src/oemof/solph/flows/_flow.py
# -*- coding: utf-8 -*-
"""
solph version of oemof.network.Edge
SPDX-FileCopyrightText: Uwe Krien <krien@uni-bremen.de>
SPDX-FileCopyrightText: Simon Hilpert
SPDX-FileCopyrightText: Cord Kaldemeyer
SPDX-FileCopyrightText: Stephan Günther
SPDX-FileCopyrightText: Birgit Schachler
SPDX-FileCopyrightText: jnnr
SPDX-FileCopyrightText: jmloenneberga
SPDX-FileCopyrightText: Pierre-François Duc
SPDX-FileCopyrightText: Saeed Sayadi
SPDX-FileCopyrightText: Johannes Kochems
SPDX-License-Identifier: MIT
"""
import math
import numbers
from collections.abc import Iterable
from warnings import warn
import numpy as np
from oemof.network import Edge
from oemof.tools import debugging
from oemof.solph._options import Investment
from oemof.solph._plumbing import sequence
class Flow(Edge):
r"""Defines a flow between two nodes.
Keyword arguments are used to set the attributes of this flow. Parameters
which are handled specially are noted below.
For the case where a parameter can be either a scalar or an iterable, a
scalar value will be converted to a sequence containing the scalar value at
every index. This sequence is then stored under the parameter's key.
Parameters
----------
nominal_value : numeric, :math:`P_{nom}` or
:class:`Investment <oemof.solph.options.Investment>`
The nominal value of the flow, either fixed or as an investement
optimisation. If this value is set the corresponding optimization
variable of the flow object will be bounded by this value
multiplied by min(lower bound)/max(upper bound).
variable_costs : numeric (iterable or scalar), default: 0, :math:`c`
The costs associated with one unit of the flow per hour. The
costs for each timestep (:math:`P_t \cdot c \cdot \delta(t)`)
will be added to the objective expression of the optimization problem.
max : numeric (iterable or scalar), :math:`f_{max}`
Normed maximum value of the flow. The flow absolute maximum will be
calculated by multiplying :attr:`nominal_value` with :attr:`max`
min : numeric (iterable or scalar), :math:`f_{min}`
Normed minimum value of the flow (see :attr:`max`).
fix : numeric (iterable or scalar), :math:`f_{fix}`
Normed fixed value for the flow variable. Will be multiplied with the
:attr:`nominal_value` to get the absolute value.
positive_gradient_limit : numeric (iterable, scalar or None)
the normed *upper bound* on the positive difference
(`flow[t-1] < flow[t]`) of two consecutive flow values.
negative_gradient_limit : numeric (iterable, scalar or None)
the normed *upper bound* on the negative difference
(`flow[t-1] > flow[t]`) of two consecutive flow values.
full_load_time_max : numeric, :math:`t_{full\_load,max}`
Upper bound on the summed flow expressed as the equivalent time that
the flow would have to run at full capacity to yield the same sum. The
value will be multiplied with the nominal_value to get the absolute
limit.
full_load_time_min : numeric, :math:`t_{full\_load,min}`
Lower bound on the summed flow expressed as the equivalent time that
the flow would have to run at full capacity to yield the same sum. The
value will be multiplied with the nominal_value to get the absolute
limit.
integer : boolean
Set True to bound the flow values to integers.
nonconvex : :class:`NonConvex <oemof.solph.options.NonConvex>`
If a nonconvex flow object is added here, the flow constraints will
be altered significantly as the mathematical model for the flow
will be different, i.e. constraint etc. from
:class:`~oemof.solph.flows._non_convex_flow_block.NonConvexFlowBlock`
will be used instead of
:class:`~oemof.solph.flows._simple_flow_block.SimpleFlowBlock`.
fixed_costs : numeric (iterable or scalar), :math:`c_{fixed}`
The fixed costs associated with a flow.
Note: These are only applicable for a multi-period model
and given on a yearly basis.
lifetime : int, :math:`l`
The lifetime of a flow (usually given in years);
once it reaches its lifetime (considering also
an initial age), the flow is forced to 0.
Note: Only applicable for a multi-period model.
age : int, :math:`a`
The initial age of a flow (usually given in years);
once it reaches its lifetime (considering also
an initial age), the flow is forced to 0.
Note: Only applicable for a multi-period model.
Notes
-----
See :py:class:`~oemof.solph.flows._simple_flow.SimpleFlowBlock`
for the variables, constraints and objective parts, that are created for
a Flow object.
