Overview
The Antares-Xpansion package is based on the Antares software and its data format.
Antares-Xpansion is based on an already existing Antares study. Some of the capacities of this study, usually fixed as input in the Antares paradigm, will be optimized by the investment optimization module of the Antares-Xpansion package.
In order to run the investment optimization module, the Antares dataset must be enriched with - at least - two new files:
- A
candidates.inifile which contains the definition of investment candidates (which capacities of the Antares study are expandable? at what cost? with what limits? and so on), - A
settings.inifile which contains the settings of the Antares-Xpansion algorithm.
These two files must be located in the user/expansion/ directory of the Antares study (see Figure 1). The data they contain are neither visible nor modifiable in the Antares man-machine interface. These two files must therefore be handcrafted.
Figure 1 - Structure of an Antares study folder ready for an Antares-Xpansion optimization
Depending on the type of investment considered in the study, some modifications of the Antares study are necessary before filling the candidates.ini and settings.ini files.
Prepare the Antares study
The first step to set up an Antares-Xpansion study consists in defining investment candidates. Candidate capacities for investment are necessarily links from an Antares study. Investment candidates can be generation assets, or even flexibilities, by adopting a virtual node logic as described below.
 |  |  |
|---|---|---|
| (a) | (b) | (c) |
Figure 3 - Configuration of the Antares study for an investment in (a) transmission capacity (new line or grid reinforcement), (b) generation units and (c) storage.
The following sections describe the Antares modelling for different types of investment:
- Transmission capcity between two areas
- Thermal generation capacity
- Renewable generation capacity
- Flexibility
Investment in transmission capacity between two areas
The Antares link candidate for investment, shown in red in Figure 3 (a), is directly the interconnection for which the interest in increasing capacity is being studied.
- In the case of the construction of a new line, a link must be added in the Antares study between the two involved areas.
- In the case of a grid reinforcement between two already interconnected areas, the link between these two areas already exists in the Antares study. The parameter
already-installed-capacitywill be used in thecandidates.inifile to specify the capacity of the grid that already exists between the two zones. In this way, Antares-Xpansion will assess the economic interest of increasing this capacity beyond what is already installed.
Investment in thermal generation capacity
Suppose that the thermal generation capacity subject to expansion is physically located in area1 for the example in Figure 3 (b). As Antares-Xpansion only performs investment through links of the study, the modelling trick consists in creating a virtual node, here invest_semibase, connected to the physical node area1. The Antares link of the investment candidate is the link between these two nodes.
The generation unit, candidate for investment, must be defined by a thermal cluster with the following technical and economic parameters:
- It is located in the virtual node
invest_semibase. - Its market bid is equal to its marginal cost, which is the variable operating cost (in €/MWh) of the generation unit.
- It has an hourly availability time series that is always higher than the potential of the candidate, where by potential we mean the capacity correponding to the maximum investment that is allowed by the user (i.e.
max-investmentormax-units\( \times\)unit-size):- If the hourly availability time series of thermal generation are "*ready-made*” in
Antares, then the values of the time series must be filled in such a
way that they <strong>are always higher</strong>
than the candidate's potential.
- If the times series of thermal
generation are “*stochastic*” i.e. generated by Antares, then the
parameters for the generation of the series must be defined so that the availability is always higher than the potential
(<em>number of units</em> \\( \times\\) <em>nominal capacity</em> \\( >\\) <em>potential</em>, no outages
rate).
Other cluster parameters (<em>pmin</em>, <em>start-up costs</em>, etc.) can also be
defined. However, they will only be taken into account by
Antares-Xpansion if the unit-commitment type is set to <a href="settings-definition.md#uc_type" ><tt>expansion_accurate</tt></a>.
@subsection autotoc_md184 Investment in renewable generation capacity
Similarly as for thermal generation, the renewable
generation capacity subject to expansion, physically located for the
example in <strong>Figure 3 (b)</strong> in <tt>area1</tt>, must be moved to a virtual node
connected to the physical node <tt>area1</tt>. The Antares link for the investment candidate is the link between these two nodes.
