INTELLIGENT INTELLIGENT LOAD SHEDDINGLOAD SHEDDING

PRESENTED BY PRESENTED BY

SUGANDHA SHARMASUGANDHA SHARMA

WHAT IS LOAD SHEDDINGWHAT IS LOAD SHEDDING

Excess of load over available generation Excess of load over available generation

Drop in frequency Drop in frequency

Casacading effectCasacading effect

To avoid this, some load is shedTo avoid this, some load is shed

CONCEPT OF CONCEPT OF LOADSHEDDINGLOADSHEDDING

Excitation / Generator – Reactive Excitation / Generator – Reactive Power – VoltagePower – Voltage

Drainage of reactive powerDrainage of reactive power Call its over excitation capibility Call its over excitation capibility Prime Mover / Generator – Real Prime Mover / Generator – Real

Power - FrequencyPower - Frequency Frequency drainageFrequency drainage Stored energy variesStored energy varies

TYPE OF ACTION REQUIREDTYPE OF ACTION REQUIRED

Require fast responseRequire fast response Longer delays,require more load to be shedLonger delays,require more load to be shed Generation control cannot act fast enoughGeneration control cannot act fast enough Disturbance type and locationDisturbance type and location System response different depending on System response different depending on

location of disturbancelocation of disturbance Different load shedding strategyDifferent load shedding strategy Normal and abnormal operating conditionsNormal and abnormal operating conditions

CONVENTIONAL CONVENTIONAL TECHNIQUESTECHNIQUES

BREAKER INTERLOCK SCHEMEBREAKER INTERLOCK SCHEME

UNDER FREQUENCY RELAY SCHEMEUNDER FREQUENCY RELAY SCHEME

PLC BASED LOAD SHEDDINGPLC BASED LOAD SHEDDING

BREAKER INTERLOCK BREAKER INTERLOCK SCHEMESCHEME

DISADVANTAGESDISADVANTAGES

Difficult to change load priority Difficult to change load priority

Only one stage of load shedding is Only one stage of load shedding is availableavailable

More loads are shed than necessary More loads are shed than necessary

UNDER FREQUENCY RELAY UNDER FREQUENCY RELAY SCHEME SCHEME

DISADVANTAGESDISADVANTAGES Slow response time of frequency relaysSlow response time of frequency relays

Incorrect Load may be Dropped Causing Incorrect Load may be Dropped Causing Undesirable BlackoutsUndesirable Blackouts

Analysis knowledge is lostAnalysis knowledge is lost

PLC BASED LOAD PLC BASED LOAD SHEDDINGSHEDDING

circuit breaker tripping programmedcircuit breaker tripping programmed

Modification of the logic requires changing Modification of the logic requires changing programmed logicprogrammed logic

ADVANTAGE: access to actual operating status of ADVANTAGE: access to actual operating status of the power systemthe power system

DISADVANTAGE: pre-defined load priority tables DISADVANTAGE: pre-defined load priority tables in the PLC in the PLC

“ “load shedding system uses load shedding system uses real time system-wide data real time system-wide data acquisition that continually acquisition that continually updates a computer based updates a computer based real-time system model”real-time system model”

BLOCK DIAGRAM OF ILSBLOCK DIAGRAM OF ILS

COMPONENTS OF ILSCOMPONENTS OF ILS

LOAD PRESERVATIONLOAD PRESERVATION

LOAD RESTORATIONLOAD RESTORATION

LOAD SHEDDING VALIDATIONLOAD SHEDDING VALIDATION

LOAD PRESERVATIONLOAD PRESERVATION

Calculates minimum Calculates minimum required power to be required power to be shedshed

Selects optimal Selects optimal combination of loads combination of loads

Different load Different load priority tables, load priority tables, load groups, options, groups, options, calculation method calculation method etc.etc.

