY WITHOUT
LOSING SYNCHRONISM
 THE TRANSMISSION SYSTEM SHALL BE STABLE AFTER ONE OF
FOLLOWING DISTURBANCES

12.  765 Kv LINE
i. PERMANENT 3-Φ TO GROUND FAULT; CLOSE TO THE BUS. (CLEARED IN 100ms)
ii. PERMANENT 1- Φ TO GROUND FAULT; CLOSE TO THE BUS.
SINGLE POLE OPENING(100ms) OF THE FAULTED PHASE; UNSUCCESSFUL
RECLOSURE (DEAD TIME 1 s) FOLLOWED BY 3 POLE OPENING (100ms) OF FAULTED
LINE
 400kV LINE
I. PERMANENT 3-Φ TO GROUND FAULT; CLOSE TO THE BUS (CLEARED IN 100ms)
II. PERMANENT 1- Φ TO GROUND; CLOSE TO THE BUS.
SINGLE POLE OPENING(100ms) OF THE FAULTED PHASE; UNSUCCESSFUL
RECLOSURE (DEAD TIME 1 s) FOLLOWED BY 3 POLE OPENING (100ms) OF FAULTED
LINE
 220kV/132kV
I. PERMANENT 3-Φ FAULT ON 1 CIRCUIT; CLOSE TO BUS; FAULT CLEARING TIME
=160ms (8 CYCLES; ASSUMING 3-POLE OPENING)
 FAULT IN HVDC CONVERTER STATION, RESULTING IN PERMANENT OUTAGE OF
ONE OF THE POLES OF HVDC BIPOLE.
 UNDER CONTINGENCY OF OUTAGE OF SINGLE LARGEST GENERATING UNIT OR A
CRITICAL GENERATING UNIT.

13. 3. ‘N-1-1’
FOLLOWING CONTINGENCIES UNDER ‘N-1-1’ CONDITION
 PERMANENT 1- Φ TO GROUND FAULT ON 400kV LINE; CLOSE TO THE
BUS. SINGLE POLE OPENING(100ms) OF FAULTED PHASE; UNSUCCESSFUL
RECLOSURE (DEAD TIME 1 s) FOLLOWED BY 3 POLE OPENING (100ms) OF
FAULTED LINE
 TEMPORARY 1- Φ TO GROUND FAULT ON 765kV LINE CLOSE TO THE BUS .
SINGLE POLE OPENING (100ms) OF FAULTED PHASE & UNSUCCESSFUL
RECLOSURE ( DEAD TIME 1 s)
 220kV/132kV NETWORKS, PERMANENT 3-Φ FAULT ON 1 CIRCUIT, CLOSE
TO A BUS, FAULT CLEARING TIME OF 160ms (8 CYCLES; ASSUMING 3-
POLE OPENING)
 SUCCESSFULLY SURVIVES FOR TEMPORARY FAULT AND NOT LOSE THE
SECOND ELEMENT AFTER FAULT CLEARING
 LOSES 2ND ELEMENT DUE TO FAULT CLEARING FOR PERMANENT FAULT.
REACHES NEW STEADY STATE W/O LOSING SYNCHRONISM. FOR NEW
STATE, SYSTEM PARAMETERS SHALL NOT EXCEED LOAD LIMITS, BUT
REQUIREMENT OF LOAD SHEDDING/ RESCHEDULING OF GENERATION
FOR BRINGING SYSTEM PARAMETERS WITHIN NORMAL LIMITS
REQUIRED

14. FOR T.S CONNECTING GENERATORS OR GROUP OF GENERATORS
RADIALLY WITH GRID, FOLLOWING CRITERIA:
 SHOULD MEET ‘N-1’ CRITERIA FOR STEADY STATE AS WELL AS
TRANSIENT STATE.
 FOR ‘N-1-1’ ONLY TEMPORARY FAULT IS CONSIDERED FOR RADIAL
SYSTEM.
 IF PERMANENT IN NATURE OR SOME PART OF GRID IS
DISCONNECTED- REST OF THE GRID APPROACHES NEW STEADY
STATE W/O LOSING SYNCHRONISM. IN NEW STATE, SYSTEM SHALL
NOT EXCEED EMERGENCY LIMITS.

