def generate_discretization_components_along_set(m, set_, active=True):
# What is a "discretization equation with respect to 's'"?
# Is it the component itself, or reference-to-slices of the
# component along set s?
#
# If we consider a "variable" to be something that maps time
# to some data, then a "differential variable" or "discretization
# equation" should also map time to some data...
for var in m.component_objects(pyo.Var, active=active):
if (isinstance(var, dae.DerivativeVar)
and set_ in ComponentSet(var.get_continuousset_list())):
block = var.parent_block()
# NOTE: Making some assumptions about the name and location
# of discretization equations.
con = block.find_component(var.local_name + DAE_DISC_SUFFIX)
var_map = dict(
(idx, pyo.Reference(slice_))
for idx, slice_ in slice_component_along_sets(var, (set_, )))
con_map = dict(
(idx, pyo.Reference(slice_))
for idx, slice_ in slice_component_along_sets(con, (set_, )))
if not active or con.active:
# We do not check the individual condata objects for activity...
for idx, var in var_map.items():
yield idx, con_map[idx], var
def make_model(self):
m = pyo.ConcreteModel()
m.x = pyo.Var(initialize=1.0)
m.y = pyo.Var(initialize=1.0)
m.u = pyo.Var(initialize=1.0)
m.v = pyo.Var(initialize=1.0)
m.con_1 = pyo.Constraint(expr=m.x * m.y == m.u)
m.con_2 = pyo.Constraint(expr=m.x**2 * m.y**3 == m.v)
m.con_3 = pyo.Constraint(
expr=self.con_3_body(m.x, m.y, m.u, m.v) == self.con_3_rhs())
m.con_4 = pyo.Constraint(
expr=self.con_4_body(m.x, m.y, m.u, m.v) == self.con_4_rhs())
epm_model = pyo.ConcreteModel()
epm_model.x = pyo.Reference(m.x)
epm_model.y = pyo.Reference(m.y)
epm_model.u = pyo.Reference(m.u)
epm_model.v = pyo.Reference(m.v)
epm_model.epm = ExternalPyomoModel(
[m.u, m.v],
[m.x, m.y],
[m.con_3, m.con_4],
[m.con_1, m.con_2],
)
epm_model.obj = pyo.Objective(expr=m.x**2 + m.y**2 + m.u**2 + m.v**2)
epm_model.egb = ExternalGreyBoxBlock()
epm_model.egb.set_external_model(epm_model.epm, inputs=[m.u, m.v])
return epm_model
def test_extra_category(self):
model = make_model(horizon=1, nfe=2)
time = model.time
t0 = time.first()
inputs = [model.flow_in]
measurements = [
pyo.Reference(model.conc[:, 'A']),
pyo.Reference(model.conc[:, 'B']),
]
disturbances = [
pyo.Reference(model.conc_in[:, 'A']),
pyo.Reference(model.conc_in[:, 'B']),
]
category_dict = {
VC.INPUT: inputs,
VC.MEASUREMENT: measurements,
VC.DISTURBANCE: disturbances,
}
db = DynamicBlock(
model=model,
time=time,
category_dict={None: category_dict},
)
db.construct()
db.set_sample_time(0.5)
db.vectors.input[:, t0].set_value(1.1)
db.vectors.measurement[:, t0].set_value(2.2)
db.vectors.disturbance[:, t0].set_value(3.3)
assert model.flow_in[t0].value == 1.1
assert model.conc[t0, 'A'].value == 2.2
assert model.conc[t0, 'B'].value == 2.2
assert model.conc_in[t0, 'A'].value == 3.3
assert model.conc_in[t0, 'B'].value == 3.3
def test_empty_category(self):
model = make_model(horizon=1, nfe=2)
time = model.time
t0 = time.first()
inputs = [model.flow_in]
measurements = [
pyo.Reference(model.conc[:, 'A']),
pyo.Reference(model.conc[:, 'B']),
]
category_dict = {
VC.INPUT: inputs,
VC.MEASUREMENT: measurements,
VC.ALGEBRAIC: [],
}
db = DynamicBlock(
model=model,
time=time,
category_dict={None: category_dict},
)
db.construct()
db.set_sample_time(0.5)
# Categories with no variables are removed.
# If they were retained, trying to iterate
# over, e.g., vectors.algebraic[:, :] would
# fail due to inconsistent dimension.
assert VC.ALGEBRAIC not in db.category_dict
def test_tag_ref(model):
m = model
m.rw = pyo.Reference(m.w[:, "a"])
m.ry = pyo.Reference(m.y)
rw = ModelTag(expr=m.rw, format_string="{:.3f}", doc="Tag for rw")
ry = ModelTag(expr=m.ry, format_string="{:.2f}", doc="Tag for ry")
m.w[1, "a"] = 3
assert str(rw[1]) == "3.000 kg"
assert rw[1].is_var
ry[:].set(2)
assert str(ry[None]) == "2.00 s"
def test_reference(self):
m = pyo.ConcreteModel()
m.v1 = pyo.Var()
m.ref = pyo.Reference(m.v1)
m.c1 = pyo.Constraint(expr=m.v1 == 1.0)
igraph = IncidenceGraphInterface(m)
self.assertEqual(igraph.incidence_matrix.shape, (1, 1))
def pressure_flow_default_callback(valve):
"""
Add the default pressure flow relation constraint. This will be used in the
valve model, a custom callback is provided.
"""
umeta = valve.config.property_package.get_metadata().get_derived_units
valve.Cv = pyo.Var(initialize=0.1,
doc="Valve flow coefficent",
units=umeta("amount") / umeta("time") /
umeta("pressure")**0.5)
valve.Cv.fix()
valve.flow_var = pyo.Reference(
valve.control_volume.properties_in[:].flow_mol)
valve.pressure_flow_equation_scale = lambda x: x**2
@valve.Constraint(valve.flowsheet().config.time)
def pressure_flow_equation(b, t):
Po = b.control_volume.properties_out[t].pressure
Pi = b.control_volume.properties_in[t].pressure
F = b.control_volume.properties_in[t].flow_mol
Cv = b.Cv
fun = b.valve_function[t]
return F**2 == Cv**2 * (Pi - Po) * fun**2
def __init__(self, expr, format_string="{}", doc="", display_units=None):
"""initialize a model tag instance.
Args:
expr: A Pyomo Var, Expression, Param, Reference, or unnamed
expression to tag. This can be a scalar or indexed.
format_string: A formating string used to print an elememnt of the
tagged expression (e.g. '{:.3f}').
doc: A description of the tagged quantity.
display_units: Pyomo units to display the quantity in. If a string
is provided it will be used to display as the unit, but will not
be used to convert units. If None, use native units of the
quantity.
"""
super().__init__()
self._format = format_string # format string for printing expression
if isinstance(expr, IndexedComponent_slice):
self._expression = pyo.Reference(
expr) # tag expression (can be unnamed)
else:
self._expression = expr
self._doc = doc # documentation for a tag
self._display_units = display_units # unit to display value in
self._cache_validation_value = {} # value when converted value stored
self._cache_display_value = {
} # value to display after unit conversions
self._name = None # tag name (just used to claify error messages)
self._root = None # use this to cache scalar tags in indexed parent
self._index = None # index to get cached converted value from parent
self._group = None # Group object if this is a member of a group
self._str_units = True # include units to stringify the tag
# if _set_in_display_units is True and no units are provided for for
# set, fix, setub, and setlb, the units will be assumed to be the
# display units. If it is false and no units are proided, the units are
# assumed to be the native units of the quantity
self._set_in_display_units = False
def plot_outlet_states_over_time(
m,
show=True,
prefix=None,
extra_states=None,
):
if prefix is None:
prefix = ""
if extra_states is None:
extra_states = []
x0 = m.fs.MB.gas_phase.length_domain.first()
x1 = m.fs.MB.solid_phase.length_domain.last()
state_slices = [
m.fs.MB.gas_phase.properties[:, x1].temperature,
m.fs.MB.gas_phase.properties[:, x1].pressure,
m.fs.MB.gas_phase.properties[:, x1].flow_mol,
m.fs.MB.gas_phase.properties[:, x1].mole_frac_comp["CH4"],
m.fs.MB.gas_phase.properties[:, x1].mole_frac_comp["H2O"],
m.fs.MB.gas_phase.properties[:, x1].mole_frac_comp["CO2"],
m.fs.MB.solid_phase.properties[:, x0].temperature,
m.fs.MB.solid_phase.properties[:, x0].flow_mass,
m.fs.MB.solid_phase.properties[:, x0].mass_frac_comp["Fe2O3"],
m.fs.MB.solid_phase.properties[:, x0].mass_frac_comp["Fe3O4"],
m.fs.MB.solid_phase.properties[:, x0].mass_frac_comp["Al2O3"],
]
state_refs = [pyo.Reference(slice_) for slice_ in state_slices]
state_refs.extend(extra_states)
for i, ref in enumerate(state_refs):
fig, ax = plot_time_indexed_variable(ref)
fig.savefig(prefix + "state%s.png" % i, transparent=True)
if show:
plt.show()
def test_tag_group(model):
m = model
g = ModelTagGroup()
m.rw = pyo.Reference(m.w[:, "a"])
g.add("w",
expr=m.rw,
format_string="{:.3f}",
doc="make sure this works",
display_units=pyo.units.g)
g.add("x", expr=m.x, format_string="{:.3f}")
g.add("y", expr=m.y, format_string="{:.3f}")
g.add("z", expr=m.z, format_string="{:.3f}")
g.add("e", expr=m.e, format_string="{:.3f}")
g.add("f", ModelTag(expr=m.f, format_string="{:.3f}"))
g.add("g", expr=m.g, format_string="{:.1f}", display_units="%")
assert g["w"].doc == "make sure this works"
g.str_include_units = True
assert g.str_include_units
assert g["w"].str_include_units
assert not g.set_in_display_units
assert not g["w"].set_in_display_units
g["w"].fix(2)
g["x"].fix(1)
g["y"].fix(3)
assert str(g["w"][1]) == "2000.000 g"
assert str(g["x"][1]) == "1.000 kg"
assert str(g["y"]) == "3.000 s"
g.str_include_units = False
assert str(g["w"][1]) == "2000.000"
assert str(g["x"][1]) == "1.000"
assert str(g["y"]) == "3.000"
g.set_in_display_units = True
g["w"][:].set(1000)
assert str(g["w"][1]) == "1000.000"
assert str(g["w"][2]) == "1000.000"
assert str(g["w"][2]) == "1000.000"
g.set_in_display_units = True
g["w"][:].set(2 * pyo.units.kg)
assert str(g["w"][1]) == "2000.000"
assert str(g["w"][2]) == "2000.000"
assert str(g["w"][2]) == "2000.000"
g["w"][:].fix(3 * pyo.units.kg)
assert str(g["w"][1]) == "3000.000"
