Modelling the maximum minimum margin objective#

Used input data#

Name

Symbol

Details

OptimisedFlowCnecs

\(c \in \mathcal{C} ^{o}\)

Set of FlowCnecs[1] which are ‘optimised’. OptimisedFlowCnecs is a subset of FlowCnecs: \(\mathcal{C} ^{o} \subset \mathcal{C}\)

upper threshold

\(f^{+}_{threshold} (c)\)

Upper threshold of FlowCnec \(c\), in MW, as defined in the CRAC

lower threshold

\(f^{-}_{threshold} (c)\)

Lower threshold of FlowCnec \(c\), in MW, defined in the CRAC

nominal voltage

\(U_{nom}(c)\)

Nominal voltage of OptimizedFlowCnec \(c\)

Used parameters#

Name

Details

type

Used to set the unit (AMPERE/MW) of the objective function

Defined optimization variables#

Name

Symbol

Details

Type

Index

Unit

Lower bound

Upper bound

Minimum margin

\(MM\)

the minimum margin over all OptimizedFlowCnecs

Real value

one scalar variable for the whole problem

MW or AMPERE (depending on objective-function unit)

\(-\infty\)

\(+\infty\)

Used optimization variables#

Name

Symbol

Defined in

Flow

\(F(c)\)

CoreProblemFiller

Defined constraints#

Define the minimum margin variable#

If objective-function is in MW#

\[ \begin{equation} MM \leq f^{+}_{threshold} (c) - F(c), \forall c \in \mathcal{C} ^{o} \end{equation} \]
\[ \begin{equation} MM \leq F(c) - f^{-}_{threshold} (c), \forall c \in \mathcal{C} ^{o} \end{equation} \]

Note that OptimizedFlowCnec might have only one threshold (upper or lower), in that case, only one of the two above constraints is defined.

If objective-function is in AMPERE#

\[ \begin{equation} MM \leq \frac{f^{+}_{threshold} (c) - F(c)}{c^{A->MW}(c)}, \forall c \in \mathcal{C} ^{o} \end{equation} \]
\[ \begin{equation} MM \leq \frac{F(c) - f^{-}_{threshold} (c)}{c^{A->MW}(c)}, \forall c \in \mathcal{C} ^{o} \end{equation} \]

where \(c^{A->MW}(c)\) is the conversion factor from AMPERE to MW of the FlowCnec c, calculated as below:

\[ \begin{equation} c^{A->MW}(c) = \frac{U_{nom}(c) \sqrt{3}}{1000} \end{equation} \]

There is a real difference between the two objective functions, as the most limiting OptimizedFlowCnec (i.e. the one which defines the minimum margin), can be different in MW and in A, depending on the nominal voltages Unom.

Contribution to the objective function#

The minimum margin should be maximised:

\[ \begin{equation} \min (-MM) \end{equation} \]