# -*- coding: utf-8 -*-
"""A constraint to have one common limit for several components.
SPDX-FileCopyrightText: Patrik Schönfeldt
SPDX-License-Identifier: MIT
"""
from pyomo import environ as po
[docs]def shared_limit(
model,
quantity,
limit_name,
components,
weights,
lower_limit=0,
upper_limit=None,
):
r"""
Adds a constraint to the given model that restricts
the weighted sum of variables to a corridor.
**The following constraints are build:**
.. math::
l_\mathrm{low} \le \sum v_i(t) \times w_i(t) \le l_\mathrm{up}
\forall t
Parameters
----------
model : oemof.solph.Model
Model to which the constraint is added.
limit_name : string
Name of the constraint to create
quantity : pyomo.core.base.var.IndexedVar
Shared Pyomo variable for all components of a type.
components : list of components
list of components of the same type
weights : list of numeric values
has to have the same length as the list of components
lower_limit : numeric
the lower limit
upper_limit : numeric
the lower limit
Examples
--------
The constraint can e.g. be used to define a common storage
that is shared between parties but that do not exchange
energy on balance sheet.
Thus, every party has their own bus and storage, respectively,
to model the energy flow. However, as the physical storage is shared,
it has a common limit.
>>> import pandas as pd
>>> from oemof import solph
>>> date_time_index = pd.date_range('1/1/2012', periods=5, freq='H')
>>> energysystem = solph.EnergySystem(timeindex=date_time_index)
>>> b1 = solph.Bus(label="Party1Bus")
>>> b2 = solph.Bus(label="Party2Bus")
>>> storage1 = solph.components.GenericStorage(
... label="Party1Storage",
... nominal_storage_capacity=5,
... inputs={b1: solph.Flow()},
... outputs={b1: solph.Flow()})
>>> storage2 = solph.components.GenericStorage(
... label="Party2Storage",
... nominal_storage_capacity=5,
... inputs={b1: solph.Flow()},
... outputs={b1: solph.Flow()})
>>> energysystem.add(b1, b2, storage1, storage2)
>>> components = [storage1, storage2]
>>> model = solph.Model(energysystem)
>>> solph.constraints.shared_limit(
... model,
... model.GenericStorageBlock.storage_content,
... "limit_storage", components,
... [1, 1], upper_limit=5)
"""
setattr(model, limit_name, po.Var(model.TIMESTEPS))
for t in model.TIMESTEPS:
getattr(model, limit_name)[t].setlb(lower_limit)
getattr(model, limit_name)[t].setub(upper_limit)
weighted_sum_constraint = limit_name + "_constraint"
def _weighted_sum_rule(m):
for ts in m.TIMESTEPS:
lhs = sum(quantity[c, ts] * w for c, w in zip(components, weights))
rhs = getattr(model, limit_name)[ts]
expr = lhs == rhs
getattr(m, weighted_sum_constraint).add(ts, expr)
setattr(
model,
weighted_sum_constraint,
po.Constraint(model.TIMESTEPS, noruleinit=True),
)
setattr(
model,
weighted_sum_constraint + "_build",
po.BuildAction(rule=_weighted_sum_rule),
)