Integrated Power System
Spreads over thousands of square kilometers
Hundreds of Generating Units
Thousands of Circuit Kilometers of Lines
Tens of Thousands of Devices
SINGLE LARGEST COMPLEX MACHINE
100% Reliability IMPOSSIBLE
NORMAL
RESTORATIVE
A L E R T
EMERGENCY
RESTORATION OBJECTIVES
RESTORING NORMAL SYSTEM
OPERATION AS QUICKLY AS POSSIBLE
SYNCHRONISING OF AT LEAST ONE UNIT
AT ALL POWER STATION
RESTORING ESSENTIAL LOADS
ESTABLISHING ALL INTERCONNECTIONS
STARTING ECONOMIC DISPATCH
STARTING ALLOCATION OF C. S SHARE
MINIMIZING AMOUNT OF UNSERVED
ENERGY
RESTORATION PROBLEMS
IMPAIRED COMMUNICATIONS, LIMITED
INFORMATION.
RE-ASSEMBLING TIE ELEMENTS OF
POWER SYSTEM.
UNFAMILIARITY WITH THE SITUATION
(DOES NOT OCCUR REGULARLY)
TIME CONSTRAINTS
INFORMATION TO BE FURNISHED TO
AUTHORITIES- PRESSURE ON OPERATOR
SYSTEM STATUS DETERMINATION
EXTENT OF BLACK OUT AND ACTUAL REQUIREMENT
IDENTIFICATION OF BOUNDARIES OF ENERGISED AREAS
ASCERTAINING FREQUENCY & VOLTAGE OF ENERGISED
AREA
STATUS OF GENERATING PLANTS(HOT/COLD/HOUSELOAD )
NON AVAILABILITY OF ELEMENTS(LC/FAULT ETC)
OVERLOADING OF ELEMENTS
LOADS INTERRUPTED BY UNDER- FREQUENCY RELAY
OPERATION OR DIRECT TRIPPING
STATUS OF BREAKERS
PLANT SURVIVAL AND START UP
 CONSIDERATION OF TIME-CRITICAL BOILERTURBINE START-UP CHARACTERISTICS (FOR
PREDOMINANTLY THERMAL SYSTEMS)
 SURVIVAL POWER SUPPLY TO THE PLANTS AT
THE EARLIEST WITH AVAILABLE ARRANGEMENT
(DG SETS) FOR
Turbine emergency oil pump
. Jacking oil pumps
. Barring gear of the turbine
. Lubricating oil pumps
. Emergency lighting
. Battery charger
Compressor for CB
THUMB
RULES
PLANT SURVIVAL AND START UP
ALL DG/GT’S TO RUN TO PROVIDE START UP
POWER.
ESTIMATION OF TOTAL START UP POWER
REQUIRED TO RUN AT LEAST ONE MACHINE OF EACH
POWER STATIONS.
TAKING CARE NOT TO LOAD THE GENERATOR
SUPPLYING START-UP POWER BEYOND 80% OF ITS
CAPACITY.
RELEASING AUXILIARY POWER IN STEPS.
THE CAPACITY (I.E. FAULT LEVEL) OF ISLAND
(SUPPLYING
START UP
POWER) TO SUSTAINSTARTING CURRENT 0F BFP ETC. TO BE CHECKED.
NETWORK
PREPARATION
CLEARING ALL DE-ENERGISED BUSES
GLOBAL OPENING OF ALL THE BREAKERS
ELSE:-SELECTIVE BREAKER
CAREFUL CONSIDERATION
OPERATION
AFTER
SECTIONALISING A SYSTEM INTO SUB-SYSTEMS TO
ENABLE PARALLEL RESTORATION OF ISLANDS
AUTOMATICALLY SWITCHED CAPACITORS AND
UNDER FREQUENCY RELAYS MAY HAVE TO BE KEPT
OUT OF SERVICE AT THE INITIAL STAGE
NETWORK ENERGISATION
• IDENTIFY THE IMPORTANT AND
ESSENTIAL LOADS TO BE RESTORED FIRST
• AT EVERY STAGE WE SHOULD BE ABLE TO
SATISFY
– REACTIVE POWER BALANCE
– LOAD GENERATION BALANCE
– PROTECTION AND PLANT CONTROL SYSTEM
REQUIREMENTS
• HVDC IMPORT – ONLY WHEN MIN FAULT
LEVEL IS AVAILABLE.