Examples
--------
Creating a fixed flow object:
>>> f = Flow(nominal_value=2, fix=[10, 4, 4], variable_costs=5)
>>> f.variable_costs[2]
5
>>> f.fix[2]
4
Creating a flow object with time-depended lower and upper bounds:
>>> f1 = Flow(min=[0.2, 0.3], max=0.99, nominal_value=100)
>>> f1.max[1]
0.99
""" # noqa: E501
def __init__(
self,
nominal_value=None,
variable_costs=0,
min=None,
max=None,
fix=None,
positive_gradient_limit=None,
negative_gradient_limit=None,
full_load_time_max=None,
full_load_time_min=None,
integer=False,
bidirectional=False,
nonconvex=None,
lifetime=None,
age=None,
fixed_costs=None,
# --- BEGIN: To be removed for versions >= v0.6 ---
investment=None,
summed_max=None,
summed_min=None,
# --- END ---
custom_attributes=None,
):
# TODO: Check if we can inherit from pyomo.core.base.var _VarData
# then we need to create the var object with
# pyomo.core.base.IndexedVarWithDomain before any SimpleFlowBlock
# is created. E.g. create the variable in the energy system and
# populate with information afterwards when creating objects.
# --- BEGIN: The following code can be removed for versions >= v0.6 ---
if investment is not None:
msg = (
"For backward compatibility,"
" the option investment overwrites the option nominal_value."
+ " Both options cannot be set at the same time."
)
if nominal_value is not None:
raise AttributeError(msg)
else:
warn(msg, FutureWarning)
nominal_value = investment
msg = (
"\nThe parameter '{0}' is deprecated and will be removed "
+ "in version v0.6.\nUse the parameter '{1}', "
+ "to avoid this warning and future problems. "
)
if summed_max is not None:
warn(msg.format("summed_max", "full_load_time_max"), FutureWarning)
full_load_time_max = summed_max
if summed_min is not None:
warn(msg.format("summed_min", "full_load_time_min"), FutureWarning)
full_load_time_min = summed_min
# --- END ---
super().__init__()
if custom_attributes is not None:
for attribute, value in custom_attributes.items():
setattr(self, attribute, value)
self.nominal_value = None
self.investment = None
infinite_error_msg = (
"{} must be a finite value. Passing an infinite "
"value is not allowed."
)
if isinstance(nominal_value, numbers.Real):
if not math.isfinite(nominal_value):
raise ValueError(infinite_error_msg.format("nominal_value"))
self.nominal_value = nominal_value
elif isinstance(nominal_value, Investment):
self.investment = nominal_value
if fixed_costs is not None:
msg = (
"Be aware that the fixed costs attribute is only\n"
"meant to be used for multi-period models to depict "
"fixed costs that occur on a yearly basis.\n"
"If you wish to set up a multi-period model, explicitly "
"set the `periods` attribute of your energy system.\n"
"It has been decided to remove the `fixed_costs` "
"attribute with v0.2 for regular uses.\n"
"If you specify `fixed_costs` for a regular model, "
"this will simply be silently ignored."
)
warn(msg, debugging.SuspiciousUsageWarning)
self.fixed_costs = sequence(fixed_costs)
self.positive_gradient_limit = sequence(positive_gradient_limit)
self.negative_gradient_limit = sequence(negative_gradient_limit)
self.full_load_time_max = full_load_time_max
self.full_load_time_min = full_load_time_min
self.integer = integer
self.nonconvex = nonconvex
self.bidirectional = bidirectional
self.lifetime = lifetime
self.age = age
# It is not allowed to define min or max if fix is defined.
if fix is not None and (min is not None or max is not None):
raise AttributeError(
"It is not allowed to define `min`/`max` if `fix` is defined."
)
need_nominal_value = [
"fix",
"full_load_time_max",
"full_load_time_min",
"min",
"max",
]
sequences = ["fix", "variable_costs", "min", "max"]
if self.investment is None and self.nominal_value is None:
for attr in need_nominal_value:
if isinstance(eval(attr), Iterable):
the_attr = eval(attr)[0]
else:
the_attr = eval(attr)
if the_attr is not None:
raise AttributeError(
f"If {attr} is set in a flow (except InvestmentFlow), "
"nominal_value must be set as well.\n"
"Otherwise, it won't have any effect."
)
# minimum will be set even without nominal limit
# maximum and minimum (absolute values) should be always set,
# as nominal_value or invest might be defined later
if max is None:
max = 1
if min is None:
if bidirectional:
min = -1
else:
min = 0
for attr in sequences:
setattr(self, attr, sequence(eval(attr)))
if self.nominal_value is not None and not math.isfinite(self.max[0]):
raise ValueError(infinite_error_msg.format("max"))
# Checking for impossible gradient combinations
if self.nonconvex:
if self.nonconvex.positive_gradient_limit[0] is not None and (
self.positive_gradient_limit[0] is not None
or self.negative_gradient_limit[0] is not None
):
raise ValueError(
"You specified a positive gradient in your nonconvex "
"option. This cannot be combined with a positive or a "
"negative gradient for a standard flow!"
)
if self.nonconvex.negative_gradient_limit[0] is not None and (
self.positive_gradient_limit[0] is not None
or self.negative_gradient_limit[0] is not None
):
raise ValueError(
"You specified a negative gradient in your nonconvex "
"option. This cannot be combined with a positive or a "
"negative gradient for a standard flow!"
)
if (
self.investment
and self.nonconvex
and not np.isfinite(self.investment.maximum)
):
raise AttributeError(
"Investment into a non-convex flows needs a maximum "
+ "investment to be set."
)