LOAD RESTORATIONLOAD RESTORATION

Available spinning Available spinning reservereserve

Starting voltagesStarting voltages Operating voltagesOperating voltages User-defined logicUser-defined logic Alternate source Alternate source

detectiondetection System configuration System configuration

statusstatus system frequencysystem frequency interlock and switching interlock and switching

sequence logicssequence logics

LOAD SHEDDING LOAD SHEDDING VALIDATIONVALIDATION

IMPLEMENTATION CONFIGURATION OF IMPLEMENTATION CONFIGURATION OF ILSILS

SOFTWARE IMPLEMENTATION SOFTWARE IMPLEMENTATION OF ILSOF ILS

SOFTWARE IMPLEMENTATION SOFTWARE IMPLEMENTATION OF ILSOF ILS

SOFTWARE IMPLEMENTATION SOFTWARE IMPLEMENTATION OF ILSOF ILS

SOFTWARE IMPLEMENTATION SOFTWARE IMPLEMENTATION OF ILSOF ILS

SOFTWARE IMPLEMENTATION SOFTWARE IMPLEMENTATION OF ILSOF ILS

SOFTWARE IMPLEMENTATION SOFTWARE IMPLEMENTATION OF ILSOF ILS

SOFTWARE IMPLEMENTATION SOFTWARE IMPLEMENTATION OF ILSOF ILS

SOFTWARE IMPLEMENTATION SOFTWARE IMPLEMENTATION OF ILSOF ILS

SOFTWARE IMPLEMENTATION SOFTWARE IMPLEMENTATION OF ILSOF ILS

KEY FETURES OF ILSKEY FETURES OF ILS

Hardware independent Hardware independent Supports large number of protocols and standardsSupports large number of protocols and standards User-defined load priority User-defined load priority User defined load groupsUser defined load groups Unlimited load shedding schedulesUnlimited load shedding schedules Operator friendly interfaceOperator friendly interface On-line testing to validate ILS actionsOn-line testing to validate ILS actions Load restorationLoad restoration Eliminate unnecessary load shedding Eliminate unnecessary load shedding Reduction of downtime for critical loads Reduction of downtime for critical loads Reduction of spinning reserve requirements Reduction of spinning reserve requirements Reliable load preservation system Reliable load preservation system Fast response to electrical & mechanical disturbances Fast response to electrical & mechanical disturbances Robust calculation method Robust calculation method Operator alerts for marginal operating conditions Operator alerts for marginal operating conditions ReliableReliable

COMPARISON OF ILS WITH COMPARISON OF ILS WITH OTHER TECHINQUESOTHER TECHINQUES

APPLICABLE SYSTEMSAPPLICABLE SYSTEMS

Oil and chemical refineriesOil and chemical refineries Oil production fieldsOil production fields Oil platformsOil platforms MiningMining Cement and paper facilitiesCement and paper facilities Manufacturing plantsManufacturing plants Generation plantsGeneration plants Distribution systemDistribution system

REFERENCESREFERENCES

Edward Kimbark, Power System Stability, Wiley-IEEE, Edward Kimbark, Power System Stability, Wiley-IEEE, February 1, 1995.February 1, 1995.

Warren C. New, Load Shedding, Load Restoration Warren C. New, Load Shedding, Load Restoration and Generator Protection using Solid State and Generator Protection using Solid State andElectromechanical Underfrequency Relays, andElectromechanical Underfrequency Relays, GeneralElectric.GeneralElectric.

Tom Wilson, PLC Based Substation Automation Tom Wilson, PLC Based Substation Automation andSCADA Systems; Selecting a Control andSCADA Systems; Selecting a Control SystemIntegrator, Western Electric Power Institute, SystemIntegrator, Western Electric Power Institute, March 1999.March 1999.

Kevin Warwick, Arthur O., Ekwue and Raj Kevin Warwick, Arthur O., Ekwue and Raj Aggarwal,Artificial Intelligence Techniques in Power Aggarwal,Artificial Intelligence Techniques in Power SystemsSystems

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