16. FOLLOWING POWER SYSTEM STUDIES CAN BE
UNDERTAKEN
 POWER FLOW STUDIES
 SHORT CIRCUIT STUDIES
 STABILITY STUDIES
 EMTP STUDIES

17. 1. CONSIDERATION OF VOLTAGE LEVEL
 FOR PLANNING OF ISTS,
I. THE TRANSMISSION NETWORK MODELLED DOWN TO 220kV. (FOR
N.E REGION, PARTS OF UTTARAKHAND,HIMACHAL PRADESH AND
SIKKIM= 132kV.)
II. GENERATING UNITS WHICH ARE STEPPED UP AT 132kV OR 110kV MAY
BE CONNECTED TO NEAREST 220kV BUS THROUGH 220/132 kV
TRANSFORMER FOR SIMULATION PURPOSES.
III. GENERATING UNITS SMALLER THAN 50MW WITHIN A PLANT LUMPED
AND MODELED AS A SINGLE UNIT, BUT INSTALLED CAPACITY< 200MW.
IV. LOAD MAY BE LUMPED AT 220kV OR 132/110kV
 FOR INTRA-STS, TRANSMISSION NETWORK MODELLED DOWN TO 66kV.
STUs MAY ALSO CONSIDER MODELLING SMALLER UNITS.

18. 2. TIME HORIZONS
 SYSTEM STUDIES FOR FIRMING UP THE TRANSMISSION
PLANS MAY BE CARRIED OUT WITH 3-5 YEARS.
i. ABOUT 3 YEARS FOR AUGMENTATION OF CAPACITORS,
REACTORS,TRANSFORMERS ETC
ii. 4-5 YEARS FOR NEW TRANSMISSION LINES AND
SUBSTATIONS
 PREPARE BASE CASE MODELS CORRESPONDING TO LOAD
GENERATION SCENARIOS FOR 5 YEAR HORIZON.

19. 1. ACTIVE POWER
 SYSTEM PEAK DEMANDS (STATE, REGION, NATIONAL) BASED ON
LATEST ELECRIC POWER SURVEY REPORT OF CEA.
 LOAD DEMANDS AT OTHER PERIODS (SEASONAL VARIATION AND
MIN LOADS) BE DERIVED ON ANNUAL PEAK DEMAND AND PAST
PATTERN
 DURING SIMULATION, IF PEAK LOAD FIGURES ARE MORE THAN
PEAKING AVAILABLE GENERATION, LOADS MAY BE ADJUSTED
SUBSTATION WISE
 DURING SIMULATION, IF PEAKING AVAILABILITY MORE THAN PEAK
LOAD, GENETATION DISPATCHES SUITABLY REDUCED SUCH THAT
INTER REGIONAL POWER TRANSFERS ARE HIGH
 LOAD VARIATIONS OVER YEAR SHALL BE
i. ANNUAL PEAK LOAD
ii. SEASONAL VARIATION IN PK LOADS (SUMMER,WINTER,MONSOON)
iii. SEASONAL LIGHT LOAD
 SUBSTATION WISE ANNUAL LOAD DATA TO BE PROVIDED BY STU.

20. 2. REACTIVE POWER
 STUs MUST PROVIDE SUBSTATION WISE MAX AND
MIN DEMAND IN MW & MVAr ON SEASONAL BASIS
 ELSE, LOAD POWER FACTOR AT 220kV AND 132kV
0.95 LAG (PEAK LOAD)
0.98 LAG (LIGHT LOAD)
 STU TO PROVIDE REACTIVE COMPENSATION TO
BRING POWER FACTOR CLOSE TO UNITY AT 132kV &
220kV.