assert str(g["w"][2]) == "3000.000"
assert str(g["w"][2]) == "3000.000"
g["w"][:].fix(4000)
assert str(g["w"][1]) == "4000.000"
assert str(g["w"][2]) == "4000.000"
assert str(g["w"][2]) == "4000.000"
def generate_diff_deriv_disc_components_along_set(m, set_, active=True):
for var in m.component_objects(pyo.Var, active=active):
if (isinstance(var, dae.DerivativeVar)
and set_ in ComponentSet(var.get_continuousset_list())):
block = var.parent_block()
con = block.find_component(var.local_name + DAE_DISC_SUFFIX)
state = var.get_state_var()
deriv_map = dict(
(idx, pyo.Reference(slice_))
for idx, slice_ in slice_component_along_sets(var, (set_, )))
disc_map = dict(
(idx, pyo.Reference(slice_))
for idx, slice_ in slice_component_along_sets(con, (set_, )))
state_map = dict(
(idx, pyo.Reference(slice_))
for idx, slice_ in slice_component_along_sets(state, (set_, )))
if not active or con.active:
for idx, deriv in deriv_map.items():
yield state_map[idx], deriv, disc_map[idx]
def make_model():
m = pyo.ConcreteModel()
m.time = pyo.Set(initialize=range(11))
m.space = pyo.Set(initialize=range(3))
m.comp = pyo.Set(initialize=['a', 'b'])
m.v1 = pyo.Var(m.time, m.space)
m.v2 = pyo.Var(m.time, m.space, m.comp)
@m.Block(m.time, m.space)
def b(b, t, x):
b.v3 = pyo.Var()
b.v4 = pyo.Var(m.comp)
m.v1_refs = [pyo.Reference(m.v1[:, x]) for x in m.space]
m.v2a_refs = [pyo.Reference(m.v2[:, x, 'a']) for x in m.space]
m.v2b_refs = [pyo.Reference(m.v2[:, x, 'b']) for x in m.space]
m.v3_refs = [pyo.Reference(m.b[:, x].v3) for x in m.space]
m.v4a_refs = [pyo.Reference(m.b[:, x].v4['a']) for x in m.space]
m.v4b_refs = [pyo.Reference(m.b[:, x].v4['a']) for x in m.space]
for t in m.time:
for ref in m.v1_refs:
ref[t] = 1.0 * t
for ref in m.v2a_refs + m.v2b_refs:
ref[t] = 2.0 * t
for ref in m.v3_refs:
ref[t] = 3.0 * t
for ref in m.v4a_refs + m.v4b_refs:
ref[t] = 4.0 * t
return m
def test_initialize_only_measurement_input(self):
model = make_model(horizon=1, nfe=2)
time = model.time
t0 = time.first()
inputs = [model.flow_in]
measurements = [
pyo.Reference(model.conc[:, 'A']),
pyo.Reference(model.conc[:, 'B']),
]
category_dict = {
VC.INPUT: inputs,
VC.MEASUREMENT: measurements,
}
db = DynamicBlock(
model=model,
time=time,
category_dict={None: category_dict},
)
db.construct()
db.set_sample_time(0.5)
db.mod.flow_in[:].set_value(3.0)
initialize_t0(db.mod)
copy_values_forward(db.mod)
db.mod.flow_in[:].set_value(2.0)
# Don't need to know any of the special categories to initialize
# by element. This is only because we have an implicit discretization.
db.initialize_by_solving_elements(solver)
t0 = time.first()
tl = time.last()
vectors = db.vectors
assert vectors.input[0, tl].value == 2.0
assert vectors.measurement[0, tl].value == pytest.approx(
3.185595567867036)
assert vectors.measurement[1, tl].value == pytest.approx(
1.1532474073395755)
assert model.dcdt[tl, 'A'].value == pytest.approx(0.44321329639889284)
assert model.dcdt[tl, 'B'].value == pytest.approx(0.8791007531878847)
def test_NmpcVector():
m = pyo.ConcreteModel()
m.coords = pyo.Set(initialize=[0, 1, 2, 3])
m.time = pyo.Set(initialize=[0.0, 0.5, 1.0, 1.5, 2.0])
@m.Block(m.coords)
def b(b, i):
b.var = NmpcVar(m.time)
m.vector = pyo.Reference(m.b[:].var[:], ctype=_NmpcVector)
assert type(m.vector) is _NmpcVector
# Test that `vector` is a proper reference
for i, t in m.coords * m.time:
assert m.vector[i, t] is m.b[i].var[t]
# Test that we can generate the underlying NmpcVars
for v, i in zip(m.vector._generate_referenced_vars(), m.coords):
assert v is m.b[i].var
# `set_setpoint`
m.vector.set_setpoint(3.14)
for i in m.coords:
assert m.b[i].var.setpoint == 3.14
setpoint = tuple(i / 10. for i in m.coords)
m.vector.set_setpoint(setpoint)
for i, sp in zip(m.coords, setpoint):
assert m.b[i].var.setpoint == sp
# `get_setpoint`
sp_get = tuple(m.vector.get_setpoint())
assert setpoint == sp_get
# `set_values`
val = -1.
m.vector.values = -1.
for i, t in m.coords * m.time:
assert m.b[i].var[t].value == val
newvals = tuple(i * 1.1 for i in m.coords)
m.vector.values = newvals
for i, val in zip(m.coords, newvals):
for t in m.time:
assert m.b[i].var[t].value == val
# `get_values`
val_lil = m.vector.values
for var_values, target_val in zip(val_lil, newvals):
for var_val in var_values:
assert var_val == target_val
def reshape(m):
time = m.time
# Create block to hold time-decomposition
m.time_block = pyo.Block(time)
# Identify time-indexed components
scalar_vars, dae_vars = flatten_dae_components(m, time, pyo.Var)
scalar_cons, dae_cons = flatten_dae_components(m, time, pyo.Constraint)
for t in time:
b = m.time_block[t]
var_list = []
b.vars = pyo.Reference([var[t] for var in dae_vars])
con_list = []
for con in dae_cons:
try:
condata = con[t]
con_list.append(condata)
except KeyError:
# For discretization equations, which are skipped at t0
pass
b.cons = pyo.Reference(con_list)
def TagReference(s, description=""):
"""
Create a Pyomo reference with an added description string attribute to
describe the reference. The intended use for these references is to create a
time-indexed reference to variables in a model corresponding to plant
measurment tags.
Args:
s: Pyomo time slice of a variable or expression
description (str): A description the measurment
Returns:
A Pyomo Reference object with an added doc attribute
"""
r = pyo.Reference(s)
r.description = description
return r
def build(self):
"""
Add model equations to the unit model. This is called by a default block
construnction rule when the unit model is created.
"""
super().build() # Basic unit model build/read config
config = self.config # shorter config pointer
# The thermodynamic expression writer object, te, writes expressions
# including external function calls to calculate thermodynamic quantities
# from a set of state variables.
_assert_properties(config.property_package)
te = ThermoExpr(blk=self, parameters=config.property_package)
eff = self.efficiency_pump = pyo.Var(self.flowsheet().config.time,
initialize=0.9,
doc="Pump efficiency")
self.efficiency_isentropic = pyo.Reference(self.efficiency_pump[:])
pratio = self.ratioP = pyo.Var(self.flowsheet().config.time,
initialize=0.7,
doc="Ratio of outlet to inlet pressure")
# Some shorter refernces to property blocks
properties_in = self.control_volume.properties_in
properties_out = self.control_volume.properties_out
@self.Expression(self.flowsheet().config.time,
doc="Thermodynamic work")
def work_fluid(b, t):
return properties_out[t].flow_vol * (self.deltaP[t])
@self.Expression(self.flowsheet().config.time,
doc="Work required to drive the pump.")
def shaft_work(b, t): # Early access to the outlet enthalpy and work
return self.work_fluid[t] / eff[t]
@self.Constraint(self.flowsheet().config.time)
def eq_work(b, t): # outlet enthalpy coens from energy balance
return self.control_volume.work[t] == self.shaft_work[t]
@self.Constraint(self.flowsheet().config.time)
def eq_pressure_ratio(b, t):
return (pratio[t] *
properties_in[t].pressure == properties_out[t].pressure)
def test_9():
# test with references the way we handle time indexing a lot in IDAES
rp = pyo.TransformationFactory("replace_variables")
block_set = {1,2,3}
m = pyo.ConcreteModel()
m.b1 = pyo.Block(block_set)
for i in block_set:
m.b1[i].x = pyo.Var(initialize=2)
m.y = pyo.Var([1,2,3], initialize=3)
m.xx = pyo.Reference(m.b1[:].x)
m.display()
m.e1 = pyo.Expression(expr=sum(m.xx[i] for i in m.xx))
m.e2 = pyo.Expression(expr=sum(m.b1[i].x for i in m.b1))
assert(pyo.value(m.e1) == 6)
assert(pyo.value(m.e2) == 6)
rp.apply_to(m, substitute=[(m.xx, m.y)])
assert(pyo.value(m.e1) == 9)
assert(pyo.value(m.e2) == 9)
def m(self):
m = pyo.ConcreteModel()
m.a = pyo.Var(initialize=0.25, bounds=(-0.5, 0.5))
m.b = b = pyo.Block()
b.a = pyo.Var([1, 2], bounds=(-10, 10))
m.c = pyo.Constraint(expr=(0, 1. / (m.a**2), 100))
b.c = pyo.Constraint([1, 2], rule=lambda b, i: (i - 1, b.a[i], i + 2))
b.d = pyo.Constraint(expr=b.a[1]**4 + b.a[2]**4 <= 4)
set_scaling_factor(b.d, 1e6)
b.o = pyo.Expression(expr=sum(b.a)**2)
m.o = pyo.Objective(expr=m.a + b.o)
# references are tricky, could cause a variable
# to be iterated over several times in
# component_data_objects
m.b_a = pyo.Reference(b.a)
return m
def _valve_pressure_flow_cb(b):
"""
For vapor F = Cv*sqrt(Pi**2 - Po**2)*f(x)
"""
umeta = b.config.property_package.get_metadata().get_derived_units
b.Cv = pyo.Var(initialize=0.1,
doc="Valve flow coefficent",
units=umeta("amount") / umeta("time") / umeta("pressure"))
b.Cv.fix()
b.flow_var = pyo.Reference(b.control_volume.properties_in[:].flow_mol)
b.pressure_flow_equation_scale = lambda x: x**2
@b.Constraint(b.flowsheet().time)
def pressure_flow_equation(b2, t):
Po = b2.control_volume.properties_out[t].pressure
Pi = b2.control_volume.properties_in[t].pressure
F = b2.control_volume.properties_in[t].flow_mol
Cv = b2.Cv
fun = b2.valve_function[t]
return F**2 == Cv**2 * (Pi**2 - Po**2) * fun**2
def update_metadata_model_references(model, metadata):
"""
Create model references from refernce strings in the metadata. This updates
the 'reference' field in the metadata.