• AVOID PARALLELING ISLANDS THROUGH
WEAK LINKS
THUMB
RULES
NETWORK ENERGISATION
PLANT CONTROL SYSTEM CHARACTERISTICS
A) MECHANICAL CONSIDERATIONS
REGULATION OF RATE OF CHANGE OF TEMPERATURE TO BE
KEPT MANUAL
CONTROL FEED WATER WITH THE SOLE OBJECTIVE OF
MAINTAINING DRUM LEVEL AT SET POINT
PLANTS HAVING FEED WATER REGULATING VALVES
PREFERABLE TO THOSE HAVING TURBINE-DRIVEN FEED PUMPS
TWO FUEL SUPPLY SYSTEMS - ONE (OR NONE) AUTOMATIC AND
ONE (OR BOTH) IN MANUAL.
NETWORK ENERGISATION
B) ELECTRICAL CONSIDERATIONS
VOLTAGE REGULATOR TO BE SWITCHED TO
AUTOMATIC CONTROL (FROM MANUAL) ONLY WHEN
THE UNIT REACHES A MIN. OPERATING POINT AND A
SUFFICIENT VAR GENERATION 1S ESTABLISHED
PROTECTIVE RELAYS SUCH AS VOLTS PER HZ,
OUT
OF
STEP,
UNDER
EXCITATION,
DISTANCE,
FREQUENCY & FIELD. FORCING CAN INITIATE AN
UNDESIRABLE
REGULATOR
RESPONSE
GENERATOR TRIP DURING START UP
OR
NETWORK ENERGISATION
STRUCTURAL
SYSTEM SIZE
METROPOLITAN OR RURAL
COMPACT OR EXTENSIVE GENERATION
TRANSMISSION VOLTAGE LEVELS
TYPES AND SIZES OF LOAD BLOCKS
AVAILABILITY OF INTERCONNECTION
ASSISTANCE
NETWORK ENERGISATION
DYNAMICS
REACTIVE CAPABILITIES OF GENERATORS
/SYNCHRONOUS CONDENSERS
UNDER
NORMAL
AND
EMERGENCY
OPERATING
CONDITIONS.
SHUNT REACTOR AND CAPACITOR
LOCATIONS AND MODES OF CONTROL.
SIZES,
CHARGING
CURRENTS
AND
MAXIMUM
SUSTAINABLE OVERVOLTAGE, TRANSFORMER
REACTANCES, TAP RANGES AND MODES OF
CONTROL
GENERATOR
MAXIMUM
AND
MINIMUM
OUTPUTS UNDER DIFFERENT CONDITIONS
NETWORK ENERGISATION
REACTIVE POWER BALANCE
SOURCE
GENERATION
ABSORPTION
GENERATOR
YES
YES
LINE CHARGING
YES
SHUNT CAPACITOR
YES
SHUNT REACTOR
YES
SYN CONDENSOR
YES
YES
STATIC VAR
COMPENSATOR
YES
YES
THUMB RULES
NETWORK ENERGISATION
LOAD GENERATION BALANCE
• TYPE OF THE LOAD
– PEAK OR OFF PEAK
– COLD LOAD INRUSH
•
•
•
•
GENERATOR CAPACITY
MINIMUM LOADING OF GENERATOR
RESPONSE TO SUDDEN LOAD PICKUP
TIME ELAPSED(HOT START)
LOAD RESTORATION
• DURING RESTORATION EFFECT OF EACH
RESTORATION ACTION ON FOLLOWING TO
BE CONSIDERED
–
–
–
–
–
–
GENERATOR LOADING
TRANSMISSION LINE LOADING
LOAD ANGLE
RATE OF LOADING
RESPONSE OF THE GEN TO LOAD CHANGE
CHANGE IN SYSTEM FREQ AND OPERATION OF
UFR’S
– FLUCTUATING LOADS- EX. TRACTION,
FURNACE ETC.
