Inteligent Load ils

8/14/2019 Inteligent Load ils

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INTELIGENT LOADSHEDDING(ILS)A N E F F E C T IV E A P P R O A C H T O LO A D

S H E D D IN G


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INTRODUCTION

Load shedding is a process in whicha suitable amount load is thrownoff in order to maintain system

stability during over loadedcondition

Generation- load unbalance problems

Load shedding in industrial units


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Problems of frequency decay

Frequency is propotional to speed

Gas turbines are sensitive to frequency

Low frequency problem with thermal

power plants Frequency decay affects quality of

industrial products

Frequency below 49.5Hz make s/munstable

Is load shedding necessary


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Breaker interlock loadshedding

Load sheddingbased on hard-wire signal

&circuit-breakers Fast load shedding

Load sheddingbased on worstcase scenario

Only one stageload shedding

Excessive loadshedding

Modificationcostlier


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Under frequency relay loadshedding

Used to drop loadautomatically inaccordance withthe pre

determinedschedule

Fixed load reductionat fixed frequencylevel

Upon reaching theset point &pre-specified timedelay the relaytrips load breakers

Cycle repeats until

Slow responsetime

Incorrect orexcessive loadshedding

Analysis knowledgeis lost


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PLC based load shedding

Load sheddingbased on Loadvsnum ofgeneratoronline orunder frequencydetection

Shed a preset

sequence ofload

Use of distributedn/w via power

managements/m

Monitoring ofpower s/m islimited to portionof n/w

s/m wide operatingcondition ismissing fromdecision makingprocess result inincorrect loadshedding

Priority load list


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INTELLIGENT LOADSHEDDING

Requirements of ILS s/m1.Pre-disturbance operating conditions

2.post-disturbance operatingconditions3.Nature and duration of disturbance

4.s/m transient response to adisturbance


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ILS block diagram


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Functions of blocks

Knowledgebase-possess s/m dynamicbehavior

Advanced Monitoring

Network Models Trigger List

Load Shed Optimizer- computes optimal

load shedding tables corresponding to system

changes.

Distributed Controls -utilize PLCs to

rapidly execute the load shedding


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, W ith th e a rch ite ctu re d e scrib e d a b o v e a nILS

sch e m e p ro v id e s th e fo llo w in g b e n e fits:

- ,Tim e v a ria n t lo a d sh e d d in g ta b le s w h ichre fle ct

,tru e sta tu s a n d lo a d in g co n d itio n s fo r th e

.sh e d d a b le lo a d s

O p tim a l co m b in a tio n o f sh e d d a b le lo a d s to.m a x im ize lo a d p re se rv a tio n

(Fa st re sp o n se to d istu rb a n ce trig g e rs le ssthan

).1 0 0 m s in m o st case s


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O n e lin e d ia g ra m o f o il re fin e ry


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T h e in te rn a l e le ctrica l n e tw o rk su p p lie s a to ta llo a d

,o f a b o u t 4 5 M W a n d is con stitu te d b y th e:fo llo w in g

S u b sta tio n in te rco n n e ctin g th e in te rn a le le ctrica l

, -syste m to th e p o w er g rid b y tw o th re e w in d in g. / . ,tra n sfo rm e rs 3 4 5 1 3 8 kV ra te d a t 2 0 M V A

.su p p ly in g th re e m a in sw itch b o a rd s

In te rn a l d istrib u tio n syste m o p e ra tin g a t 6 0h e rtz

,o rg a n ize d in to m a in d istrib u tio n sw itch b o a rd s. . ,ra te d a t 1 3 8 kV a n d 4 1 6 kV w h ich su p p lies

/la rg e M V m o to rs a n d o r d istrib u tio n fe e d e rs a sw e ll a s se ve ra l lo w v o lta g e d istrib u tio n

.sw itch b o a rd s To ta lg e n e ra tio n o f 1 5 M W o b ta in e d fro m o n e

( ).g en erator G en set C T h e p la n t is n o rm a lly im p o rtin g 2 3 M W fro m th e


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H a rd w a re co n fig u ra tio n o f P LC/b a se d S m


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TABLE ISHEDDABLE LOAD PRIORITY LIST

Load ShedPriority Load ID

MW Shed- ( )1 Aux B Pump

.1 20( % )MCC24AB 30 Load

.2 55( )Aux A Pump

.2 00( % )MCC24AB 30 Load

.2 55#Desalter 1

.4 25#2 Distillation Unit 1

.3 40#Distillation Unit 3

.2 55#Desalter 2

.4 25( % )3 MCC24AB 40 Load

.4 25#Distillation Unit 5

.2 55 Total Load Shed

.29 55

Frequency response


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ILS communication architecture


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TABLE IILOADS SHED BY ILS SCHEMELoad Shed

Priority Load ID MW Shed

- ( )1 Aux B Pump.1 20( )MCC24AB LV Motors 1

.2 55 ( )Aux A Pump.2 00( )MCC24AB LV Motors

.2 55

#Desalter 1.4 25 2 Distillation

# .Unit 1 3 40 Distillation Unit

# .3 2 55

#3 Desalter 2


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conclusion

ILS is better than any of theconventional load shedding scheme

ILS is essential for indusrialapplication

Inteligent Load ils

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