21. 1. ALL INDIA PEAKING AVAILABILITY CALCULATED AS PER
NORMS
2. FOR NEW TRANSMISSION LINES AND SUBSTATIONS,
PEAK LOAD SCENARIOS FOR SUMMER,WINTER,
MONSOON SEASONS TO BE STUDIED. LIGHT LOAD
SCENARIOS ALSO CARRIED OUT AS PER REQUIREMENTS
3. FOR RENEWABLE ENERGY SOURCE, SOLAR OR WIND
GENERATION INJECTIONS CONSIDERED IN COMBN
WITH CONVENTIONAL METHODS. INTRA-STATE
GENERATING STATION OF R.E.S PURCHASING STATE MAY
BE BACKED DOWN, SO THAT IMPACT OF R.E.S
GENERATION IS MINIMUM

22. 4. SPECIAL AREA DISPATCHES
• THEY CORESPOND TO HIGH AGRICULTURAL LOAD WITH LOW PF
• COMPLETE CLOSURE OF GENERATING STATION NEWAR A MAJOR LOAD
CENTRE
5. FOR THERMAL UNITS (COAL,GAS,DIESEL,NUCLEAR), MIN OUTPUT LEVEL TO
NOT BE TAKEN LESS THAN 70% OF RATED INSTALLED CAPACITY. FOR
RUNNING WITH OIL SUPPORT, UPTO 25%.
6. GENERATING UNIT TO BE MODELLED TO RUN AS PER CAPABILITY CURVE.
FOR ABSENCE OF CURVE, FOLLOWING VALUES.

23. 7. GENERATOR TO PROVIDE TECHNICAL DETAILS LIKE
CAPABILITY CURVE, GENERATOR, EXCITER, GOVERNER,
PSS PARAMETERS, ETC. FOR MODELLING OF THE
MACHINES FOR STEADY STATE AND TRANSIENT STATE
STUDIES.

24. 1. STUDIES TO BE CARRIED OUT IN CLASSICAL METHOD, FAULT
PRE FAULT VOLTAGES AND SUB TRANSIENT REACTANCE OF
SYNCHRONOUS MACHINE
2. MVA OF ALL GENERATING UNIT IN PLANT TO BE
CONSIDERED FOR DETERMINING MAX SC LEVEL AT VARIOUS
BUSES OF SYSTEM
3. INTER WINDING REACTANCES FOR 3 WINDING
TRANSFORMER TO BE CONSIDERED
4. VECTOR GROUP OF TRANSFORMER TO BE CONSIDERED
DURING STUDIES.
5. SC LEVEL FOR 3-Φ TO GROUND AND 1-Φ TO GROUND TO BE
CALCULATED.
6. SC LEVEL MAY BE LOW FOR LIGHT LOAD SCENARIO AS
COMPARED TO PEAK LOAD SCENARIO. LEVEL VARIES WITH
OPERATING CONDITIONS

25.  FOR LARGE INTER CONNECTED GRID, UNPREDICTABLE POWER
FLOWS CAN OCCUR DUE TO IMBALANCE IN LOAD GENERATION
BALANCE IN DIFFERENT PARTS OF GRID. LEADS TO OVERLOADING
OF TRANSMISSION ELEMENT. SUCH SITUATIONS ARE UNAVOIDABLE
AND MARGINS AT PLANNING STAGES ARE REQUIRED.
 OVERLOAD CAPACITY OF TRANSMISSION LINES TO BE CONSIDERED.
 THERMAL LOADING LIMITS FOR LINE AND TRANSFORMER TO BE
10% AND 15% FOR INTER REGIONAL.
 MARGIN OF ±2% KEPT IN VOLTAGE LIMITS FOR ‘N-0’ AND ‘N-1’

26.  ALL TRANSFORMERS CONSIDERED TO BE AT
NOMINAL TAPS. ON LOAD TAP CHANGER (OLTC)
NOT CONSIDERED.
 FOR NUCLEAR GENERATING UNITS.

