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Merge pull request #3177 from pybamm-team/issue-3101-experiment-start…
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…ing-solution

Fix `starting_solution` issues
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@rtimms
rtimms authored Sep 15, 2023
2 parents e3b1eb5 + 9efd58b commit 6622ec6
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10 changes: 7 additions & 3 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -15,10 +15,14 @@
- Fixed a bug where the "basic" lithium-ion models gave incorrect results when using nonlinear particle diffusivity ([#3207](https://github.com/pybamm-team/PyBaMM/pull/3207))
- Particle size distributions now work with SPMe and NewmanTobias models ([#3207](https://github.com/pybamm-team/PyBaMM/pull/3207))
- Fix to simulate c_rate steps with drive cycles ([#3186](https://github.com/pybamm-team/PyBaMM/pull/3186))
- Parameters in `Prada2013` have been updated to better match those given in the paper, which is a 2.3 Ah cell, instead of the mix-and-match with the 1.1 Ah cell from Lain2019.
- Error generated when invalid parameter values are passed. ([#3132](https://github.com/pybamm-team/PyBaMM/pull/3132))
- Thevenin() model is now constructed with standard variables: `Time [s], Time [min], Time [h]` ([#3143](https://github.com/pybamm-team/PyBaMM/pull/3143))
- Always save last cycle in experiment, to fix issues with `starting_solution` and `last_state` ([#3177](https://github.com/pybamm-team/PyBaMM/pull/3177))
- Fix simulations with `starting_solution` to work with `start_time` experiments ([#3177](https://github.com/pybamm-team/PyBaMM/pull/3177))
- Fix SEI Example Notebook ([#3166](https://github.com/pybamm-team/PyBaMM/pull/3166))
- Thevenin() model is now constructed with standard variables: `Time [s]`, `Time [min]`, `Time [h]` ([#3143](https://github.com/pybamm-team/PyBaMM/pull/3143))
- Error generated when invalid parameter values are passed ([#3132](https://github.com/pybamm-team/PyBaMM/pull/3132))
- Parameters in `Prada2013` have been updated to better match those given in the paper, which is a 2.3 Ah cell, instead of the mix-and-match with the 1.1 Ah cell from Lain2019 ([#3096](https://github.com/pybamm-team/PyBaMM/pull/3096))



## Breaking changes

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118 changes: 92 additions & 26 deletions pybamm/simulation.py
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Expand Up @@ -648,6 +648,21 @@ def solve(
starting_solution.all_first_states.copy()
)

# set simulation initial_start_time
if starting_solution is None:
initial_start_time = self.experiment.initial_start_time
else:
initial_start_time = starting_solution.initial_start_time

if (
initial_start_time is None
and self.experiment.initial_start_time is not None
):
raise ValueError(
"When using experiments with `start_time`, the starting_solution "
"must have a `start_time` too."
)

cycle_offset = len(starting_solution_cycles)
all_cycle_solutions = starting_solution_cycles
all_summary_variables = starting_solution_summary_variables
Expand All @@ -660,6 +675,49 @@ def solve(
idx = 0
num_cycles = len(self.experiment.cycle_lengths)
feasible = True # simulation will stop if experiment is infeasible

# Add initial padding rest if current time is earlier than first start time
# This could be the case when using a starting solution
if starting_solution is not None:
op_conds = self.experiment.operating_conditions_steps[0]
if op_conds.start_time is not None:
rest_time = (
op_conds.start_time
- (
initial_start_time
+ timedelta(seconds=float(current_solution.t[-1]))
)
).total_seconds()
if rest_time > pybamm.settings.step_start_offset:
# logs["step operating conditions"] = "Initial rest for padding"
# callbacks.on_step_start(logs)

kwargs["inputs"] = {
**user_inputs,
"Ambient temperature [K]": (
op_conds.temperature or self._original_temperature
),
"start time": current_solution.t[-1],
}
steps = current_solution.cycles[-1].steps
step_solution = current_solution.cycles[-1].steps[-1]

step_solution_with_rest = self.run_padding_rest(
kwargs, rest_time, step_solution
)
steps[-1] = step_solution + step_solution_with_rest

cycle_solution, _, _ = pybamm.make_cycle_solution(
steps, esoh_solver=esoh_solver, save_this_cycle=True
)
old_cycles = current_solution.cycles.copy()
old_cycles[-1] = cycle_solution
current_solution += step_solution_with_rest
current_solution.cycles = old_cycles