Args:
model (pyomo.environ.Block): Pyomo model
metadata (dict): Tag metadata dictionary
Returns:
None
"""
for tag, md in metadata.items():
if md["reference_string"]:
try:
md["reference"] = pyo.Reference(
eval(md["reference_string"], {"m": model}))
except (KeyError, AttributeError, NameError):
warnings.warn(
"Tag reference {} not found".format(
md["reference_string"]),
UserWarning,
)
def main(plot_switch=False):
# This tests the same model constructed in the test_nmpc_constructor_1 file
m_controller = make_model(horizon=3, ntfe=30, ntcp=2, bounds=True)
sample_time = 0.5
m_plant = make_model(horizon=sample_time, ntfe=5, ntcp=2)
time_plant = m_plant.fs.time
solve_consistent_initial_conditions(m_plant, time_plant, solver)
#####
# Flatten and categorize controller model
#####
model = m_controller
time = model.fs.time
t0 = time.first()
t1 = time[2]
scalar_vars, dae_vars = flatten_dae_components(
model,
time,
pyo.Var,
)
scalar_cons, dae_cons = flatten_dae_components(
model,
time,
pyo.Constraint,
)
inputs = [
model.fs.mixer.S_inlet.flow_vol,
model.fs.mixer.E_inlet.flow_vol,
]
measurements = [
pyo.Reference(model.fs.cstr.outlet.conc_mol[:, 'C']),
pyo.Reference(model.fs.cstr.outlet.conc_mol[:, 'E']),
pyo.Reference(model.fs.cstr.outlet.conc_mol[:, 'S']),
pyo.Reference(model.fs.cstr.outlet.conc_mol[:, 'P']),
model.fs.cstr.outlet.temperature,
]
model.fs.cstr.control_volume.material_holdup[:, 'aq', 'Solvent'].fix()
model.fs.cstr.total_flow_balance.deactivate()
var_partition, con_partition = categorize_dae_variables_and_constraints(
model,
dae_vars,
dae_cons,
time,
input_vars=inputs,
)
controller = ControllerBlock(
model=model,
time=time,
measurements=measurements,
category_dict={None: var_partition},
)
controller.construct()
solve_consistent_initial_conditions(m_controller, time, solver)
controller.initialize_to_initial_conditions()
m_controller._dummy_obj = pyo.Objective(expr=0)
nlp = PyomoNLP(m_controller)
igraph = IncidenceGraphInterface(nlp)
m_controller.del_component(m_controller._dummy_obj)
diff_vars = [var[t1] for var in var_partition[VC.DIFFERENTIAL]]
alg_vars = [var[t1] for var in var_partition[VC.ALGEBRAIC]]
deriv_vars = [var[t1] for var in var_partition[VC.DERIVATIVE]]
diff_eqns = [con[t1] for con in con_partition[CC.DIFFERENTIAL]]
alg_eqns = [con[t1] for con in con_partition[CC.ALGEBRAIC]]
# Assemble and factorize "derivative Jacobian"
dfdz = nlp.extract_submatrix_jacobian(diff_vars, diff_eqns)
dfdy = nlp.extract_submatrix_jacobian(alg_vars, diff_eqns)
dgdz = nlp.extract_submatrix_jacobian(diff_vars, alg_eqns)
dgdy = nlp.extract_submatrix_jacobian(alg_vars, alg_eqns)
dfdzdot = nlp.extract_submatrix_jacobian(deriv_vars, diff_eqns)
fact = sps.linalg.splu(dgdy.tocsc())
dydz = fact.solve(dgdz.toarray())
deriv_jac = dfdz - dfdy.dot(dydz)
fact = sps.linalg.splu(dfdzdot.tocsc())
dzdotdz = -fact.solve(deriv_jac)
# Use some heuristic on the eigenvalues of the derivative Jacobian
# to identify fast states.
w, V = np.linalg.eig(dzdotdz)
w_max = np.max(np.abs(w))
fast_modes, = np.where(np.abs(w) > w_max / 2)
fast_states = []
for idx in fast_modes:
evec = V[:, idx]
_fast_states, _ = np.where(np.abs(evec) > 0.5)
fast_states.extend(_fast_states)
fast_states = set(fast_states)
# Store components necessary for model reduction in a model-
# independent form.
fast_state_derivs = [
pyo.ComponentUID(var_partition[VC.DERIVATIVE][idx].referent,
context=model) for idx in fast_states
]
fast_state_diffs = [
pyo.ComponentUID(var_partition[VC.DIFFERENTIAL][idx].referent,
context=model) for idx in fast_states
]
fast_state_discs = [
pyo.ComponentUID(con_partition[CC.DISCRETIZATION][idx].referent,
context=model) for idx in fast_states
]
# Perform pseudo-steady state model reduction on the fast states
# and re-categorize
for cuid in fast_state_derivs:
var = cuid.find_component_on(m_controller)
var.fix(0.0)
for cuid in fast_state_diffs:
var = cuid.find_component_on(m_controller)
var[t0].unfix()
for cuid in fast_state_discs:
con = cuid.find_component_on(m_controller)
con.deactivate()
var_partition, con_partition = categorize_dae_variables_and_constraints(
model,
dae_vars,
dae_cons,
time,
input_vars=inputs,
)
controller.del_component(model)
# Re-construct controller block with new categorization
measurements = [
pyo.Reference(model.fs.cstr.outlet.conc_mol[:, 'C']),
pyo.Reference(model.fs.cstr.outlet.conc_mol[:, 'E']),
pyo.Reference(model.fs.cstr.outlet.conc_mol[:, 'S']),
pyo.Reference(model.fs.cstr.outlet.conc_mol[:, 'P']),
]
controller = ControllerBlock(
model=model,
time=time,
measurements=measurements,
category_dict={None: var_partition},
)
controller.construct()
#####
# Construct dynamic block for plant
#####
model = m_plant
time = model.fs.time
t0 = time.first()
t1 = time[2]
scalar_vars, dae_vars = flatten_dae_components(
model,
time,
pyo.Var,
)
scalar_cons, dae_cons = flatten_dae_components(
model,
time,
pyo.Constraint,
)
inputs = [
model.fs.mixer.S_inlet.flow_vol,
model.fs.mixer.E_inlet.flow_vol,
]
measurements = [
pyo.Reference(model.fs.cstr.outlet.conc_mol[:, 'C']),
pyo.Reference(model.fs.cstr.outlet.conc_mol[:, 'E']),
pyo.Reference(model.fs.cstr.outlet.conc_mol[:, 'S']),
pyo.Reference(model.fs.cstr.outlet.conc_mol[:, 'P']),
]
model.fs.cstr.control_volume.material_holdup[:, 'aq', 'Solvent'].fix()
model.fs.cstr.total_flow_balance.deactivate()
var_partition, con_partition = categorize_dae_variables_and_constraints(
model,
dae_vars,
dae_cons,
time,
input_vars=inputs,
)
plant = DynamicBlock(
model=model,
time=time,
measurements=measurements,
category_dict={None: var_partition},
)
plant.construct()
p_t0 = plant.time.first()
c_t0 = controller.time.first()
p_ts = plant.sample_points[1]
c_ts = controller.sample_points[1]
controller.set_sample_time(sample_time)
plant.set_sample_time(sample_time)
# We now perform the "RTO" calculation: Find the optimal steady state
# to achieve the following setpoint
setpoint = [
(controller.mod.fs.cstr.outlet.conc_mol[0, 'P'], 0.4),
#(controller.mod.fs.cstr.outlet.conc_mol[0, 'S'], 0.01),
(controller.mod.fs.cstr.outlet.conc_mol[0, 'S'], 0.1),
(controller.mod.fs.cstr.control_volume.energy_holdup[0, 'aq'], 300),
(controller.mod.fs.mixer.E_inlet.flow_vol[0], 0.1),
(controller.mod.fs.mixer.S_inlet.flow_vol[0], 2.0),
(controller.mod.fs.cstr.volume[0], 1.0),
]
setpoint_weights = [
(controller.mod.fs.cstr.outlet.conc_mol[0, 'P'], 1.),
(controller.mod.fs.cstr.outlet.conc_mol[0, 'S'], 1.),
(controller.mod.fs.cstr.control_volume.energy_holdup[0, 'aq'], 1.),
(controller.mod.fs.mixer.E_inlet.flow_vol[0], 1.),
(controller.mod.fs.mixer.S_inlet.flow_vol[0], 1.),
(controller.mod.fs.cstr.volume[0], 1.),
]
# Some of the "differential variables" that have been fixed in the
# model file are different from the measurements listed above. We
# unfix them here so the RTO solve is not overconstrained.
# (The RTO solve will only automatically unfix inputs and measurements.)
controller.mod.fs.cstr.control_volume.material_holdup[0, ...].unfix()
controller.mod.fs.cstr.control_volume.energy_holdup[0, ...].unfix()
#controller.mod.fs.cstr.volume[0].unfix()
controller.mod.fs.cstr.control_volume.material_holdup[0, 'aq',
'Solvent'].fix()
controller.add_setpoint_objective(setpoint, setpoint_weights)
controller.solve_setpoint(solver)
# Now we are ready to construct the tracking NMPC problem
tracking_weights = [
*((v, 1.) for v in controller.vectors.differential[:, 0]),
*((v, 1.) for v in controller.vectors.input[:, 0]),
]
controller.add_tracking_objective(tracking_weights)
controller.constrain_control_inputs_piecewise_constant()
controller.initialize_to_initial_conditions()
# Solve the first control problem
controller.vectors.input[...].unfix()
controller.vectors.input[:, 0].fix()
solver.solve(controller, tee=True)
