Constraints

Macro constraints are attached to Nodes, Transformations, Storages, and Edges through each component's constraints field. Most users interact with them through JSON input files, while modelers encounter them when building assets and custom components.

Constraint Library

The main user-facing list of available constraints is the Macro Constraint Library.

BalanceConstraint

BalanceConstraint deserves special attention because it now supports more than equality-only flow balances.

A balance may:

• include flow(...) terms with algebraic coefficients
• use ==, <=, or >=
• use scalar or time-varying coefficients

In practice, this means a modeler can define balances such as:

@add_balance(transform, :energy, flow(fuel_edge) == heat_rate * flow(elec_edge))
@add_balance(
    transform,
    :energy_lb,
    flow(fuel_edge) >= min_heat_rate * flow(elec_edge),
)
@add_stoichiometric_balance(
    transform,
    :conversion,
    fuel_rate * flow(fuel_edge) --> flow(elec_edge) + emission_rate * flow(co2_edge),
    flow(fuel_edge),
)

When BalanceConstraint is added to the host vertex, Macro compiles each named balance and applies the correct constraint sense at every time step.

Asset Modeler Note

If you are creating or updating an asset make function, prefer:

• @add_balance for general balances
• @add_stoichiometric_balance for --> conversion shorthand

over writing raw balance_data dictionaries by hand.