Integrated Power SystemIntegrated Power SystemSpreads over thousands of square kilometers Spreads over thousands of square kilometers

Hundreds of Generating UnitsHundreds of Generating Units

Thousands of Circuit Kilometers of LinesThousands of Circuit Kilometers of Lines

Tens of Thousands of DevicesTens of Thousands of Devices

SINGLE LARGEST COMPLEX MACHINESINGLE LARGEST COMPLEX MACHINE

100% Reliability IMPOSSIBLE100% Reliability IMPOSSIBLE

NORMAL

A L E R T

EMERGENCY

RESTORATIVE

  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 OBJECTIVES

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

RESTORATION PROBLEMS

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

SYSTEM STATUS DETERMINATION

CONSIDERATION OF TIME-CRITICAL BOILER- TURBINE 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

PLANT SURVIVAL AND START UP

THUMB RULES

THUMB RULES

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 SUSTAIN- STARTING CURRENT 0F BFP ETC. TO BE CHECKED.

PLANT SURVIVAL AND START UP

CLEARING ALL DE-ENERGISED BUSES

GLOBAL OPENING OF ALL THE BREAKERS

ELSE:-SELECTIVE BREAKER OPERATION AFTER CAREFUL CONSIDERATION

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 PREPARATION

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

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 OR

GENERATOR TRIP DURING START UP

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 SIZES, LOCATIONS AND MODES OF CONTROL.

CHARGING CURRENTS AND MAXIMUM SUSTAINABLE OVERVOLTAGE, TRANSFORMER REACTANCES, TAP RANGES AND MODES OF CONTROL

GENERATOR MAXIMUM AND MINIMUM OUTPUTS UNDER DIFFERENT CONDITIONS

REACTIVE POWER BALANCESOURCE GENERATION ABSORPTION

GENERATOR YES YES

LINE CHARGING YES

SHUNT CAPACITOR YES

SHUNT REACTOR YES

SYN CONDENSOR YES YES

STATIC VAR COMPENSATOR

YES YES

NETWORK ENERGISATION

THUMB RULESTHUMB RULES

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)

NETWORK ENERGISATION

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

THUMB RULES

RESTORATION STRATEGIES

BUILD DOWN OR

SEQUENTIAL STRATEGY

BUILD UP OR

PARALLEL 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 DOWN OR SEQUENTIAL 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 STRATEGY

BUILD UP EXAMPLE- AP SYSTEM RESTORATION

VTS+GAS

NSR+SSLM

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 AND AUTOMATIC SWITCHED CAPACITORS DURING INITIAL STAGES,

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 TEAMFORMATION 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 STEADY-

STATE 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 OPERATORS

NEIGHBOURING UTILITIES, AUTHORITIES TO BE

INFORMED TIME TO TIME ABOUT THE PROGRESS OF

RESTORATION.

TO DEPEND MORE ON THE UTILITIES’ OWN

COMMUNICATION FACILITIES

FALL BACK ARRANGEMENT IN CASE OF

COMMUNICATION FAILURE.

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