Page 253 - Mathematical Models and Algorithms for Power System Optimization

Optimization Method for Load Frequency Feed Forward Control 245

Finally, the equivalent Eq. (7.43) can be simplified as:

M e Δ _ ω e + DΔω e ¼ ΔP Te ΔP L
In this chapter, the five-unit system (including four hydro units and one thermal unit) is
considered, and the block diagram of equivalent generator model is detailed in Fig. 7.11, where
X
M K Δω K
W SUM ¼ X
M K

As shown in Fig. 7.11, the task of load frequency control for a power system is to search for the
control law Δu i under any load disturbance ΔP L to carry out stable frequency control. That is, to
maintain the frequency changes in a relatively small range, and to carry out fast, stable,
and accurate frequency control.

Fig. 7.11
Block diagram of equivalent generator model.

7.5 Hierarchical Estimation for the Power System

After formulating the power system model, the system can be then controlled. To control a
system, it is required to understand the system state, that is, to make state estimation to the
system. The geographical distribution properties of all power plants in the power system
facilitate the application of decomposition method in the system analysis and control.
Naturally, the power system divides the system into three levels: the bottom is the power station
or generating units, the middle is dispatching centers at all levels, and the highest is a joint