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Ain Shams UniversityFaculty of EngineeringElect. Power & MachinesDept.

4thear Power SectionPower System Analysis !""

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Sheet '()

Electromechanical *ransient in SEPS'E+ual Area ,riterion)

Appreviations:

EPS : Electrical power system.

IB : Infinite bus.

TSM: Transient stability margin.

CA : Clearing angle.

CCA: Critical clearing angle.TL : Transmission line.

Simplified EPS:

. !i"e t#e general formulation of t#e met#o$ of e%ual areas.

&. A generator is $eli"ering '() of power w#ic# it is capable of $eli"ering

t#roug# a TL to an IB. a fault occurs w#ic# increases t#e reactance between

t#e generator an$ t#e IB to *(() of t#e "alue before fault. +#en t#e fault

is isolate$ t#e ma,imum power w#ic# can be $eli"ere$ is -') of t#e

original ma,. "alue. etermine t#e CCA for t#e con$itions $escribe$.

/. 0or t#e system s#own in 0ig. 1 Calculate t#e CCA if a /2p# S.C. occurs at

t#e beginning of one of t#e TL. All parameters are gi"en in p.u. as follows:

T3 T&3 T/3 T*3 (.45 TL 3 (.&*5 63 (.&75 6&3 (.4

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*. A simplifie$ EPS is sub8ecte$ to a /2p#. 0ault. etermine t#e fault CA

maintaining a TSM of ( )1 also fin$ t#e ma,imum "alue of t#e rotor

angle in t#e process of oscillations. System power2angle c#aracteristics are

pure sinusoi$al at all operating con$itions. System capacities are *1 1 an$ /

p.u. at pre2fault. fault an$ post2fault con$itions. Two p.u. power is

transmitte$ to t#e IB in normal operating con$itions.

'. A generator is $eli"ering (.&' of Pma,to an IB t#roug# a T.L. A fault occurs

suc# t#at t#e reactance between t#e generator an$ t#e IB is increase$ to two

times its pre2fault "alue. 0in$ t#e ma,imum "alue of t#e rotor angle in t#e

process of oscillations in t#e case of sustaine$ fault.

4. A simplifie$ EPS is sub8ecte$ to a &2p# S.C. at t#e beginning of one of t#e

TL at instant to 9'o 3 /(;1 $uring an inter"al t1 at t93 '&;1 t#e &2p#

S.C. $e"elope$ to a /2p# one1 an$ t#en at instant t&9&3 -/;1 t#e faulty line

is $isconnecte$. If t#e ma,imum power t#at can be transmitte$ in pre2fault1

fault an$ post2fault con$itions are &1 (.7 an$ .4 p.u. respecti"ely. C#ec