Table 1 Summary of variables, parameters, indices, and constants used in the mathematical formulation.

From: Optimizing virtual power plant coordination through locational marginal flexibility under network constraints

Symbol

Description

\(\iota , \ell , \pi , \upsilon , \kappa , \tau\)

Indices for node, line, renewable unit, portfolio, generator, and time period

\(T^{long}\)

Set of long-term time horizons (seasonal, annual, rolling)

\(N, L, R_\iota , V_\iota , G_\iota\)

Sets of nodes, lines, renewable units, portfolios, and generators at node \(\iota\)

\(\vartheta ^{gen}_{\iota ,\kappa ,\tau }\)

Active power generation level of unit \(\kappa\) at node \(\iota\) and time \(\tau\)

\(\lambda ^{act}_{\iota ,\upsilon ,\tau }\)

Flexibility activation level of portfolio \(\upsilon\) at node \(\iota\) and time \(\tau\)

\(\zeta ^{curt}_{\iota ,\pi ,\tau }\)

Renewable curtailment at unit \(\pi\) of node \(\iota\) and time \(\tau\)

\(\zeta ^{emiss}_{\iota ,\pi ,\tau }\)

Carbon emission level associated with renewable \(\pi\) at node \(\iota\) and time \(\tau\)

\(\varepsilon ^{loss}_{\iota ,\tau }\)

Expected energy not served (EENS) or nodal loss at time \(\tau\)

\(\pi ^{viol}_{\ell ,\tau }\)

Probability of line \(\ell\) overload at time \(\tau\)

\(\eta ^{LMF}_{\iota ,\upsilon ,\tau }\)

Locational Marginal Flexibility (welfare sensitivity of flexibility)

\(\sigma ^{resp}_{\iota ,\upsilon ,\tau }\)

Binary indicator for service-level response satisfaction

\(\delta ^{life}_{\iota ,\upsilon }\)

Accumulated degradation (lifetime usage) of flexible resource \(\upsilon\)

\(\phi ^{quota}_{\iota ,\upsilon ,\tau }\)

Change in activation quota between rolling windows

\(\chi ^{rest}_{\iota ,\upsilon ,\tau }\)

Binary rest or recovery indicator after activation

\(\theta ^{flow}_{\ell ,\tau }\)

Power flow through line \(\ell\) at time \(\tau\)

\(\pi _{\ell ,\iota }\)

Power Transfer Distribution Factor (PTDF) from node \(\iota\) to line \(\ell\)

\(\varsigma ^{SOC}_{\iota ,\upsilon ,\tau }\)

State of charge for storage portfolio \(\upsilon\)

\(\Delta ^{max}_{\iota ,\upsilon }\)

Maximum allowable degradation or activation change

\(\Theta ^{max}_\ell\)

Thermal rating limit of line \(\ell\)

\(\Lambda ^{contract}_{\iota }\)

Contractual activation quota for node \(\iota\)

\(\omega ^{carb}, \xi ^{curt}, \gamma ^{res}\)

Coefficients for carbon, curtailment, and reserve penalties

\(\alpha ^{op}, \beta ^{inv}, \nu ^{deg}\)

Coefficients for operation, investment, and degradation costs

\(\chi ^{risk}\)

Weighting factor for reliability-related penalties

\(\Phi ^{feas}, \Theta ^{cut}\)

Feasibility and optimality cuts in decomposition process

\(\varepsilon\)

Wasserstein ball radius defining distributional ambiguity set

\(\Gamma\)

Risk or ambiguity tolerance bound

\(\rho ^{indoor}_{\iota ,\tau }\)

Indoor temperature level at node \(\iota\) and time \(\tau\)

\(\chi ^{ambient}_{\iota ,\tau }\)

Ambient temperature level at node \(\iota\) and time \(\tau\)

\(\alpha _i, \beta _i\)

Thermal response coefficients for HVAC load model

\(\kappa _1, \kappa _2\)

Degradation coefficients related to cycling and SoC deviation

\(\theta ^{fair}_{\iota ,\upsilon ,\tau }\)

Fairness penalty coefficient for activation changes