For the type of renewable production of interest (wind or solar), a corresponding
production time-series (Antares wind or solar tab) must be defined in
the virtual node. The production time-series must be deterministic,
constant, and <strong>higher than the
potential</strong> (<tt>max-investment</tt>) of the candidate. The
parameters <a href="candidate-definition.md#indirect-link-profile" ><tt>[in]direct-link-profile</tt></a> from the <tt>candidates.ini</tt> file will then be used to define the
hourly load factor.
@subsection autotoc_md185 Investment in flexibility
The modeling of flexibilities, such as pumped storage, is generally based in Antares
on a set of virtual nodes/links and coupling constraints. To make
flexibility an investment candidate, a link must be identified in the
Antares modelling whose transmission capacity corresponds to the
capacity of the flexibility (e.g. its maximum power or the size
of a stock for example).
In the case of pumped storage in
<strong>Figure 3 (c)</strong>, the capacity of the pumped storage (equal to its pumping
and turbining capacity) is defined by the maximum possible flow on the
link between <tt>area1</tt> and <tt>hub</tt>: the investment
in the flexibility will be characterized by this link. The classical binding
constraints must be added in the Antares simulation to represent the
storage: for example a negative <tt>ROW Balance</tt> in <tt>psp-in</tt>,
positive <tt>ROW Balance</tt> in <tt>psp-out</tt> and the following constraint:
<img src="../../assets/media/image9.png" alt=""/>
@subsection autotoc_md186 Decommissioning decisions for thermal capacities
With Antares-Xpansion, it is possible to consider decommissioning decisions, the corresponding assets are referred as <em>decommissioning candidates</em>. The difference between <em>investment candidates</em> and <em>decommissioning candidates</em> lies in the fixed-cost annuity.
@subsubsection autotoc_md187 Fixed-cost annuity for investment candidates
The annuity of an <em>investment candidate</em> includes the sum of:
- Annualized investment costs,
- Fixed annual operation and maintenance costs.
In this configuration, Antares-Xpansion makes an economic choice by comparing the sum of these costs and the reduction in variable operating
costs (mainly fuel costs and penalties associated with loss of load)
due to the new investment.
@subsubsection autotoc_md188 Fixed-cost annuity for decommissioning candidates
The annuity for <em>decommissioning candidates</em> only includes the fixed annual
operation and maintenance costs. There is indeed no investment cost, since the decision consists only in choosing whether to maintain operation with the associated maintenance costs.
In this configuration,
Antares-Xpansion makes an economic choice by comparing the operation
and maintenance costs of a generation or transmission asset and the
savings induced on the variable costs of power system operation thanks to this asset.
The annualized investment costs are in this case considered
stranded and are not taken into account in this economic choice. The
potential of this type of candidate (i.e. its <a href="candidate-definition.md#max-investment" ><tt>max-investment</tt></a> or <a href="candidate-definition.md#max-units" ><tt>max-units</tt></a> \\( \times\\) <a href="candidate-definition.md#unit-size" ><tt>unit-size</tt></a>) corresponds to its decommissionable capacity,
or in other words, the candidate's already installed capacity that could be shut
down if it is no longer profitable for the power system.
Antares-Xpansion is not able to decommission generation units that are installed in the Antares study (i.e. located in "physical nodes"). However, we can use a modelling of <em>decommissioning candidates</em> with the same virtual node logic as the @ref "investment-in-thermal-generation-capacity" "investment in thermal generation capacity". Decommissioning candidates are existing physical facilities that should be moved to a virtual node.
For example, suppose that we aim at taking a decommissioning decision for thermal generation capacities that are physically located in <tt>area1</tt> of <strong>Figure 3 (b)</strong>. To be considered <em>decommissioning candidates</em>, these generation units must be moved to a virtual node (<tt>invest_semibase</tt> in <strong>Figure 3 (b)</strong>) with an hourly availability time series higher than their potential.
