Page 279 - Mathematical Models and Algorithms for Power System Optimization

Optimization Method for Load Frequency Feed Forward Control 271

Fig. 7.23
Test results of central estimator. (Comparison of step functions ①, ② for given system
load disturbance ΔP L )

7.8.4 Simulation Results of Compensation Controller

7.8.4.1 Difference T ¼1s

The transfer function of the compensator of thermal generating unit is:
2
1 1:0999B +0:203B 0:0099B 3
H C ¼ (7.124)
3
0:24B 0:107B 0:04B 3
Corresponding control law for the compensator:
2
1 1:0999B +0:203B 0:0099B 3
Δu 1 kðÞ ¼ ΔP L1 kðÞ (7.125)
2
0:24B 0:107B 0:04B 3
where B means one step shift operator, or:
ð
ð
Δu 1 kðÞ ¼ 0:449Δu 1 k 1ð Þ +0:16Δu 1 k 2Þ +4:17ΔP L k +1Þ
(7.126)
ð
4:59ΔP L1 kðÞ +0:84ΔP L1 k 1ð Þ 0:041ΔP L1 k 2Þ
For the hydro generating unit:
2
0:00204B +0:08954B 0:07149B 3
G 1 ¼
2
1 1:265B +0:3B 0:02B 3
Because the numerator of G 1 has a root of no less than 1 and is irreversible, it is thus unable to
solve H C . Test shows that, letting H C ¼1 can achieve good results. Similarly, let:

Δu 2 kðÞ ¼ ΔP L2 kðÞ (7.127)
Test results are shown in Fig. 7.24.
The results of the controller in Fig. 7.14 with the conventional integrated feedback control are
also shown for comparison. It can be seen from the curves that the compensator shown in