27.  ARE PERFORMED TO CALCULATE MAGNITUDE AND
PHASE ANGLES OF VOLTAGE, ACTIVE, REACTIVE
POWER FOR GIVEN BUS.
 PLAN THE BEST OPERATION ; HELP IN
ASCERTAINING THE EFFECTS OF NEW
LOADS,GENERATING STATIONS; PLAN THE FUTURE
EXPANSION; ESSENTIAL FOR DESIGNING A NEW
POWER SYSTEM.
 FOUR VARIABLES ASSOCIATED WITH EACH BUS,
P,Q,V AND δ. TWO OF THE FOUR ARE KNOWN;
OTHER TWO UNKNOWN, DEPENDING UPON THE
TYPE OF BUS.

29.  FOR REACTIVE POWER COMPENSATION SHUNT
CAPACITORS, SHUNT REACTORS,STATIC Var
COMPENSATORS, VARIABLE SERIES CAPACITOR,
OTHER FACTS CONTROLLED DEVICES; APPROPRIATE
STUDIES ARE DONE.
SHUNT CAPACITORS
 132/220kV NETWORK SHUNT CAPACITORS FOR
MEETING REACTIVE POWER REQUIREMENTS
PROVIDED AT 132/220kV BUSES FOR SIMULATION.
 LOAD POWER FACTOR CLOSE TO UNITY BY
PROVIDING SHUNT CAPACITORS.
 400/220kV OR 400/132kV OR 220/132kV (OR 66 Kv)
REACTIVE POWER FLOW IS MININMUM.

30. STATIC Var COMPENSATION
 SVC PROVIDED TO DAMP POWER SWINGS AND PROVIDE
SYSTEM STABILITY UNDER ‘N-0’, ’N-1’, ’N-1-1’ CONDITIONS
SHUNT REACTORS
 SIZE OF REACTORS SHOULD BE SUCH THAT UNDER
STEADY STATE, SWITCHING ON AND OFF OF THE
REACTOR SHALL NOT CAUSE A VOLTAGE CHANGE
EXCEEDING 5%.
STANDARD SIZE (MVAr) OF REACTORS

31.  FIXED LINE REACTORS TO CONTROL POWER
FREQUENCY TEMPORARY OVER VOLTAGE AFTER
VOLTAGE REGULATION HAS TAKEN PLACE
 LINE REACTORS (SWITCHABLE/CONTROLLED/FIXED)
PROVIDED IF CHARGING EHV LINE IS NOT POSSIBLE
WITHOUT EXCEEDING MAX VOLTAGE LIMITS.

32.  FOR EHV SUBSTATIONS REQUIREMENTS TOTAL LOAD CATERED BY
SUBSTATION OF A PARTICULAR VOLTAGE LEVEL, MVA CAPACITY, NUMBER OF
FEEDERS.
 IMPORTANT BECAUSE PROVIDES THE NUMBER OF SUBSTATIONS REQUIRED
FOR MEETING A PARTICLUAR QUANTUM OF LOAD
 FOLLOWING CRITERIS PRESENT FOR DESIGNING EHV SUBSTATION.
1. MAX SC LEVEL ON ANY BUS NOT TO EXCEED 80% OF RATED SC CAPACITY.
SPLITTING OF BUS, SERIES REACTOR ETC TECHNOLOGIES MAY BE
ADOPTED TO LIMIT SC CURRENT.
BREAKING CURRENT CAPACITY OF SWITCHGEAR AT DIFFERENT VOLTAGE
LEVELS