The decommissioning decision is made in Antares-Xpansion through the capacity of the link between <tt>area1</tt> and <tt>invest_semibase</tt>. Thus, the capacity invested by Antares-Xpansion on the link corresponds to the capacity that is <strong>not</strong> decommissioned.
Details on how to fill in the file <tt>candidates.ini</tt> for <em>decommissioning candidates</em> are given in the <a href="candidate-definition.md#decommissioning-candidates" >next part</a>.
@subsection autotoc_md189 Additional characteristics for links of investment candidates
In the four aforementioned cases, the link used to define investment
candidates (in red in <strong>Figure 3</strong>):
- must have the parameter <tt>transmission capacities = use
transmission capacities</tt>, and not <tt>set to null</tt> or <tt>set to
infinite</tt>,
- may have a <em>hurdle cost</em>, which will then be well taken into account
in the economic optimization of Antares-Xpansion,
- may be subject to binding constraints - provided that the Antares
version used is at least v6.1.3 - which will be well taken into
account in the simulations of system operation. These constraints
can possibly be constructed by the Kirchhoff constraint generator
and the information given in the impedances, loop flow and phase
shift columns of the link.
The direct and indirect transmission capacities of the link will be
modified by Antares-Xpansion. The values initially entered in the
<em>Trans.</em> <em>Capacity Direct</em> and <em>Trans. Capacity Indirect</em> columns do not
matter since they will be overwritten when the expansion problem is
solved. Note that the capacities of existing structures must be filled
in with the <a href="candidate-definition.md#already-installed-capacity" >
already-installed-capacity
- If the hourly availability time series of thermal generation are "*ready-made*” in
Antares, then the values of the time series must be filled in such a
way that they <strong>are always higher</strong>
than the candidate's potential.
- If the times series of thermal
generation are “*stochastic*” i.e. generated by Antares, then the
parameters for the generation of the series must be defined so that the availability is always higher than the potential
(<em>number of units</em> \\( \times\\) <em>nominal capacity</em> \\( >\\) <em>potential</em>, no outages
rate).
Other cluster parameters (<em>pmin</em>, <em>start-up costs</em>, etc.) can also be
defined. However, they will only be taken into account by
Antares-Xpansion if the unit-commitment type is set to <a href="settings-definition.md#uc_type" ><tt>expansion_accurate</tt></a>.
@subsection autotoc_md184 Investment in renewable generation capacity
Similarly as for thermal generation, the renewable
generation capacity subject to expansion, physically located for the
example in <strong>Figure 3 (b)</strong> in <tt>area1</tt>, must be moved to a virtual node
connected to the physical node <tt>area1</tt>. The Antares link for the investment candidate is the link between these two nodes.
For the type of renewable production of interest (wind or solar), a corresponding
production time-series (Antares wind or solar tab) must be defined in
the virtual node. The production time-series must be deterministic,
constant, and <strong>higher than the
potential</strong> (<tt>max-investment</tt>) of the candidate. The
parameters <a href="candidate-definition.md#indirect-link-profile" ><tt>[in]direct-link-profile</tt></a> from the <tt>candidates.ini</tt> file will then be used to define the
hourly load factor.
@subsection autotoc_md185 Investment in flexibility
The modeling of flexibilities, such as pumped storage, is generally based in Antares
on a set of virtual nodes/links and coupling constraints. To make
flexibility an investment candidate, a link must be identified in the
Antares modelling whose transmission capacity corresponds to the
capacity of the flexibility (e.g. its maximum power or the size
of a stock for example).
In the case of pumped storage in
<strong>Figure 3 (c)</strong>, the capacity of the pumped storage (equal to its pumping
and turbining capacity) is defined by the maximum possible flow on the
link between <tt>area1</tt> and <tt>hub</tt>: the investment
in the flexibility will be characterized by this link. The classical binding
constraints must be added in the Antares simulation to represent the
storage: for example a negative <tt>ROW Balance</tt> in <tt>psp-in</tt>,
positive <tt>ROW Balance</tt> in <tt>psp-out</tt> and the following constraint:
<img src="../../assets/media/image9.png" alt=""/>
@subsection autotoc_md186 Decommissioning decisions for thermal capacities
With Antares-Xpansion, it is possible to consider decommissioning decisions, the corresponding assets are referred as <em>decommissioning candidates</em>. The difference between <em>investment candidates</em> and <em>decommissioning candidates</em> lies in the fixed-cost annuity.
