Information Technology Reference
In-Depth Information
p
P
Q
Q
q
Fig. 4.
Reference bidding curve for a Genco
zone. To this aim, a graph representation of the transmission grid (that defines the area
with relevant transmission constraints) is provided as input to the GAPEX (see Section
3.2). However, with respect to classical literature on power systems, the Italian market
introduces two modifications. Firstly, sellers are paid at the zonal prices, i.e., Loca-
tion Marginal Price (LMP), whereas buyers pay a unique national price (Prezzo Unico
Nazionale - PUN) common for the whole market and computed as a weighted average
of the zonal prices with respect to the zonal loads. Secondly, transmission power-flow
constraints differ according to the flow direction which results in doubling the number
of constraints related to the inter-zonal transmission limits. According to the specific
features of the Italian market, the results of the power exchange auction consist of a set
of the active powers
Q
i
and of a set of Locational Accepted Marginal Prices
LMP
k
for
each zone
k
∈{
1
,
2
, ..., K
}
.
3.2
Transmission Grid Model
The market clearing procedure described in Section 3.1 requires the definition of a
transmission network. The grid structure adopted in this paper is shown in Figure
??
and reproduces the exact zonal market structure and the relative maximum transmis-
sion capacities between neighboring zones of the Italian grid model as indicated by
Terna S.p.A. the Italian transmission system operator. The relevant areas of the network
correspond to physical geographic areas (e.g. Northern Italy, Sicily, Sardinia, etc.) in
which loads and generators, virtual production areas (i.e. foreign neighboring coun-
tries) or limited production areas (e.g. Priolo Gargallo) are present. It is worth remark-
ing that each zone is represented as a bus to whom generators and loads are connected.
Furthermore, the arches linking the zone represent the transmission connections and
account for the constraints in transmissions for the power flow. Finally, transmission
power-flow constraints differ according to the flow direction, e.g., power flowing from
Central-South to Central-North is subject to a transmission limit that is different from
the one relates to the power flowing from Central-North to Central-South. A detailed
discussion of the Italian transmission grid can be found in [23].
3.3
Genco Model
The supply side of the market is composed by Gencos submitting bids for each of
their power plants. In this paper attention is focussed on thermal power plants strategic