33. 2. RATING OF EQUIPMENT SHAL BE SUCH THAT DO NOT LIMIT
LOADING LIMITS OF SUBSTATION.
3. WHEN MAX CAPACITY OF A SUBSTASTION IS REACHED,
EFFORT TO BE MADE TO CREATE NEW SUBSTATION RATHER
THAN ADD TRANSFORMER CAPACITY.
4. WHILE INCREASING TRANSFORMER CAPACITY, FAULT LEVEL
SHOULD BE KEPT IN CHECK
5. SIZE AND NO. OF ICTs PLANNED IN SUCH A WAY THAT
OUTAGE OF ONE UNIT WOULDN’T OVERLOAD OTHER ICTs.
6. STUCK BREAKER CONDITION SHALL NOT CAUSE DISRUPTION
OF MORE THAN 4 FEEDERS FOR 220kV SYSTEM AND TWO
FOR 400 AND 765kV SYSTEM.

34.  CAPACITY FACTOR RATIO OF MAX GENERATION
AVAILABLE AT AN AGGREGATION PT. TO THE ALGEBRAIC
SUM OF EACH WIND MACHINE/SOLAR PANEL
CONNECTED TO THAT GRID POINT.
 THERMAL LINE LOADING LIMIT OF LINES CONNECTED TO
WIND MACHINE TO BE CONSIDERED AT MAX 12KM/H
SPEED.
 POWER FACTOR FOR WIND AND SOLAR PLANTS 0.98

35.  CONSIDER TWO INDEPENDENT SOURCES OF POWER
SUPPLY FOR PROVIDING START UP POWER.
 ANGLE BETWEEN START UP POWER SOURCE AND
GENERATION SWITCHYARD SHOULD BE MAX 10°.
 EVACUATION SYSTEM FOR NUCLEAR POWER
STATIONS BE PLANNED TO TERMINATE IT AT LARGE
LOAD TO FACILITATE ISLANDING OF POWER SYSTEM
DURING CONTINGENCY

36.  HVDC BIPOLE CONSIDERED FOR TRANSMITING BULK
POWER (>200 MW) OVER LONG DISTANCE MORE
THAN 700KM.
 ALSO USED IN TRANSMISSION CORRIDORS THAT
HAVE AC LINES CARRYING HEAVY POWER FLOWS
(MORE THAN 5000MW) TO CONTROL AND
SUPPLEMENT THE AC TRANSMISSION NETWORK.
 RATIO OF FAULT LEVEL (IN MVA) AT ANY CPNVERTER
STATION (FOR CONVENTIONAL SOURCE) TO POWER
FLOW ON HVDC BIPOLE SHOULD NOT BE LESS THAN
3 UNDER ANY GIVEN SCENARIO.

37.  VOLTAGE STABILITY STUDIES TO BE CARRIED BY
CREATING FICTITIOUS SYNCHRONOUS CONDENSER AT
CRITICAL BUSES USING LOAD FLOW ANALYSIS PROGRAM.
BUS IS CONVERTED TO PV BUS IN THIS.
 MVAr ABSORPTION DOES NOT INCREASE BY REDUCING
VOLTAGE IT MAY ALSO BE REDUCED TOO. I.E MVAr
ABSORPTION DOES NOT INCREASE FURTHER. THIS POINT
CAN BE CALLED KNEE POINT OF Q-V CURVE. REPRESENTS
POINT OF VOLTAGE INSTABILITY
 FROM THE GRAPH, DISTANCE BETWEEN KNEE POINT
AND ZERO MVAr VERTICAL AXIS. IS AN INDICATOR OF
PROXIMITY TO VOLTAGE COLLAPSE.
 EACH BUS TO OPERATE ABOVE KNEE POINT OF Q-V
CURVE UNDER ALL CONDITIONS.

38.  FOR ZONE-3 RELAY, VALUE OF RELAY SETTING TO BE
SUCH THAT IT DOES NOT TRIP AT EXTREME
LOADING. HENCE TAKEN AS 120% OF THERMAL
CURRENT LOADING LIMIT AND 0.9 PU VOLTAGE.
 ELSE OTHER MEASURES ARE UNDERTAKEN AND
VOLTAGE TO BE TAKEN AS 0.95 PU.