Page 73 - Decision Making Applications in Modern Power Systems

44 Decision Making Applications in Modern Power Systems

power system that includes wind and solar sources and load demand, which
are all associated with uncertainty. The robust optimization first finds the
worst case for the realization of uncertain parameters and then finds the opti-
mal scheduling of system flexibilities. The use of this method makes the sys-
tem robust against the uncertain parameters, and the value of objective
function remains reasonable even if the uncertain parameters do not take
their predicted values. In this way the risk of decision in scheduling and
operation of system can be controlled [28]. Some of the valuable works that
use the robust optimization method can be found in Refs. [29,30].

2.3 Problem formulation
In this section an example of modern power system scheduling problem is
presented, which involves the uncertainty. The microgrid concept as a futur-
istic distribution network is one of the modern power systems that has
attracted much interest in recent years. Each microgrid includes multiple
components: distributed generation (generation units and energy storage sys-
tem), different loads (controllable and noncontrollable load), switches, etc.
The penetration of renewable energy, such as photovoltaic (PV) and wind in
the microgrid with probabilistic nature, may cause the complexity for the
scheduling and operation of these networks. Fig. 2.1 shows that the 33-bus
microgrid consists of the wind and PV units as renewable energy resources,

Upstream network
Microgrid
1
21 20 19 18 2 22 23 24
G3
3
4
ESS
5
7 6 25 26 27 28
WT1
PV PV
29
G1
11 10 9 8 30
31
G2
32
12 13 14 15 16 17
WT2
Generator G
Line
Busbar
Energy storage system ESS
FIGURE 2.1 Schematic of microgrid with multiple units [31].