Electrical Power Systems

Automatic Generation Control in a Restructured Power System 345
Similarly, DP2, DP3 and DP4 can easily be obtained from eqn. (13.8). In ig. 13.4(b), DPuc1 and
DPuc2 are uncontracted power demand (if any).
Also note that DPL1,LOC = DPL1 + DPL2 and DPL2,LOC = DPL3 + DPL4 . In the proposed AGC
implementation, contracted load is fed forward through the DPM matrix to GENCO setpoints.
This is shown in ig. 13.4(b) i.e., DP1, DP2, DP3 and DP4. The actual loads affect system dynamics
via the inputs DPL, LOC to the power system blocks. Any mismatch between actual and contracted
demands will result in a frequency deviation that will result in a frequency deviation that will
drive AGC to redispatch GENCOs according to ACE participation factors, i.e., a11, ¢ a12 ¢ , a21 ¢ ,
and a22 ¢ . The AGC scheme does not require measurement of actual loads. The inputs DPL1,LOC and DPL2,LOC in the block diagram of ig. 13.4 (a) & (b) are part of the power system model, not
part of AGC.
13.5 STATE SPACE REPRESENTATION O THE TWO-AREA SYSTEM
IN DEREGULATED ENVIRONMENT
The closed loop system shown in ig. 13.4 (b) is characterized in state space form as
X • = AX + BU + GP + gp ...(13.10)
or this case, A is 11 × 11 matrix, B is 11 × 2 matrix, G is 11 ´ 4 matrix and g is 11 × 2 matrix.
Details of this matrices are given below:
A =
L
NM
–1
Tp1
0
– K p1
Tp1
K p1
Tp1
0
K p1
Tp1
0 0 0 0 0
0
–1
Tp2
– Kp2 a12
Tp2
0 0 0 0
K p2
Tp2
0
K p2
Tp2
0
2pT12 0
–1
RT 1 g1
–2pT12
0
0
0
0
0
0
–1
Tt1 0
0
1
Tt1
–1
Tg1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
–1
RT 2 g2
0
0
0
0
0
0
0
0
–1
Tt2 0
1
Tt2
–1
Tg2
0
0
0
0
0
0
0
0
0
0
0
–1
R3Tg3 0
0
0
0
0
0
0
0
0
0
–1
Tt3 0
1
Tt3
–1
Tg3
0
0
0
0
0
0
0
–1
R T
0
0
0
0
0
0
0
0
0
0
0
0
0
0
–1
Tt4 0
1
Tt4
–1
T
4
g4 g4
O
QP