THUMB
RULES
RESTORATION STRATEGIES
BUILD DOWN
OR
SEQUENTIAL
STRATEGY
BUILD UP
OR
PARALLEL
STRATEGY
BUILD DOWN OR SEQUENTIAL STRATEGY
RE-ENERGIZATION OF BULK POWER NETWORK
BALANCED STEP-BY-STEP RESTORATION OF LOADS AND
GENERATION
SUITABLE FOR
SMALL SYSTEMS NOT HAVING LONG EHV LINES
OR PREDOMINANTLY HYDRO SYSTEMS WITH HIGH REACTIVE
ABSORPTION CAPABILITY
OR FOR LARGE SYSTEMS WITH VERY COMPACT SERVICE
TERRITORIES
USUALLY SELECTED WHEN STRONG NEIGHBOURING
INTERCONNECTION ASSISTANCE 1S AVAILABLE
INTERCONNECTION STATUS IS TO BE ASSESSED, HENCE TIME
CONSUMING AND TASKING.
BUILD UP STRATEGY
 SIMULTANEOUS RESTORATION OF ISLANDS/
SUBSYSTEMS FOLLOWED BY THEIR MUTUAL
SYNCHRONIZATION
 USUALLY SELECTED IN CASE OF A COMPLETE
SYSTEM COLLAPSE AND LACK OF INTERCONNECTION
ASSISTANCE
 RELATIVELY QUICK PROCESS
 REQUIRES SEVERAL OPERATING TEAMS AND
ADEQUATE COMMUNICATION FACILITIES FOR MUTUAL
COORDINATION
BUILD UP EXAMPLE- AP SYSTEM RESTORATION
NSR+SSLM
VTS+GAS
RyTPP+
CUDDAPAH
RADIAL ON TN
SPECIAL CONSIDERATIONS
FIRM TRANSMISSION IN THE INTERCONNECTION BETWEEN SUBSYSTEMS
AND FIRM GENERATION CAPACITY IN EACH SUB SYSTEM TO BE ENSURED
DURING EARLY STAGES OF RESTORATION
DEACTIVATION OF AUTOMATIC LOAD SHEDDING
SWITCHED CAPACITORS DURING INITIAL STAGES,
AND AUTOMATIC
RESTORATION OF SMALLER RADIAL LOADS FOLLOWED BY LOW VOLTAGE
AC NETWORK LOADS WHILE MAINTAINING REASONABLY CONSTANT REAL TO
REACTIVE POWER RATIO
PICKING UP SMALL BLOCKS OF LOADS FOLLOWED BY AS LARGE AS
POSSIBLE, WITHOUT RISKING DANGEROUS DECLINE OF FREQUENCY, AS
RESTORATION PROCEEDS.
KEEPING GENERATOR TERMINAL VOLTAGES RELATIVELY LOW INITIALLY,
AND ADJUSTING TRANSFORMER TAPS, SUBSEQUENTLY AS RESTORATION
PROCEEDS
RESTORATION PLANNING
GENERAL GUIDELINES
FORMATION OF A PLANNING TEAM
•
PARTICIPATION OF EXPERIENCED/KNOWLEDGEABLE
PERSONNEL FROM RESPECTIVE FIELDS LIKE
PROTECTION,
COMMUNICATION, OPERATIONS,
SYSTEM ANALYSIS ETC.
•
REVIEW OF SYSTEM CHARACTERISTICS (RELEVANT
TO RESTORATION)
RESTORATION PLANNING
COMMON CONCERNS
• TIME CONSUMING NATURE OF SWITCHING
OPERATION
• START-UP TIMINGS OF THERMAL UNITS
• FREQUENCY RESPONSE OF PRIME MOVERS TO
SUDDEN LOAD PICK UP
• COLD LOAD INRUSH, POWER FACTORS AND
COINCIDENT DEMAND FACTORS
• AVAILABILITY OF GOVERNOR FACILITIES OF UNITS
FORMULATION OF ASSUMPTIONS
WORST POSSIBLE SCENARIO TO BE CONSIDERED USING
SYSTEM OPERATORS EXPERIENCE AND JUDGEMENT
CONSTRAINTS MAY DIFFER WIDELY FOR PEAK AND LEAN
CONDITIONS
COORDINATION OF LOAD PICKUP WITH GENERATOR
RESPONSE AND ARRESTING FALL OF FRFQUFNCY, BEYOND
PRIME MOVER RECOVERY CAPABILITY UNDER PEAK
CONDITION
BLACK-START FACILITIES MAY NOT BE AVAILABLE DURING
WEEK END LEAN PERIOD
ESTABLISHMENT OF GOALS
LOCAL CONDITIONS LIKE GENERATIOR MIX TYPE OF LOAD AND
CONTRACTUAL OBLIGATIONS PLAY A DECISIVE ROLE
IMMEDIATE OBJECTIVE (SYSTEM SPECIFIC) COULD BE.