# For a proper NMPC simulation, we must have noise.
# We do this by treating inputs and measurements as Gaussian random
# variables with the following variances (and bounds).
cstr = controller.mod.fs.cstr
variance = [
(cstr.outlet.conc_mol[0.0, 'S'], 0.01),
(cstr.outlet.conc_mol[0.0, 'E'], 0.005),
(cstr.outlet.conc_mol[0.0, 'C'], 0.01),
(cstr.outlet.conc_mol[0.0, 'P'], 0.005),
(cstr.outlet.temperature[0.0], 1.),
(cstr.volume[0.0], 0.05),
]
controller.set_variance(variance)
measurement_variance = [
v.variance for v in controller.MEASUREMENT_BLOCK[:].var
]
measurement_noise_bounds = [(0.0, var[c_t0].ub)
for var in controller.MEASUREMENT_BLOCK[:].var]
mx = plant.mod.fs.mixer
variance = [
(mx.S_inlet_state[0.0].flow_vol, 0.02),
(mx.E_inlet_state[0.0].flow_vol, 0.001),
]
plant.set_variance(variance)
input_variance = [v.variance for v in plant.INPUT_BLOCK[:].var]
input_noise_bounds = [(0.0, var[p_t0].ub)
for var in plant.INPUT_BLOCK[:].var]
random.seed(100)
# Extract inputs from controller and inject them into plant
inputs = controller.generate_inputs_at_time(c_ts)
plant.inject_inputs(inputs)
# This "initialization" really simulates the plant with the new inputs.
plant.vectors.input[:, :].fix()
plant.initialize_by_solving_elements(solver)
plant.vectors.input[:, :].fix()
solver.solve(plant, tee=True)
for i in range(1, 11):
print('\nENTERING NMPC LOOP ITERATION %s\n' % i)
measured = plant.generate_measurements_at_time(p_ts)
plant.advance_one_sample()
plant.initialize_to_initial_conditions()
measured = apply_noise_with_bounds(
measured,
measurement_variance,
random.gauss,
measurement_noise_bounds,
)
controller.advance_one_sample()
controller.load_measurements(measured)
solver.solve(controller, tee=True)
inputs = controller.generate_inputs_at_time(c_ts)
inputs = apply_noise_with_bounds(
inputs,
input_variance,
random.gauss,
input_noise_bounds,
)
plant.inject_inputs(inputs)
plant.initialize_by_solving_elements(solver)
solver.solve(plant)
import pdb
pdb.set_trace()
def build(self):
"""
Building model
Args:
None
Returns:
None
"""
########################################################################
# Call UnitModel.build to setup dynamics and configure #
########################################################################
super().build()
self._process_config()
config = self.config
time = self.flowsheet().config.time
########################################################################
# Add control volumes #
########################################################################
hot_side = _make_heater_control_volume(
self,
config.hot_side_name,
config.hot_side_config,
dynamic=config.dynamic,
has_holdup=config.has_holdup,
)
cold_side = _make_heater_control_volume(
self,
config.cold_side_name,
config.cold_side_config,
dynamic=config.dynamic,
has_holdup=config.has_holdup,
)
# Add refernces to the hot side and cold side, so that we have solid
# names to refere to internally. side_1 and side_2 also maintain
# compatability with older models. Using add_object_reference keeps
# these from showing up when you iterate through pyomo compoents in a
# model, so only the user specified control volume names are "seen"
if not hasattr(self, "side_1"):
add_object_reference(self, "side_1", hot_side)
if not hasattr(self, "side_2"):
add_object_reference(self, "side_2", cold_side)
if not hasattr(self, "hot_side"):
add_object_reference(self, "hot_side", hot_side)
if not hasattr(self, "cold_side"):
add_object_reference(self, "cold_side", cold_side)
########################################################################
# Add variables #
########################################################################
# Use hot side units as basis
s1_metadata = config.hot_side_config.property_package.get_metadata()
f_units = s1_metadata.get_derived_units("flow_mole")
cp_units = s1_metadata.get_derived_units("heat_capacity_mole")
q_units = s1_metadata.get_derived_units("power")
u_units = s1_metadata.get_derived_units("heat_transfer_coefficient")
a_units = s1_metadata.get_derived_units("area")
temp_units = s1_metadata.get_derived_units("temperature")
self.overall_heat_transfer_coefficient = pyo.Var(
time,
domain=pyo.PositiveReals,
initialize=100.0,
doc="Overall heat transfer coefficient",
units=u_units,
)
self.area = pyo.Var(
domain=pyo.PositiveReals,
initialize=1000.0,
doc="Heat exchange area",
units=a_units,
)
self.heat_duty = pyo.Reference(cold_side.heat)
########################################################################
# Add ports #
########################################################################
i1 = self.add_inlet_port(name=f"{config.hot_side_name}_inlet",
block=hot_side,
doc="Hot side inlet")
i2 = self.add_inlet_port(name=f"{config.cold_side_name}_inlet",
block=cold_side,
doc="Cold side inlet")
o1 = self.add_outlet_port(name=f"{config.hot_side_name}_outlet",
block=hot_side,
doc="Hot side outlet")
o2 = self.add_outlet_port(name=f"{config.cold_side_name}_outlet",
block=cold_side,
doc="Cold side outlet")
# Using Andrew's function for now. I want these port names for backward
# compatablity, but I don't want them to appear if you iterate throught
# components and add_object_reference hides them from Pyomo.
if not hasattr(self, "inlet_1"):
add_object_reference(self, "inlet_1", i1)
if not hasattr(self, "inlet_2"):
add_object_reference(self, "inlet_2", i2)
if not hasattr(self, "outlet_1"):
add_object_reference(self, "outlet_1", o1)
if not hasattr(self, "outlet_2"):
add_object_reference(self, "outlet_2", o2)
if not hasattr(self, "hot_inlet"):
add_object_reference(self, "hot_inlet", i1)
if not hasattr(self, "cold_inlet"):
add_object_reference(self, "cold_inlet", i2)
if not hasattr(self, "hot_outlet"):
add_object_reference(self, "hot_outlet", o1)
if not hasattr(self, "cold_outlet"):
add_object_reference(self, "cold_outlet", o2)
########################################################################
# Add a unit level energy balance #
########################################################################
@self.Constraint(time, doc="Heat balance equation")
def unit_heat_balance(b, t):
return 0 == (hot_side.heat[t] +
pyunits.convert(cold_side.heat[t], to_units=q_units))
########################################################################
# Add some useful expressions for condenser performance #
########################################################################
@self.Expression(time, doc="Inlet temperature difference")
def delta_temperature_in(b, t):
return (hot_side.properties_in[t].temperature - pyunits.convert(
cold_side.properties_in[t].temperature, temp_units))
@self.Expression(time, doc="Outlet temperature difference")
def delta_temperature_out(b, t):
return (hot_side.properties_out[t].temperature - pyunits.convert(
cold_side.properties_out[t].temperature, temp_units))
@self.Expression(time, doc="NTU Based temperature difference")
def delta_temperature_ntu(b, t):
return (hot_side.properties_in[t].temperature_sat -
pyunits.convert(cold_side.properties_in[t].temperature,
temp_units))
@self.Expression(
time,
doc="Minimum product of flow rate and heat "
"capacity (always on tube side since shell side has phase change)")
def mcp_min(b, t):
return pyunits.convert(
cold_side.properties_in[t].flow_mol *
cold_side.properties_in[t].cp_mol_phase['Liq'],
f_units * cp_units)
@self.Expression(time, doc="Number of transfer units (NTU)")
def ntu(b, t):
return b.overall_heat_transfer_coefficient[t] * b.area / b.mcp_min[
t]
@self.Expression(time, doc="Condenser effectiveness factor")
def effectiveness(b, t):
return 1 - pyo.exp(-self.ntu[t])
@self.Expression(time, doc="Heat treansfer")
def heat_transfer(b, t):
return b.effectiveness[t] * b.mcp_min[t] * b.delta_temperature_ntu[
t]
########################################################################
# Add Equations to calculate heat duty based on NTU method #
########################################################################
@self.Constraint(time,
doc="Heat transfer rate equation based on NTU method")
def heat_transfer_equation(b, t):
return (pyunits.convert(cold_side.heat[t],
q_units) == self.heat_transfer[t])
@self.Constraint(
time, doc="Shell side outlet enthalpy is saturated water enthalpy")
def saturation_eqn(b, t):
return (hot_side.properties_out[t].enth_mol ==
hot_side.properties_in[t].enth_mol_sat_phase["Liq"])
def build(self):
"""
Build the PID block
"""
if isinstance(self.flowsheet().time, ContinuousSet):
# time may not be a continuous set if you have a steady state model
# in the steady state model case obviously the controller should
# not be active, but you can still add it.
if 'scheme' not in self.flowsheet().time.get_discretization_info():
# if you have a dynamic model, must do time discretization
# before adding the PID model
raise RunTimeError(
"PIDBlock must be added after time discretization")
super().build() # do the ProcessBlockData voodoo for config
# Check for required config
if self.config.pv is None:
raise ConfigurationError("Controller configuration requires 'pv'")
if self.config.output is None:
raise ConfigurationError(
"Controller configuration requires 'output'")
# Shorter pointers to time set information
time_set = self.flowsheet().time
t0 = time_set.first()
# Variable for basic controller settings may change with time.
self.setpoint = pyo.Var(time_set, doc="Setpoint")
self.gain = pyo.Var(time_set, doc="Controller gain")
self.time_i = pyo.Var(time_set, doc="Integral time")
self.time_d = pyo.Var(time_set, doc="Derivative time")
# Make the initial derivative term a variable so you can set it. This
# should let you carry on from the end of another time period
self.err_d0 = pyo.Var(doc="Initial derivative term", initialize=0)
self.err_d0.fix()
if not self.config.calculate_initial_integral:
self.err_i0 = pyo.Var(doc="Initial integral term", initialize=0)
self.err_i0.fix()
# Make references to the output and measured variables
self.pv = pyo.Reference(self.config.pv) # No duplicate
self.output = pyo.Reference(self.config.output) # No duplicate
# Create an expression for error from setpoint
@self.Expression(time_set, doc="Setpoint error")
def err(b, t):
return self.setpoint[t] - self.pv[t]
# Use expressions to allow the some future configuration
@self.Expression(time_set)
def pterm(b, t):
return -self.pv[t]
@self.Expression(time_set)
def dterm(b, t):
return -self.pv[t]
@self.Expression(time_set)
def iterm(b, t):
return self.err[t]
# Output limits parameter
self.limits = pyo.Param(["l", "h"],
mutable=True,
doc="controller output limits",
initialize={
"l": self.config.lower,
"h": self.config.upper
})
# Smooth min and max are used to limit output, smoothing parameter here
self.smooth_eps = pyo.Param(
mutable=True,
initialize=1e-4,
doc="Smoothing parameter for controller output limits")
# This is ugly, but want integral and derivative error as expressions,
# nice implementation with variables is harder to initialize and solve
@self.Expression(time_set, doc="Derivative error.")
