Route every start value through set_start_value!

src/InfrastructureOptimizationModels.jl

@@ -518,6 +518,7 @@ export AbstractOptimizationProblem
 # Settings and Data Types
 export Settings
 export get_warm_start
+export set_start_value!
 export get_horizon, get_initial_time, get_optimizer, get_ext, get_interval
 export get_check_components, get_initialize_model, get_initialization_file
 export get_deserialize_initial_conditions, get_export_pwl_vars

src/common_models/add_variable.jl

@@ -1,3 +1,23 @@
+"""
+Set `value` as the start value of `variable` when warm start is enabled in the container
+settings. A `nothing` value leaves the variable without a start value.
+
+Every start value in a model built on this package should go through this function, so a
+model built with `warm_start = false` reaches the solver with no start values at all. Some
+solvers treat a partial start as a sub-problem to complete before presolve, so a single
+stray start value can cost as much as a full warm start.
+"""
+function set_start_value!(
+    container::OptimizationContainer,
+    variable::JuMP.VariableRef,
+    value::Union{Nothing, Real},
+)
+    value === nothing && return
+    get_warm_start(get_settings(container)) || return
+    JuMP.set_start_value(variable, value)
+    return
+end
+
 @doc raw"""
 Adds a variable to the optimization model and to the affine expressions contained
 in the optimization_container model according to the specified sign. Based on the inputs, the variable can
@@ -43,18 +63,18 @@ function add_variables!(
 } where {D <: IS.InfrastructureSystemsComponent}
     @assert !isempty(devices)
     time_steps = get_time_steps(container)
-    settings = get_settings(container)
     binary = get_variable_binary(T, D, F)
+    included = [d for d in devices if !skip_variable(T, d, F)]
 
     variable = add_variable_container!(
         container,
         T,
         D,
-        get_name.(devices),
+        String[get_name(d) for d in included],
         time_steps,
     )
 
-    for t in time_steps, d in devices
+    for t in time_steps, d in included
         name = get_name(d)
         variable[name, t] = JuMP.@variable(
             get_jump_model(container),
@@ -67,10 +87,11 @@ function add_variables!(
         lb = get_variable_lower_bound(T, d, F)
         lb !== nothing && JuMP.set_lower_bound(variable[name, t], lb)
 
-        if get_warm_start(settings)
-            init = get_variable_warm_start_value(T, d, F)
-            init !== nothing && JuMP.set_start_value(variable[name, t], init)
-        end
+        set_start_value!(
+            container,
+            variable[name, t],
+            get_variable_warm_start_value(T, d, F),
+        )
     end
 
     return
@@ -154,7 +175,6 @@ function _add_service_device_variables!(
     D <: IS.InfrastructureSystemsComponent,
     F <: AbstractServiceFormulation,
 }
-    settings = get_settings(container)
     binary = get_variable_binary(T, U, F)
     service_name = IS.get_name(service)
     jump_model = get_jump_model(container)
@@ -170,10 +190,7 @@ function _add_service_device_variables!(
         ub !== nothing && JuMP.set_upper_bound(var, ub)
         lb = get_variable_lower_bound(T, service, d, F)
         lb !== nothing && !binary && JuMP.set_lower_bound(var, lb)
-        if get_warm_start(settings)
-            init = get_variable_warm_start_value(T, d, F)
-            init !== nothing && JuMP.set_start_value(var, init)
-        end
+        set_start_value!(container, var, get_variable_warm_start_value(T, d, F))
     end
     return
 end

src/common_models/interfaces.jl

@@ -76,6 +76,12 @@ get_variable_upper_bound(
     ::Type{<:Union{AbstractDeviceFormulation, AbstractServiceFormulation}},
 ) = nothing
 