# Update _solution
self._solution = current_solution

for cycle_num, cycle_length in enumerate(
# tqdm is the progress bar.
tqdm.tqdm(
Expand All @@ -683,6 +741,8 @@ def solve(
save_this_cycle = (
# always save cycle 1
cycle_num == 1
# always save last cycle
or cycle_num == num_cycles
# None: save all cycles
or save_at_cycles is None
# list: save all cycles in the list
Expand Down Expand Up @@ -710,7 +770,7 @@ def solve(
(
op_conds.end_time
- (
self.experiment.initial_start_time
initial_start_time
+ timedelta(seconds=float(start_time))
)
).total_seconds(),
Expand Down Expand Up @@ -765,41 +825,25 @@ def solve(
rest_time = (
op_conds.next_start_time
- (
self.experiment.initial_start_time
initial_start_time
+ timedelta(seconds=float(step_solution.t[-1]))
)
).total_seconds()
if rest_time > pybamm.settings.step_start_offset:
start_time = step_solution.t[-1]
# Let me know if you have a better name
op_conds_str = "Rest for padding"
model = self.op_conds_to_built_models[op_conds_str]
solver = self.op_conds_to_built_solvers[op_conds_str]

logs["step number"] = (step_num, cycle_length)
logs["step operating conditions"] = op_conds_str
logs["step operating conditions"] = "Rest for padding"
callbacks.on_step_start(logs)

ambient_temp = (
op_conds.temperature or self._original_temperature
)
kwargs["inputs"] = {
**user_inputs,
"Ambient temperature [K]": ambient_temp,
"start time": start_time,
"Ambient temperature [K]": (
op_conds.temperature or self._original_temperature
),
"start time": step_solution.t[-1],
}
# Make sure we take at least 2 timesteps
# The period is hardcoded to 10 minutes, the user can
# always override it by adding a rest step
npts = max(int(round(rest_time / 600)) + 1, 2)

step_solution_with_rest = solver.step(
step_solution,
model,
rest_time,
npts=npts,
save=False,
**kwargs,

step_solution_with_rest = self.run_padding_rest(
kwargs, rest_time, step_solution
)
step_solution += step_solution_with_rest

Expand Down Expand Up @@ -903,8 +947,30 @@ def solve(

callbacks.on_experiment_end(logs)

# record initial_start_time of the solution
self.solution.initial_start_time = initial_start_time

return self.solution

def run_padding_rest(self, kwargs, rest_time, step_solution):
model = self.op_conds_to_built_models["Rest for padding"]
solver = self.op_conds_to_built_solvers["Rest for padding"]

# Make sure we take at least 2 timesteps. The period is hardcoded to 10
# minutes,the user can always override it by adding a rest step
npts = max(int(round(rest_time / 600)) + 1, 2)

step_solution_with_rest = solver.step(
step_solution,
model,
rest_time,
npts=npts,
save=False,
**kwargs,
)

return step_solution_with_rest

def step(
self, dt, solver=None, npts=2, save=True, starting_solution=None, **kwargs
):
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12 changes: 12 additions & 0 deletions pybamm/solvers/solution.py
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Original file line number Diff line number Diff line change
Expand Up @@ -131,6 +131,9 @@ def __init__(
# Initialize empty summary variables
self._summary_variables = None

# Initialise initial start time
self.initial_start_time = None

# Solution now uses CasADi
pybamm.citations.register("Andersson2019")

Expand Down Expand Up @@ -434,6 +437,15 @@ def cycles(self, cycles):
def summary_variables(self):
return self._summary_variables