def err_d(b, t):
if t == t0:
return self.err_d0
else:
return (b.dterm[t] - b.dterm[time_set.prev(t)])\
/(t - time_set.prev(t))
if self.config.pid_form == PIDForm.standard:
self._build_standard(time_set, t0)
else:
self._build_velocity(time_set, t0)
# Add the controller output constraint and limit it with smooth min/max
e = self.smooth_eps
h = self.limits["h"]
l = self.limits["l"]
@self.Constraint(time_set, doc="Controller output constraint")
def output_constraint(b, t):
if t == t0:
return pyo.Constraint.Skip
else:
return self.output[t] ==\
smooth_min(
smooth_max(self.unconstrained_output[t], l, e), h, e)
def test_scaling_without_rename(self):
m = pyo.ConcreteModel()
m.scaling_factor = pyo.Suffix(direction=pyo.Suffix.EXPORT)
m.v1 = pyo.Var(initialize=10)
m.v2 = pyo.Var(initialize=20)
m.v3 = pyo.Var(initialize=30)
def c1_rule(m):
return m.v1 == 1e6
m.c1 = pyo.Constraint(rule=c1_rule)
def c2_rule(m):
return m.v2 == 1e-4
m.c2 = pyo.Constraint(rule=c2_rule)
m.scaling_factor[m.v1] = 1.0
m.scaling_factor[m.v2] = 0.5
m.scaling_factor[m.v3] = 0.25
m.scaling_factor[m.c1] = 1e-5
m.scaling_factor[m.c2] = 1e5
values = {}
values[id(m.v1)] = (m.v1.value, m.scaling_factor[m.v1])
values[id(m.v2)] = (m.v2.value, m.scaling_factor[m.v2])
values[id(m.v3)] = (m.v3.value, m.scaling_factor[m.v3])
values[id(m.c1)] = (pyo.value(m.c1.body), m.scaling_factor[m.c1])
values[id(m.c2)] = (pyo.value(m.c2.body), m.scaling_factor[m.c2])
m.c2_ref = pyo.Reference(m.c2)
m.v3_ref = pyo.Reference(m.v3)
scale = pyo.TransformationFactory('core.scale_model')
scale.apply_to(m, rename=False)
self.assertTrue(hasattr(m, 'v1'))
self.assertTrue(hasattr(m, 'v2'))
self.assertTrue(hasattr(m, 'c1'))
self.assertTrue(hasattr(m, 'c2'))
orig_val, factor = values[id(m.v1)]
self.assertAlmostEqual(
m.v1.value,
orig_val*factor,
)
orig_val, factor = values[id(m.v2)]
self.assertAlmostEqual(
m.v2.value,
orig_val*factor,
)
orig_val, factor = values[id(m.c1)]
self.assertAlmostEqual(
pyo.value(m.c1.body),
orig_val*factor,
)
orig_val, factor = values[id(m.c2)]
self.assertAlmostEqual(
pyo.value(m.c2.body),
orig_val*factor,
)
orig_val, factor = values[id(m.v3)]
self.assertAlmostEqual(
m.v3_ref[None].value,
orig_val*factor,
)
# Note that because the model was not renamed,
# v3_ref is still intact.
lhs = m.c2.body
monom_factor = lhs.arg(0)
scale_factor = (m.scaling_factor[m.c2]/
m.scaling_factor[m.v2])
self.assertAlmostEqual(
monom_factor,
scale_factor,
)
def build(self):
"""
Begin building model (pre-DAE transformation).
Args:
None
Returns:
None
"""
# Call UnitModel.build to setup dynamics
super().build()
# Build Control Volume
self.control_volume = ControlVolume0DBlock(default={
"dynamic": self.config.dynamic,
"has_holdup": self.config.has_holdup,
"property_package": self.config.property_package,
"property_package_args": self.config.property_package_args})
self.control_volume.add_geometry()
self.control_volume.add_state_blocks(has_phase_equilibrium=False)
self.control_volume.add_material_balances(
balance_type=self.config.material_balance_type,)
self.control_volume.add_energy_balances(
balance_type=self.config.energy_balance_type,
has_heat_transfer=self.config.has_heat_transfer)
self.control_volume.add_momentum_balances(
balance_type=self.config.momentum_balance_type,
has_pressure_change=True)
self.flash = HelmPhaseSeparator(
default={
"dynamic": False,
"property_package": self.config.property_package,
}
)
self.mixer = Mixer(
default={
"dynamic": False,
"property_package": self.config.property_package,
"inlet_list": ["FeedWater", "SaturatedWater"],
"mixed_state_block": self.control_volume.properties_in,
}
)
# instead of creating a new block use control volume to return solution
# Inlet Ports
# FeedWater to Drum (from Pipe or Economizer)
self.feedwater_inlet = Port(extends=self.mixer.FeedWater)
# Sat water from water wall
self.water_steam_inlet = Port(extends=self.flash.inlet)
# Exit Ports
# Liquid to Downcomer
# self.liquid_outlet = Port(extends=self.mixer.outlet)
self.add_outlet_port('liquid_outlet', self.control_volume)
# Steam to superheaters
self.steam_outlet = Port(extends=self.flash.vap_outlet)
# constraint to make pressures of two inlets of drum mixer the same
@self.Constraint(self.flowsheet().config.time,
doc="Mixter pressure identical")
def mixer_pressure_eqn(b, t):
return b.mixer.SaturatedWater.pressure[t]*1e-6 == \
b.mixer.FeedWater.pressure[t]*1e-6
self.stream_flash_out = Arc(
source=self.flash.liq_outlet, destination=self.mixer.SaturatedWater
)
# Pyomo arc connect flash liq_outlet with mixer SaturatedWater inlet
pyo.TransformationFactory("network.expand_arcs").apply_to(self)
# Add object references
self.volume = pyo.Reference(self.control_volume.volume)
# Set references to balance terms at unit level
if (self.config.has_heat_transfer is True and
self.config.energy_balance_type != EnergyBalanceType.none):
self.heat_duty = pyo.Reference(self.control_volume.heat)
if (self.config.has_pressure_change is True and
self.config.momentum_balance_type != 'none'):
self.deltaP = pyo.Reference(self.control_volume.deltaP)
# Set Unit Geometry and Holdup Volume
self._set_geometry()
# Construct performance equations
self._make_performance()
def build(self):
"""
Build the PID block
"""
super().build() # do the ProcessBlockData voodoo for config
# Check for required config
if self.config.pv is None:
raise ConfigurationError("Controller configuration requires 'pv'")
if self.config.output is None:
raise ConfigurationError(
"Controller configuration requires 'output'")
# Shorter pointers to time set information
time_set = self.flowsheet().time
t0 = time_set.first()
# Variable for basic controller settings may change with time.
self.setpoint = pyo.Var(time_set, doc="Setpoint")
self.gain = pyo.Var(time_set, doc="Controller gain")
self.time_i = pyo.Var(time_set, doc="Integral time")
self.time_d = pyo.Var(time_set, doc="Derivative time")
# Make the initial derivative term a variable so you can set it. This
# should let you carry on from the end of another time period
self.err_d0 = pyo.Var(doc="Initial derivative term", initialize=0)
self.err_d0.fix()
if not self.config.calculate_initial_integral:
self.err_i0 = pyo.Var(doc="Initial integral term", initialize=0)
self.err_i0.fix()
# Make references to the output and measured variables
self.pv = pyo.Reference(self.config.pv) # No duplicate
self.output = pyo.Reference(self.config.output) # No duplicate
# Create an expression for error from setpoint
@self.Expression(time_set, doc="Setpoint error")
def err(b, t):
return self.setpoint[t] - self.pv[t]
# Use expressions to allow the some future configuration
@self.Expression(time_set)
def pterm(b, t):
return -self.pv[t]
@self.Expression(time_set)
def dterm(b, t):
return -self.pv[t]
@self.Expression(time_set)
def iterm(b, t):
return self.err[t]
# Output limits parameter
self.limits = pyo.Param(["l", "h"],
mutable=True,
doc="controller output limits",
initialize={
"l": self.config.lower,
"h": self.config.upper
})
# Smooth min and max are used to limit output, smoothing parameter here
self.smooth_eps = pyo.Param(
mutable=True,
initialize=1e-4,
doc="Smoothing parameter for controller output limits")
# This is ugly, but want integral and derivative error as expressions,
# nice implementation with variables is harder to initialize and solve
@self.Expression(time_set, doc="Derivative error.")
def err_d(b, t):
if t == t0:
return self.err_d0
else:
return (b.dterm[t] - b.dterm[time_set.prev(t)])\
/(t - time_set.prev(t))
# Want to fix the output varaible at the first time step to make
# solving easier. This calculates the initial integral error to line up
# with the initial output value, keeps the controller from initially
# jumping.
if self.config.calculate_initial_integral:
@self.Expression(doc="Initial integral error")
def err_i0(b):
return b.time_i[t0]*(b.output[0] - b.gain[t0]*b.pterm[t0]\
- b.gain[t0]*b.time_d[t0]*b.err_d[t0])/b.gain[t0]
# integral error
@self.Expression(time_set, doc="Integral error")
def err_i(b, t_end):
return b.err_i0 + sum((b.iterm[t] + b.iterm[time_set.prev(t)]) *
(t - time_set.prev(t)) / 2.0
for t in time_set if t <= t_end and t > t0)
# Calculate the unconstrainted controller output
@self.Expression(time_set, doc="Unconstrained contorler output")
def unconstrained_output(b, t):
return b.gain[t] * (b.pterm[t] + 1.0 / b.time_i[t] * b.err_i[t] +
b.time_d[t] * b.err_d[t])
# Add the controller output constraint and limit it with smooth min/max
e = self.smooth_eps
h = self.limits["h"]
l = self.limits["l"]
@self.Constraint(time_set, doc="Controller output constraint")
def output_constraint(b, t):
if t == t0:
return pyo.Constraint.Skip
else:
return self.output[t] ==\
smooth_min(
smooth_max(self.unconstrained_output[t], l, e), h, e)
def create_model():
"""Create the flowsheet and add unit models. Fixing model inputs is done
in a separate function to try to keep this fairly clean and easy to follow.
