Page 241 - Decision Making Applications in Modern Power Systems

206 Decision Making Applications in Modern Power Systems

generation by the flexible resources in the face of the system peak load. In
this sense, different possible scenarios must be performed during the plan-
ning stage to guarantee that these actions will be able to be fulfilled.
To efficiently accomplish these goals, some aspects must be assessed at
different network levels [26] consisting of three main planes: resource, node,
and network-wide. The first level is featured at the resources connection, it
is typically related to the current status of the unit and its connection to the
grids, including aspects, such as generation availability or unavailability,
maximum generation capacity, actual state of charge (SOC), maximum
energy storage capacity, electrical connection to the grid (single or multi-
phase), and other features related to the respective unit. This last feature is
of uttermost importance since distribution system presents significant unbal-
ance between phases. The use of these units can be an efficient solution to
provide the system phase balance, especially in situations where the distribu-
tion network is operating islanded from the main grid.
The second level regards to the aggregation of flexible resources avail-
able for the contribution at the nodal level. In this level the maximum contri-
bution previously obtained is associated to other limiting factors that take
place at the nodal level such as conductors and transformers current levels.
The third level is the final barrier, it considers the available net contribution
obtained in the previous levels with the limits featured in a network-wide
perspective, like the ones imposed by central controllers.
A flowchart depicting the main restricting aspects of flexible resources
contribution is shown in Fig. 8.1.

Flexible resources Node Network
1 – SOC of EVs and storage units;
1 – Flexible resources maximum 1 – Nodal maximum generation
2 – Limiting factors at flexible generation contribution contribution
resource level:
Energy storage capacity 2 – Renewables contribution 2 – Limiting factors at network
Maximum generating power 3 – Limiting factors at nodal level: level:
Connection type (mono/bi/three Conductors Conductors
phase) Transformers Transformers
Integration period Voltage and current levels Voltage and current levels
Controllers
… … …

Flexible resources maximum Nodal maximum generation Network maximum generation
generation contribution contribution from flexible resources contribution from flexible resources

FIGURE 8.1 Flowchart main possible restricting aspects for flexible resources generating
contribution.