Electrical Power Systems

Automatic Generation Control: Conventional Scenario 325
Where Df 1 and D f 2 are frequency deviations in area-1 and area-2 respectively. Similarly
power flowing from area-2 to area-1 can be given as
Where
DPtie,21 = 2pT21 dzDf2dt-zDf1dti ...(12.25)
| V2|| V1|
T21 = cos(dº 2 – dº
P x
1) = synchronizing coefficient.
r2
21
Note that P r1 and P r2 are the rated capacity of area-1 and area-2, respectively,
rom eqns. (12.24) and (12.25) we get
Where
DP tie,21 = a 12DP tie,12
a12 = -Pr1
P
r2
...(12.26)
...(12.26)
With reference to eqn. (12.10), incremental power balance equation for area-1 can be
written as
DPg1 – DPL1 = 2H1 f º
d
dt (Df 1) + D 1Df 1 + DP tie,12
Taking Laplace transform of eqn. (12.27) and reorganizing, we get
K p1
D1(S) = DPg1( S) - DPL ( S) - DPtie,12(
S).
1+ ST
Where Kp1 = 1
D 1
; Tp1 = 2 1
Dfº 1
p1
...(12.27)
1 d i ...(12.28)
Block diagram representation of eqn. (12.28) is given in ig.12.17.
H
ig.12.17: Block diagram.
...(12.29)