Args:
None
Returns:
(ConcreteModel) Steam cycle model
"""
############################################################################
# Flowsheet and Properties #
############################################################################
m = pyo.ConcreteModel(name="Steam Cycle Model")
m.fs = FlowsheetBlock(default={"dynamic":
False}) # Add steady state flowsheet
# A physical property parameter block for IAPWS-95 with pressure and enthalpy
# (PH) state variables. Usually pressure and enthalpy state variables are
# more robust especially when the phases are unknown.
m.fs.prop_water = iapws95.Iapws95ParameterBlock(
default={"phase_presentation": iapws95.PhaseType.MIX})
# A physical property parameter block with temperature, pressure and vapor
# fraction (TPx) state variables. There are a few instances where the vapor
# fraction is known and the temperature and pressure state variables are
# preferable.
m.fs.prop_water_tpx = iapws95.Iapws95ParameterBlock(
default={
"phase_presentation": iapws95.PhaseType.LG,
"state_vars": iapws95.StateVars.TPX,
})
############################################################################
# Turbine with fill-in reheat constraints #
############################################################################
# The TurbineMultistage class allows creation of the full turbine model by
# providing several configuration options, including: throttle valves;
# high-, intermediate-, and low-pressure sections; steam extractions; and
# pressure driven flow. See the IDAES documentation for details.
m.fs.turb = HelmTurbineMultistage(
default={
"property_package": m.fs.prop_water,
"num_parallel_inlet_stages": 4, # number of admission arcs
"num_hp": 7, # number of high-pressure stages
"num_ip": 10, # number of intermediate-pressure stages
"num_lp": 11, # number of low-pressure stages
"hp_split_locations": [4, 7], # hp steam extraction locations
"ip_split_locations": [5, 10], # ip steam extraction locations
"lp_split_locations": [4, 8, 10, 11
], # lp steam extraction locations
"hp_disconnect": [7], # disconnect hp from ip to insert reheater
"ip_split_num_outlets": {
10: 3
}, # number of split streams (default is 2)
})
# This model is only the steam cycle, and the reheater is part of the boiler.
# To fill in the reheater gap, a few constraints for the flow, pressure drop,
# and outlet temperature are added. A detailed boiler model can be coupled later.
#
# hp_split[7] is the splitter directly after the last HP stage. The splitter
# outlet "outlet_1" is always taken to be the main steam flow through the turbine.
# When the turbine model was instantiated the stream from the HP section to the IP
# section was omitted, so the reheater could be inserted.
# The flow constraint sets flow from outlet_1 of the splitter equal to
# flow into the IP turbine.
@m.fs.turb.Constraint(m.fs.time)
def constraint_reheat_flow(b, t):
return b.ip_stages[1].inlet.flow_mol[t] == b.hp_split[
7].outlet_1.flow_mol[t]
# Create a variable for pressure change in the reheater (assuming
# reheat_delta_p should be negative).
m.fs.turb.reheat_delta_p = pyo.Var(m.fs.time,
initialize=0,
units=pyo.units.Pa)
# Add a constraint to calculate the IP section inlet pressure based on the
# pressure drop in the reheater and the outlet pressure of the HP section.
@m.fs.turb.Constraint(m.fs.time)
def constraint_reheat_press(b, t):
return (b.ip_stages[1].inlet.pressure[t] ==
b.hp_split[7].outlet_1.pressure[t] + b.reheat_delta_p[t])
# Create a variable for reheat temperature and fix it to the desired reheater
# outlet temperature
m.fs.turb.reheat_out_T = pyo.Var(m.fs.time,
initialize=866,
units=pyo.units.K)
# Create a constraint for the IP section inlet temperature.
@m.fs.turb.Constraint(m.fs.time)
def constraint_reheat_temp(b, t):
return (b.ip_stages[1].control_volume.properties_in[t].temperature ==
b.reheat_out_T[t])
############################################################################
# Add Condenser/hotwell/condensate pump #
############################################################################
# Add a mixer for all the streams coming into the condenser. In this case the
# main steam, and the boiler feed pump turbine outlet go to the condenser
m.fs.condenser_mix = HelmMixer(
default={
"momentum_mixing_type": MomentumMixingType.none,
"inlet_list": ["main", "bfpt"],
"property_package": m.fs.prop_water,
})
# The pressure in the mixer comes from the connection to the condenser. All
# the streams coming in and going out of the mixer are equal, but we created
# the mixer with no calculation for the unit pressure. Here a constraint that
# specifies that the mixer pressure is equal to the main steam pressure is
# added. There is also a constraint that specifies the that BFP turbine outlet
# pressure is the same as the condenser pressure. Combined with the stream
# connections between units, these constraints effectively specify that the
# mixer inlet and outlet streams all have the same pressure.
@m.fs.condenser_mix.Constraint(m.fs.time)
def mixer_pressure_constraint(b, t):
return b.main_state[t].pressure == b.mixed_state[t].pressure
# The condenser model uses the physical property model with TPx state
# variables, while the rest of the model uses PH state variables. To
# translate between the two property calculations, an extra port is added to
# the mixer which contains temperature, pressure, and vapor fraction
# quantities.
m.fs.condenser_mix.outlet_tpx = Port(
initialize={
"flow_mol":
pyo.Reference(m.fs.condenser_mix.mixed_state[:].flow_mol),
"temperature":
pyo.Reference(m.fs.condenser_mix.mixed_state[:].temperature),
"pressure":
pyo.Reference(m.fs.condenser_mix.mixed_state[:].pressure),
"vapor_frac":
pyo.Reference(m.fs.condenser_mix.mixed_state[:].vapor_frac),
})
# Add the heat exchanger model for the condenser.
m.fs.condenser = HeatExchanger(
default={
"delta_temperature_callback": delta_temperature_underwood_callback,
"shell": {
"property_package": m.fs.prop_water_tpx
},
"tube": {
"property_package": m.fs.prop_water
},
})
m.fs.condenser.delta_temperature_out.fix(5)
# Everything condenses so the saturation pressure determines the condenser
# pressure. Deactivate the constraint that is used in the TPx version vapor
# fraction constraint and fix vapor fraction to 0.
m.fs.condenser.shell.properties_out[:].eq_complementarity.deactivate()
m.fs.condenser.shell.properties_out[:].vapor_frac.fix(0)
# There is some subcooling in the condenser, so we assume the condenser
# pressure is actually going to be slightly higher than the saturation
# pressure.
m.fs.condenser.pressure_over_sat = pyo.Var(
m.fs.time,
initialize=500,
doc="Pressure added to Psat in the condeser. This is to account for"
"some subcooling. (Pa)",
units=pyo.units.Pa)
# Add a constraint for condenser pressure
@m.fs.condenser.Constraint(m.fs.time)
def eq_pressure(b, t):
return (b.shell.properties_out[t].pressure ==
b.shell.properties_out[t].pressure_sat +
b.pressure_over_sat[t])
# Extra port on condenser to hook back up to pressure-enthalpy properties
m.fs.condenser.outlet_1_ph = Port(
initialize={
"flow_mol":
pyo.Reference(m.fs.condenser.shell.properties_out[:].flow_mol),
"pressure":
pyo.Reference(m.fs.condenser.shell.properties_out[:].pressure),
"enth_mol":
pyo.Reference(m.fs.condenser.shell.properties_out[:].enth_mol),
})
# Add the condenser hotwell. In steady state a mixer will work. This is
# where makeup water is added if needed.
m.fs.hotwell = HelmMixer(
default={
"momentum_mixing_type": MomentumMixingType.none,
"inlet_list": ["condensate", "makeup"],
"property_package": m.fs.prop_water,
})
# The hotwell is assumed to be at the same pressure as the condenser.
@m.fs.hotwell.Constraint(m.fs.time)
def mixer_pressure_constraint(b, t):
return b.condensate_state[t].pressure == b.mixed_state[t].pressure
# Condensate pump (Use compressor model, since it is more robust if vapor form)
m.fs.cond_pump = HelmIsentropicCompressor(
default={"property_package": m.fs.prop_water})
############################################################################
# Add low pressure feedwater heaters #
############################################################################
# All the feedwater heater sections will be set to use the Underwood
# approximation for LMTD, so create the fwh_config dict to make the config
# slightly cleaner
fwh_config = {
"delta_temperature_callback": delta_temperature_underwood_callback
}
# The feedwater heater model allows feedwater heaters with a desuperheat,
# condensing, and subcooling section to be added an a reasonably simple way.
# See the IDAES documentation for more information of configuring feedwater
# heaters
m.fs.fwh1 = FWH0D(
default={
"has_desuperheat": False,
"has_drain_cooling": False,
"has_drain_mixer": True,
"property_package": m.fs.prop_water,
"condense": fwh_config,
})
# pump for fwh1 condensate, to pump it ahead and mix with feedwater
m.fs.fwh1_pump = HelmIsentropicCompressor(
default={"property_package": m.fs.prop_water})
# Mix the FWH1 drain back into the feedwater
m.fs.fwh1_return = HelmMixer(
default={
"momentum_mixing_type": MomentumMixingType.none,
"inlet_list": ["feedwater", "fwh1_drain"],
"property_package": m.fs.prop_water,
})
# Set the mixer pressure to the feedwater pressure
@m.fs.fwh1_return.Constraint(m.fs.time)
def mixer_pressure_constraint(b, t):
return b.feedwater_state[t].pressure == b.mixed_state[t].pressure
# Add the rest of the low pressure feedwater heaters
m.fs.fwh2 = FWH0D(
default={
"has_desuperheat": True,
"has_drain_cooling": True,
"has_drain_mixer": True,
"property_package": m.fs.prop_water,
"desuperheat": fwh_config,
"cooling": fwh_config,
"condense": fwh_config,
})
m.fs.fwh3 = FWH0D(
default={
"has_desuperheat": True,
"has_drain_cooling": True,
"has_drain_mixer": True,
"property_package": m.fs.prop_water,
"desuperheat": fwh_config,
"cooling": fwh_config,
"condense": fwh_config,
})
m.fs.fwh4 = FWH0D(
default={
"has_desuperheat": True,
"has_drain_cooling": True,
"has_drain_mixer": False,
"property_package": m.fs.prop_water,
"desuperheat": fwh_config,
"cooling": fwh_config,
"condense": fwh_config,
})
############################################################################
# Add deaerator and boiler feed pump (BFP) #
############################################################################
# The deaerator is basically an open tank with multiple inlets. For steady-
# state, a mixer model is sufficient.
m.fs.fwh5_da = HelmMixer(
default={
"momentum_mixing_type": MomentumMixingType.none,
"inlet_list": ["steam", "drain", "feedwater"],
"property_package": m.fs.prop_water,
})
@m.fs.fwh5_da.Constraint(m.fs.time)
def mixer_pressure_constraint(b, t):
# Not sure about deaerator pressure, so assume same as feedwater inlet
return b.feedwater_state[t].pressure == b.mixed_state[t].pressure
# Add the boiler feed pump and boiler feed pump turbine
m.fs.bfp = HelmIsentropicCompressor(
default={"property_package": m.fs.prop_water})
m.fs.bfpt = HelmTurbineStage(default={"property_package": m.fs.prop_water})
# The boiler feed pump outlet pressure is the same as the condenser
@m.fs.Constraint(m.fs.time)
def constraint_out_pressure(b, t):
return (b.bfpt.control_volume.properties_out[t].pressure ==
b.condenser.shell.properties_out[t].pressure)
