Electrical Power Systems

Automatic Generation Control in a Restructured Power System 349
ig. 13.5(h): DP g4 (pu Mw) vs. time (sec).
ig. 13.5: Dynamic responses for Case-1.
igure 13.5 shows the results of this load change: area frequency deviations, actual power
flow on the tie-line ( in a direction from area-1 to area-2), and the generated powers of various
GENCOs, following a step change in the load demands of DISCO 1 and DISCO 2.
The frequency deviation in each area goes to zero in the steady state. Since, there are no
contracts of power between a GENCO in one area and a DISCO in another area, the scheduled
steady state power flow over the tie-line is zero.
In the steady state, generation of a GENCO must match the demand of the DISCOs in
contract with it. Expanding eqn. (13.8), we have,
DPi = cpfi1DPL1 + cpfi2DPL2 + cpfi3DPL3 + cpfi4DPL4 ...(13.13)
or the case under consideration, we have,
Similarly
DP g1,steady-state = DP 1 = 0.5 ´ 0.04 + 0.50 ´ 0.04 = 0.04 pu MW.
DP g2,steady-state = DP 2 = 0.04 pu MW
DP g3,steady-state = DP 3 = 0.0 pu MW
DP g4,steady-state = DP 4 = 0.0 pu MW
igure 13.5 also shows the actual generated powers of the GENCOs reach the desired
values in the steady state GENCO 3 and GENCO 4 are not contracted by any DISCO for a
transaction of power, hence, their change in generated power is zero in the steady-state, i.e.,
DP g3,steady-state = 0.0 pu MW and DP g4,steady-state = 0.0 pu MW.
Case-2
Here we will consider that all the DISCOs have contract with the GENCOs for power as per the
following DISCO participation Matrix (DPM):
DPM =
L
NM
050 . 025 . 00 . 030 .
020 . 025 . 00 . 00 .
00 . 025 . 10 . 070 .
030 . 025 . 00 . 00 .
O
QP