+"""
+Extension point: whether `add_variables!` creates no variable for this device. A skipped
+device is left off the variable container's axis.
+"""
+skip_variable(::Type{<:VariableType}, ::IS.InfrastructureSystemsComponent, ::Type) = false
+
 """
 Extension point: Get variable warm start value.
 """

test/InfrastructureOptimizationModelsTests.jl

@@ -137,6 +137,7 @@ function run_tests()
                     # TODO tests?
                     include(joinpath(TEST_DIR, "test_jump_utils.jl"))
                     include(joinpath(TEST_DIR, "test_pwl_methods.jl"))
+                    include(joinpath(TEST_DIR, "test_start_values.jl"))
                     include(joinpath(TEST_DIR, "test_ramp_constraints.jl"))
                     include(joinpath(TEST_DIR, "test_parameterized_range_constraints.jl"))
                     include(joinpath(TEST_DIR, "test_duration_constraints.jl"))

test/test_start_values.jl

@@ -0,0 +1,95 @@
+struct WarmStartTestVariable <: IOM.VariableType end
+
+IOM.get_variable_binary(
+    ::Type{WarmStartTestVariable},
+    ::Type{MockThermalGen},
+    ::Type{TestDeviceFormulation},
+) = false
+IOM.get_variable_warm_start_value(
+    ::Type{WarmStartTestVariable},
+    d::MockThermalGen,
+    ::Type{TestDeviceFormulation},
+) = d.active_power_limits.max
+
+struct SkippedTestVariable <: IOM.VariableType end
+
+IOM.get_variable_binary(
+    ::Type{SkippedTestVariable},
+    ::Type{MockThermalGen},
+    ::Type{TestDeviceFormulation},
+) = false
+IOM.skip_variable(
+    ::Type{SkippedTestVariable},
+    d::MockThermalGen,
+    ::Type{TestDeviceFormulation},
+) = d.must_run
+
+function _warm_start_container(warm_start::Bool)
+    sys = MockSystem(100.0)
+    settings = IOM.Settings(
+        sys;
+        horizon = Dates.Hour(2),
+        resolution = Dates.Hour(1),
+        warm_start = warm_start,
+    )
+    container = IOM.OptimizationContainer(sys, settings, JuMP.Model(), IS.Deterministic)
+    IOM.set_time_steps!(container, 1:2)
+    return container
+end
+
+@testset "Start values" begin
+    @testset "set_start_value! follows the warm_start setting" begin
+        for warm_start in (true, false)
+            container = _warm_start_container(warm_start)
+            var = JuMP.@variable(IOM.get_jump_model(container))
+            IOM.set_start_value!(container, var, 2.5)
+            @test JuMP.start_value(var) == (warm_start ? 2.5 : nothing)
+        end
+    end
+
+    @testset "set_start_value! with nothing sets no start value" begin
+        container = _warm_start_container(true)
+        var = JuMP.@variable(IOM.get_jump_model(container))
+        IOM.set_start_value!(container, var, nothing)
+        @test JuMP.start_value(var) === nothing
+    end
+
+    @testset "add_variables! applies the warm start hook only with warm_start" begin
+        devices = [make_mock_thermal("gen1"; limits = (min = 0.0, max = 40.0))]
+        for warm_start in (true, false)
+            container = _warm_start_container(warm_start)
+            IOM.add_variables!(
+                container,
+                WarmStartTestVariable,
+                devices,
+                TestDeviceFormulation,
+            )
+            var = IOM.get_variable(container, WarmStartTestVariable, MockThermalGen)
+            for t in 1:2
+                @test JuMP.start_value(var["gen1", t]) == (warm_start ? 40.0 : nothing)
+            end
+        end
+    end
+
+    @testset "add_variables! leaves skipped devices off the axis" begin
+        container = _warm_start_container(true)
+        devices = [
+            make_mock_thermal("committed"),
+            make_mock_thermal("must_run"; must_run = true),
+        ]
+        IOM.add_variables!(container, SkippedTestVariable, devices, TestDeviceFormulation)
+        var = IOM.get_variable(container, SkippedTestVariable, MockThermalGen)
+        @test axes(var)[1] == ["committed"]
+
+        container = _warm_start_container(true)
+        all_skipped = [make_mock_thermal("must_run"; must_run = true)]
+        IOM.add_variables!(
+            container,
+            SkippedTestVariable,
+            all_skipped,
+            TestDeviceFormulation,
+        )
+        var = IOM.get_variable(container, SkippedTestVariable, MockThermalGen)
+        @test isempty(axes(var)[1])
+    end
+end