# Instead of specifying a fixed efficiency, specify that the steam is just
# starting to condense at the outlet of the boiler feed pump turbine. This
# ensures approximately the right behavior in the turbine. With a fixed
# efficiency, depending on the conditions you can get odd things like steam
# fully condensing in the turbine.
@m.fs.Constraint(m.fs.time)
def constraint_out_enthalpy(b, t):
return (
b.bfpt.control_volume.properties_out[t].enth_mol ==
b.bfpt.control_volume.properties_out[t].enth_mol_sat_phase["Vap"] -
200 * pyo.units.J / pyo.units.mol)
# The boiler feed pump power is the same as the power generated by the
# boiler feed pump turbine. This constraint determines the steam flow to the
# BFP turbine. The turbine work is negative for power out, while pump work
# is positive for power in.
@m.fs.Constraint(m.fs.time)
def constraint_bfp_power(b, t):
return 0 == b.bfp.control_volume.work[t] + b.bfpt.control_volume.work[t]
############################################################################
# Add high pressure feedwater heaters #
############################################################################
m.fs.fwh6 = FWH0D(
default={
"has_desuperheat": True,
"has_drain_cooling": True,
"has_drain_mixer": True,
"property_package": m.fs.prop_water,
"desuperheat": fwh_config,
"cooling": fwh_config,
"condense": fwh_config,
})
m.fs.fwh7 = FWH0D(
default={
"has_desuperheat": True,
"has_drain_cooling": True,
"has_drain_mixer": True,
"property_package": m.fs.prop_water,
"desuperheat": fwh_config,
"cooling": fwh_config,
"condense": fwh_config,
})
m.fs.fwh8 = FWH0D(
default={
"has_desuperheat": True,
"has_drain_cooling": True,
"has_drain_mixer": False,
"property_package": m.fs.prop_water,
"desuperheat": fwh_config,
"cooling": fwh_config,
"condense": fwh_config,
})
############################################################################
# Additional Constraints/Expressions #
############################################################################
# Add a few constraints to allow a for complete plant results despite the
# lack of a detailed boiler model.
# Boiler pressure drop
m.fs.boiler_pressure_drop_fraction = pyo.Var(
m.fs.time,
initialize=0.01,
doc="Fraction of pressure lost from boiler feed pump and turbine inlet",
)
@m.fs.Constraint(m.fs.time)
def boiler_pressure_drop(b, t):
return (m.fs.bfp.control_volume.properties_out[t].pressure *
(1 - b.boiler_pressure_drop_fraction[t]) ==
m.fs.turb.inlet_split.mixed_state[t].pressure)
# Again, since the boiler is missing, set the flow of steam into the turbine
# equal to the flow of feedwater out of the last feedwater heater.
@m.fs.Constraint(m.fs.time)
def close_flow(b, t):
return (m.fs.bfp.control_volume.properties_out[t].flow_mol ==
m.fs.turb.inlet_split.mixed_state[t].flow_mol)
# Calculate the amount of heat that is added in the boiler, including the
# reheater.
@m.fs.Expression(m.fs.time)
def boiler_heat(b, t):
return (b.turb.inlet_split.mixed_state[t].enth_mol *
b.turb.inlet_split.mixed_state[t].flow_mol -
b.fwh8.desuperheat.tube.properties_out[t].enth_mol *
b.fwh8.desuperheat.tube.properties_out[t].flow_mol +
b.turb.ip_stages[1].control_volume.properties_in[t].enth_mol *
b.turb.ip_stages[1].control_volume.properties_in[t].flow_mol -
b.turb.hp_split[7].outlet_1.enth_mol[t] *
b.turb.hp_split[7].outlet_1.flow_mol[t])
# Calculate the efficiency of the steam cycle. This doesn't account for
# heat loss in the boiler, so actual plant efficiency would be lower.
@m.fs.Expression(m.fs.time)
def steam_cycle_eff(b, t):
return -100 * b.turb.power[t] / b.boiler_heat[t]
############################################################################
## Create the stream Arcs ##
############################################################################
############################################################################
# Connect turbine and condenser units #
############################################################################
m.fs.EXHST_MAIN = Arc(source=m.fs.turb.outlet_stage.outlet,
destination=m.fs.condenser_mix.main)
m.fs.condenser_mix_to_condenser = Arc(source=m.fs.condenser_mix.outlet_tpx,
destination=m.fs.condenser.inlet_1)
m.fs.COND_01 = Arc(source=m.fs.condenser.outlet_1_ph,
destination=m.fs.hotwell.condensate)
m.fs.COND_02 = Arc(source=m.fs.hotwell.outlet,
destination=m.fs.cond_pump.inlet)
############################################################################
# Low pressure FWHs #
############################################################################
m.fs.EXTR_LP11 = Arc(source=m.fs.turb.lp_split[11].outlet_2,
destination=m.fs.fwh1.drain_mix.steam)
m.fs.COND_03 = Arc(source=m.fs.cond_pump.outlet,
destination=m.fs.fwh1.condense.inlet_2)
m.fs.FWH1_DRN1 = Arc(source=m.fs.fwh1.condense.outlet_1,
destination=m.fs.fwh1_pump.inlet)
m.fs.FWH1_DRN2 = Arc(source=m.fs.fwh1_pump.outlet,
destination=m.fs.fwh1_return.fwh1_drain)
m.fs.FW01A = Arc(source=m.fs.fwh1.condense.outlet_2,
destination=m.fs.fwh1_return.feedwater)
# fwh2
m.fs.FW01B = Arc(source=m.fs.fwh1_return.outlet,
destination=m.fs.fwh2.cooling.inlet_2)
m.fs.FWH2_DRN = Arc(source=m.fs.fwh2.cooling.outlet_1,
destination=m.fs.fwh1.drain_mix.drain)
m.fs.EXTR_LP10 = Arc(
source=m.fs.turb.lp_split[10].outlet_2,
destination=m.fs.fwh2.desuperheat.inlet_1,
)
# fwh3
m.fs.FW02 = Arc(source=m.fs.fwh2.desuperheat.outlet_2,
destination=m.fs.fwh3.cooling.inlet_2)
m.fs.FWH3_DRN = Arc(source=m.fs.fwh3.cooling.outlet_1,
destination=m.fs.fwh2.drain_mix.drain)
m.fs.EXTR_LP8 = Arc(source=m.fs.turb.lp_split[8].outlet_2,
destination=m.fs.fwh3.desuperheat.inlet_1)
# fwh4
m.fs.FW03 = Arc(source=m.fs.fwh3.desuperheat.outlet_2,
destination=m.fs.fwh4.cooling.inlet_2)
m.fs.FWH4_DRN = Arc(source=m.fs.fwh4.cooling.outlet_1,
destination=m.fs.fwh3.drain_mix.drain)
m.fs.EXTR_LP4 = Arc(source=m.fs.turb.lp_split[4].outlet_2,
destination=m.fs.fwh4.desuperheat.inlet_1)
############################################################################
# FWH5 (Deaerator) and boiler feed pump (BFP) #
############################################################################
m.fs.FW04 = Arc(source=m.fs.fwh4.desuperheat.outlet_2,
destination=m.fs.fwh5_da.feedwater)
m.fs.EXTR_IP10 = Arc(source=m.fs.turb.ip_split[10].outlet_2,
destination=m.fs.fwh5_da.steam)
m.fs.FW05A = Arc(source=m.fs.fwh5_da.outlet, destination=m.fs.bfp.inlet)
m.fs.EXTR_BFPT_A = Arc(source=m.fs.turb.ip_split[10].outlet_3,
destination=m.fs.bfpt.inlet)
m.fs.EXHST_BFPT = Arc(source=m.fs.bfpt.outlet,
destination=m.fs.condenser_mix.bfpt)
############################################################################
# High-pressure feedwater heaters #
############################################################################
# fwh6
m.fs.FW05B = Arc(source=m.fs.bfp.outlet,
destination=m.fs.fwh6.cooling.inlet_2)
m.fs.FWH6_DRN = Arc(source=m.fs.fwh6.cooling.outlet_1,
destination=m.fs.fwh5_da.drain)
m.fs.EXTR_IP5 = Arc(source=m.fs.turb.ip_split[5].outlet_2,
destination=m.fs.fwh6.desuperheat.inlet_1)
# fwh7
m.fs.FW06 = Arc(source=m.fs.fwh6.desuperheat.outlet_2,
destination=m.fs.fwh7.cooling.inlet_2)
m.fs.FWH7_DRN = Arc(source=m.fs.fwh7.cooling.outlet_1,
destination=m.fs.fwh6.drain_mix.drain)
m.fs.EXTR_HP7 = Arc(source=m.fs.turb.hp_split[7].outlet_2,
destination=m.fs.fwh7.desuperheat.inlet_1)
# fwh8
m.fs.FW07 = Arc(source=m.fs.fwh7.desuperheat.outlet_2,
destination=m.fs.fwh8.cooling.inlet_2)
m.fs.FWH8_DRN = Arc(source=m.fs.fwh8.cooling.outlet_1,
destination=m.fs.fwh7.drain_mix.drain)
m.fs.EXTR_HP4 = Arc(source=m.fs.turb.hp_split[4].outlet_2,
destination=m.fs.fwh8.desuperheat.inlet_1)
############################################################################
# Turn the Arcs into constraints and return the model #
############################################################################
pyo.TransformationFactory("network.expand_arcs").apply_to(m.fs)
return m
def create_model(
steady_state=True,
time_set=[0,3],
nfe=5,
calc_integ=True,
form=PIDForm.standard
):
""" Create a test model and solver
Args:
steady_state (bool): If True, create a steady state model, otherwise
create a dynamic model
time_set (list): The begining and end point of the time domain
nfe (int): Number of finite elements argument for the DAE transformation
calc_integ (bool): If Ture, calculate in the initial condition for
the integral term, else use a fixed variable (fs.ctrl.err_i0), flase
is the better option if you have a value from a previous time period
form: whether the equations are written in the standard or velocity form
Returns
(tuple): (ConcreteModel, Solver)
"""
if steady_state:
fs_cfg = {"dynamic":False}
model_name = "Steam Tank, Steady State"
else:
fs_cfg = {"dynamic":True, "time_set":time_set}
model_name = "Steam Tank, Dynamic"
m = pyo.ConcreteModel(name=model_name)
m.fs = FlowsheetBlock(default=fs_cfg)
# Create a property parameter block
m.fs.prop_water = iapws95.Iapws95ParameterBlock(
default={"phase_presentation":iapws95.PhaseType.LG})
# Create the valve and tank models
m.fs.valve_1 = SteamValve(default={
"dynamic":False,
"has_holdup":False,
"material_balance_type":MaterialBalanceType.componentTotal,
"property_package":m.fs.prop_water})
m.fs.tank = Heater(default={
"has_holdup":True,
"material_balance_type":MaterialBalanceType.componentTotal,
"property_package":m.fs.prop_water})
m.fs.valve_2 = SteamValve(default={
"dynamic":False,
"has_holdup":False,
"material_balance_type":MaterialBalanceType.componentTotal,
"property_package":m.fs.prop_water})
# Connect the models
m.fs.v1_to_t = Arc(source=m.fs.valve_1.outlet, destination=m.fs.tank.inlet)
m.fs.t_to_v2 = Arc(source=m.fs.tank.outlet, destination=m.fs.valve_2.inlet)