@subsubsection autotoc_md187 Fixed-cost annuity for investment candidates
The annuity of an <em>investment candidate</em> includes the sum of:
- Annualized investment costs,
- Fixed annual operation and maintenance costs.
In this configuration, Antares-Xpansion makes an economic choice by comparing the sum of these costs and the reduction in variable operating
costs (mainly fuel costs and penalties associated with loss of load)
due to the new investment.
@subsubsection autotoc_md188 Fixed-cost annuity for decommissioning candidates
The annuity for <em>decommissioning candidates</em> only includes the fixed annual
operation and maintenance costs. There is indeed no investment cost, since the decision consists only in choosing whether to maintain operation with the associated maintenance costs.
In this configuration,
Antares-Xpansion makes an economic choice by comparing the operation
and maintenance costs of a generation or transmission asset and the
savings induced on the variable costs of power system operation thanks to this asset.
The annualized investment costs are in this case considered
stranded and are not taken into account in this economic choice. The
potential of this type of candidate (i.e. its <a href="candidate-definition.md#max-investment" ><tt>max-investment</tt></a> or <a href="candidate-definition.md#max-units" ><tt>max-units</tt></a> \\( \times\\) <a href="candidate-definition.md#unit-size" ><tt>unit-size</tt></a>) corresponds to its decommissionable capacity,
or in other words, the candidate's already installed capacity that could be shut
down if it is no longer profitable for the power system.
Antares-Xpansion is not able to decommission generation units that are installed in the Antares study (i.e. located in "physical nodes"). However, we can use a modelling of <em>decommissioning candidates</em> with the same virtual node logic as the @ref "investment-in-thermal-generation-capacity" "investment in thermal generation capacity". Decommissioning candidates are existing physical facilities that should be moved to a virtual node.
For example, suppose that we aim at taking a decommissioning decision for thermal generation capacities that are physically located in <tt>area1</tt> of <strong>Figure 3 (b)</strong>. To be considered <em>decommissioning candidates</em>, these generation units must be moved to a virtual node (<tt>invest_semibase</tt> in <strong>Figure 3 (b)</strong>) with an hourly availability time series higher than their potential.
The decommissioning decision is made in Antares-Xpansion through the capacity of the link between <tt>area1</tt> and <tt>invest_semibase</tt>. Thus, the capacity invested by Antares-Xpansion on the link corresponds to the capacity that is <strong>not</strong> decommissioned.
Details on how to fill in the file <tt>candidates.ini</tt> for <em>decommissioning candidates</em> are given in the <a href="candidate-definition.md#decommissioning-candidates" >next part</a>.
@subsection autotoc_md189 Additional characteristics for links of investment candidates
In the four aforementioned cases, the link used to define investment
candidates (in red in <strong>Figure 3</strong>):
- must have the parameter <tt>transmission capacities = use
transmission capacities</tt>, and not <tt>set to null</tt> or <tt>set to
infinite</tt>,
- may have a <em>hurdle cost</em>, which will then be well taken into account
in the economic optimization of Antares-Xpansion,
- may be subject to binding constraints - provided that the Antares
version used is at least v6.1.3 - which will be well taken into
account in the simulations of system operation. These constraints
can possibly be constructed by the Kirchhoff constraint generator
and the information given in the impedances, loop flow and phase
shift columns of the link.
The direct and indirect transmission capacities of the link will be
modified by Antares-Xpansion. The values initially entered in the
<em>Trans.</em> <em>Capacity Direct</em> and <em>Trans. Capacity Indirect</em> columns do not
matter since they will be overwritten when the expansion problem is
solved. Note that the capacities of existing structures must be filled
in with the <a href="candidate-definition.md#already-installed-capacity" >
parameter in the candidates.ini file and not in the definition of the links in the Antares study.