RE-ENERGIZING THE BULK POWER NETWORK
OR ATTAINING A CERTAIN
LEVEL OF ACTIVE AND REACTIVE
CAPABILITY
OR PICKING UP A DOWNTOWN LOAD
OR SUPPLYING TIME-CRITICAL INDUSTRIAL LOADS
OR ENERGIZING EHV LINE TO A REMOTE, LARGE GENERATING
STATION
VALIDATION OF ASSUMPTIONS
•
PROPER MODELLING OF STEADY STATE AND DYNAMIC BEHAVIOUR OF
POWER SYSTEM
•
CONFIRMING THE FEASIBILITY AND SECURITY OF PROPOSED ACTIONS
USING A VARIETY OF ANALYSIS AND SIIMULATION TOOLS LIKE STEADYSTATE POWER FLOW, TRANSIENT AND DYNAMIC STABILITY ANALYSIS AND
ELECTROMAGNETIC TRANSIENT SIMULATIONS
•
LOAD DATA, GENERATION DATA ETC. TO BE PREPARED CAREFULLY
ITERATION
TWO ITERATIONS ARE INVOLVED 1.
MODELS HAVE TO BE VALIDATED AGAINST MEASURED AND TELEMETERED
DATA
2.
THE RESTORATION PLAN (TACTICS) DEVELOPED TO BE CHECKED AGAINST
THE INITIAL STRATEGY FOR CONFORMITY AND FEASIBILITY
LOGISTICS AND COMMUNICATION
CLOSE AND CONTINUAL CO-ORDINATION AMONG POWER
SYSTEM POWER PLANT AND FIELD
NEIGHBOURING
INFORMED
OF
TO
UTILITIES,
OPERATORS
AUTHORITIES
TIME TO TIME ABOUT THE
TO
BE
PROGRESS
RESTORATION.
DEPEND
MORE
ON
THE
UTILITIES’
OWN
COMMUNICATION FACILITIES
FALL
BACK
ARRANGEMENT
COMMUNICATION FAILURE.
IN
CASE
OF
EXPERT / COMMANDO GROUP
COMMANDO GROUP TO BE
FORMED
AS
THE
SYSTEM COMPLEXITY GROWS.
GROUP SHOULD CONSIST OF ENGINEERS FROM
DIFFERENT
FIELDS
AND
BELONGING
TO
DIFFERENT UTIILITIES.
PERFECT UNDERSTANDING IN THIS CORE
GROUP
IT ENCHANCES THE MORAL STRENGTH OF FIELD
OFFICERS AS WELL AS REDUCES RESTORATION
TIME
AUIDITS AND UPDATES
A TECHNICAL PERSON OUTSIDE THE RESTORATION
TEAM SHOULD AUDIT THE ACTIVITIES.
AUDITED RESTORATION PLAN MUST BE UPDATED.
DOCUMENTS
MUST BE REVISED
REGULARLY TO
REFLECT THE LATEST CHARACTERISTICS OF THE
SYSTEM.
CHANGES IN THE SCADA/EMS
INSTALLATION OR
MAJOR PLANT CONTROL, AVAILABLE TOOLS ALSO TO
BE INCORPORATED.
TRAINING
INSTRUCTION MANUALS OR AUDIO –VISUAL TAPES, FOR
INDEPENDENT STUDY
CLASSROOM INSTRUCTIONS
LEARNING FROM PAST EXPERIENCE DURING RESTORATION.
OPERATOR TRAINING SIMULATOR.
ROLE PLAY
OPERATOR’ S PROBLEM SOLVING CAPABILITY CAN ALSO
BE EXPLORED AND DEVELOPED.
ALTERNATIVE, SOURCE OF FINDING NEW IDEAS.
DETAILED INTERACTION WITH THE PERSONS INVOLVED IN
RESTORATION
DOCUMENTATION
PURPOSE: TRAINING- REFERENCE, IMPROVEMENT OF
RESTORATION PROCEDURES.
SHOULD BE READILY ACCESSIBLE AND EASILY
UNDERSTOOD.
SHOULD BE STORED IN A CONVENIENT MEDIA FOR
QUICK PROCESSING.
SHOULD BE ILLUSTRATED WITH FAMILIAR DIAGRAMS
AND CHARTS
ACTIONS REJECTED AND INCORPORATED IN THE
PLAN MUST BE RECORDED