@property
def initial_start_time(self):
return self._initial_start_time

@initial_start_time.setter
def initial_start_time(self, value):
"""Updates the reason for termination"""
self._initial_start_time = value

def set_summary_variables(self, all_summary_variables):
summary_variables = {var: [] for var in all_summary_variables[0]}
for sum_vars in all_summary_variables:
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95 changes: 92 additions & 3 deletions tests/unit/test_experiments/test_simulation_with_experiment.py
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Original file line number Diff line number Diff line change
Expand Up @@ -382,9 +382,9 @@ def test_save_at_cycles(self):
solver=pybamm.CasadiSolver("fast with events"), save_at_cycles=[3, 4, 5, 9]
)
# Note offset by 1 (0th cycle is cycle 1)
for cycle_num in [1, 5, 6, 7, 9]:
for cycle_num in [1, 5, 6, 7]:
self.assertIsNone(sol.cycles[cycle_num])
for cycle_num in [0, 2, 3, 4, 8]:
for cycle_num in [0, 2, 3, 4, 8, 9]: # first & last cycle always saved
self.assertIsNotNone(sol.cycles[cycle_num])
# Summary variables are not None
self.assertIsNotNone(sol.summary_variables["Capacity [A.h]"])
Expand Down Expand Up @@ -605,7 +605,7 @@ def test_padding_rest_model(self):
pybamm.lithium_ion.SPM,
)

def test_run_time_stamped_experiment(self):
def test_run_start_time_experiment(self):
model = pybamm.lithium_ion.SPM()

# Test experiment is cut short if next_start_time is early
Expand Down Expand Up @@ -640,6 +640,95 @@ def test_run_time_stamped_experiment(self):
sol = sim.solve(calc_esoh=False)
self.assertEqual(sol["Time [s]"].entries[-1], 10800)

def test_starting_solution(self):
model = pybamm.lithium_ion.SPM()

experiment = pybamm.Experiment(
[
pybamm.step.string("Discharge at C/2 for 10 minutes"),
pybamm.step.string("Rest for 5 minutes"),
pybamm.step.string("Rest for 5 minutes"),
]
)

sim = pybamm.Simulation(model, experiment=experiment)
solution = sim.solve(save_at_cycles=[1])

# test that the last state is correct (i.e. final cycle is saved)
self.assertEqual(solution.last_state.t[-1], 1200)

experiment = pybamm.Experiment(
[
pybamm.step.string("Discharge at C/2 for 20 minutes"),
pybamm.step.string("Rest for 20 minutes"),
]
)

sim = pybamm.Simulation(model, experiment=experiment)
new_solution = sim.solve(calc_esoh=False, starting_solution=solution)

# test that the final time is correct (i.e. starting solution correctly set)
self.assertEqual(new_solution["Time [s]"].entries[-1], 3600)

def test_experiment_start_time_starting_solution(self):
model = pybamm.lithium_ion.SPM()

# Test error raised if starting_solution does not have start_time
experiment = pybamm.Experiment(
[pybamm.step.string("Discharge at C/2 for 10 minutes")]
)
sim = pybamm.Simulation(model, experiment=experiment)
solution = sim.solve()

experiment = pybamm.Experiment(
[
pybamm.step.string(
"Discharge at C/2 for 10 minutes",
start_time=datetime(1, 1, 1, 9, 0, 0),
)
]
)

sim = pybamm.Simulation(model, experiment=experiment)
with self.assertRaisesRegex(ValueError, "experiments with `start_time`"):
sim.solve(starting_solution=solution)

# Test starting_solution works well with start_time
experiment = pybamm.Experiment(
[
pybamm.step.string(
"Discharge at C/2 for 10 minutes",
start_time=datetime(1, 1, 1, 8, 0, 0),
),
pybamm.step.string(
"Discharge at C/2 for 10 minutes",
start_time=datetime(1, 1, 1, 8, 20, 0),
),
]
)

sim = pybamm.Simulation(model, experiment=experiment)
solution = sim.solve()

experiment = pybamm.Experiment(
[
pybamm.step.string(
"Discharge at C/2 for 10 minutes",
start_time=datetime(1, 1, 1, 9, 0, 0),
),
pybamm.step.string(
"Discharge at C/2 for 10 minutes",
start_time=datetime(1, 1, 1, 9, 20, 0),
),
]
)

sim = pybamm.Simulation(model, experiment=experiment)
new_solution = sim.solve(starting_solution=solution)

# test that the final time is correct (i.e. starting solution correctly set)
self.assertEqual(new_solution["Time [s]"].entries[-1], 5400)


if __name__ == "__main__":
print("Add -v for more debug output")
Expand Down

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