# The control volume block doesn't assume the two phases are in equilibrium
# by default, so I'll make that assumption here, I don't actually expect
# liquid to form but who knows. The phase_fraction in the control volume is
# volumetric phase fraction hence the densities.
@m.fs.tank.Constraint(m.fs.time)
def vol_frac_vap(b, t):
return b.control_volume.properties_out[t].phase_frac["Vap"]\
*b.control_volume.properties_out[t].dens_mol\
/b.control_volume.properties_out[t].dens_mol_phase["Vap"]\
== b.control_volume.phase_fraction[t, "Vap"]
# Add the stream constraints and do the DAE transformation
pyo.TransformationFactory('network.expand_arcs').apply_to(m.fs)
if not steady_state:
pyo.TransformationFactory('dae.finite_difference').apply_to(
m.fs, nfe=nfe, wrt=m.fs.time, scheme='BACKWARD')
# Fix the derivative variables to zero at time 0 (steady state assumption)
m.fs.fix_initial_conditions()
# A tank pressure reference that's directly time-indexed
m.fs.tank_pressure = pyo.Reference(
m.fs.tank.control_volume.properties_out[:].pressure)
# Add a controller
m.fs.ctrl = PIDBlock(default={"pv":m.fs.tank_pressure,
"output":m.fs.valve_1.valve_opening,
"upper":1.0,
"lower":0.0,
"calculate_initial_integral":calc_integ,
"pid_form":form})
m.fs.ctrl.deactivate() # Don't want controller turned on by default
# Fix the input variables
m.fs.valve_1.inlet.enth_mol.fix(50000)
m.fs.valve_1.inlet.pressure.fix(5e5)
m.fs.valve_2.outlet.pressure.fix(101325)
m.fs.valve_1.Cv.fix(0.001)
m.fs.valve_2.Cv.fix(0.001)
m.fs.valve_1.valve_opening.fix(1)
m.fs.valve_2.valve_opening.fix(1)
m.fs.tank.heat_duty.fix(0)
m.fs.tank.control_volume.volume.fix(2.0)
m.fs.ctrl.gain.fix(1e-6)
m.fs.ctrl.time_i.fix(0.1)
m.fs.ctrl.time_d.fix(0.1)
m.fs.ctrl.setpoint.fix(3e5)
# Initialize the model
solver = pyo.SolverFactory("ipopt")
solver.options = {'tol': 1e-6,
'linear_solver': "ma27",
'max_iter': 100}
for t in m.fs.time:
m.fs.valve_1.inlet.flow_mol = 100 # initial guess on flow
# simple initialize
m.fs.valve_1.initialize(outlvl=1)
_set_port(m.fs.tank.inlet, m.fs.valve_1.outlet)
m.fs.tank.initialize(outlvl=1)
_set_port(m.fs.valve_2.inlet, m.fs.tank.outlet)
m.fs.valve_2.initialize(outlvl=1)
solver.solve(m, tee=True)
# Return the model and solver
return m, solver
def main():
"""
"""
nxfe = 10
# NOTE: Default inputs: (128.2, 591.4)
ic_inputs = {
#"fs.MB.gas_phase.properties[*,0.0].flow_mol": 120.0,
#"fs.MB.solid_phase.properties[*,1.0].flow_mass": 550.0,
}
ic_model_params = {"nxfe": nxfe}
m_ic = get_steady_state_model(
ic_inputs,
solve_kwds={"tee": True},
model_params=ic_model_params,
)
time = m_ic.fs.time
scalar_data, dae_data = get_data_from_steady_model(m_ic, time)
# TODO: get steady state data (scalar and dae both necessary)
x0 = 0.0
x1 = 1.0
# These (as well as nxfe above) are the parameters for a small model
# that I'm using to test NMPC (defaults are 900, 15, 60), nxfe=10
horizon = 1800
tfe_width = 60
sample_width = 120
sample_points = [
# Calculate sample points first with integer arithmetic
# to avoid roundoff error
float(sample_width*i) for i in range(0, horizon//sample_width + 1)
]
horizon = float(horizon)
tfe_width = float(tfe_width)
model_params = {
"horizon": horizon,
"tfe_width": tfe_width,
"ntcp": 1,
"nxfe": nxfe,
}
# These are approximately the default values:
#disturbance_dict = {"CO2": 0.03, "H2O": 0.0, "CH4": 0.97}
disturbance_dict = {"CO2": 0.5, "H2O": 0.0, "CH4": 0.5}
disturbance = dict(
(
"fs.MB.gas_phase.properties[*,%s].mole_frac_comp[%s]" % (x0, j),
{(0.0, horizon): val},
)
for j, val in disturbance_dict.items()
)
# Create solver here as it is needed to solve for the setpoint
solver = pyo.SolverFactory("ipopt")
solver.options["linear_solver"] = "ma57"
solver.options["max_cpu_time"] = 1500
#
# Get setpoint data
#
sp_inputs = get_inputs_at_time(disturbance, horizon)
#sp_inputs.update({
# "fs.MB.gas_phase.properties[*,0.0].flow_mol": 272.8,
# "fs.MB.solid_phase.properties[*,1.0].flow_mass": 591.4,
#})
sp_model_params = {"nxfe": nxfe}
m_sp = get_steady_state_model(
sp_inputs,
solve_kwds={"tee": True},
model_params=sp_model_params,
)
time = m_sp.fs.time
space = m_sp.fs.MB.gas_phase.length_domain
t0 = time.first()
# Solve optimization problem for setpoint
sp_objective_states = [
"fs.MB.solid_phase.reactions[*,%s].OC_conv" % x0,
]
sp_target = {
"fs.MB.solid_phase.reactions[*,%s].OC_conv" % x0: 0.95,
}
m_sp.fs.MB.gas_inlet.flow_mol[:].unfix()
m_sp.setpoint_expr = get_tracking_cost_expressions(
sp_objective_states, time, sp_target
)
m_sp.objective = pyo.Objective(expr=m_sp.setpoint_expr[t0])
solver.solve(m_sp, tee=True)
scalar_vars, dae_vars = flatten_dae_components(m_sp, time, pyo.Var)
setpoint = {
str(pyo.ComponentUID(var.referent)): var[t0].value
for var in dae_vars
}
###
max_data = get_max_values_from_steady(m_sp)
variance_data = get_variance_of_time_slices(m_sp, time, space)
#weight_data = None
weight_data = {
name: 1.0/s if s != 0 else 1.0 for name, s in variance_data.items()
#name: 1/w if w != 0 else 1.0 for name, w in max_data.items()
# Note: 1/w**2 does not converge with states in objective...
}
objective_states = get_state_variable_names(space)
flattened_vars = [None, None]
m = get_model_for_dynamic_optimization(
sample_points=sample_points,
parameter_perturbation=disturbance,
model_params=model_params,
ic_scalar_data=scalar_data,
ic_dae_data=dae_data,
setpoint_data=setpoint,
objective_weights=weight_data,
objective_states=objective_states,
# this argument is a huge hack to get the flattened
# vars without having to do a bit more work.
flatten_out=flattened_vars,
)
add_constraints_for_missing_variables(m)
time = m.fs.time
t0 = time.first()
scalar_vars, dae_vars = flattened_vars
initialize_dynamic(m, dae_vars)
# Should we initialize to setpoint inputs?
#sp_input_dict = {
# "fs.MB.gas_phase.properties[*,0.0].flow_mol": {(t0, horizon): 250.0},
# "fs.MB.solid_phase.properties[*,1.0].flow_mass": {(t0, horizon): 591.4},
#}
#load_inputs_into_model(m, time, sp_input_dict)
# TODO: Should I set inlet flow rates to their target values for
# this simulation?
input_vardata = (
[m.fs.MB.gas_inlet.flow_mol[t] for t in time if t != t0]
+ [m.fs.MB.solid_inlet.flow_mass[t] for t in time if t != t0]
)
with TemporarySubsystemManager(
to_fix=input_vardata,
to_deactivate=[m.piecewise_constant_constraint],
):
print("Initializing by time element...")
with TIMER.context("elem-init"):
initialize_by_time_element(m, time, solver)
m.fs.MB.solid_phase.reactions[:,0.0].OC_conv.setlb(0.89)
print("Starting dynamic optimization solve...")
with TIMER.context("solve dynamic"):
solver.solve(m, tee=True)
extra_states = [
pyo.Reference(m.fs.MB.solid_phase.reactions[:,0.0].OC_conv),
]
plot_outlet_states_over_time(m, show=False, extra_states=extra_states)
inputs = [
"fs.MB.gas_phase.properties[*,0.0].flow_mol",
"fs.MB.solid_phase.properties[*,1.0].flow_mass",
]
plot_inputs_over_time(m, inputs, show=False)
print(m.tracking_cost.name)
for t in m.fs.time:
print(t, pyo.value(m.tracking_cost[t]))
print()
