Fixing Pumped Hydro formulation

src/core/variables.jl

@@ -33,7 +33,7 @@ Docs abbreviation: ``E^{surplus}``
 """
 struct HydroEnergySurplusVariable <: PSI.VariableType end
 
-# convert_result_to_natural_units(::Type{WaterSpillageVariable }) = true # TODO: is this pu?
+# convert_result_to_natural_units(::Type{HydroEnergyVariableUp}) = true # TODO: is this pu?
 
 """
 Auxiliary Variable for Hydro Models that solve for total energy output

src/hydro_generation.jl

@@ -597,6 +597,7 @@ function PSI.add_constraints!(
                 (spillage_var[name, 1] + powerout_var[name, 1]) / efficiency
             ) * fraction_of_hour +
             PSI.get_parameter_column_refs(param_container, name)[1] * multiplier[name, 1]
+            # Be consistent on this parameter definition
         )
 
         for t in time_steps[2:end]
@@ -607,7 +608,7 @@ function PSI.add_constraints!(
                 PSI.get_parameter_column_refs(param_container, name)[t] *
                 multiplier[name, t] +
                 (
-                    powerin_var[name, 1] -
+                    powerin_var[name, t] -
                     (powerout_var[name, t] + spillage_var[name, t]) / efficiency
                 ) * fraction_of_hour
             )

test/test_hydro_simulations.jl

@@ -1,3 +1,35 @@
+@testset "Single-stage Hydro Pumped Simulation" begin
+    output_dir = mktempdir(; cleanup=true)
+    sys_ed = PSB.build_system(PSITestSystems, "c_sys5_phes_ed")
+
+    template_ed = ProblemTemplate(CopperPlatePowerModel)
+    set_device_model!(template_ed, PowerLoad, StaticPowerLoad)
+    set_device_model!(template_ed, ThermalStandard, ThermalBasicUnitCommitment)
+    set_device_model!(template_ed, HydroPumpedStorage, HydroDispatchPumpedStorage)
+
+    model = DecisionModel(
+        template_ed,
+        sys_ed,
+        name="ED",
+        optimizer=HiGHS_optimizer,
+        optimizer_solve_log_print=true,
+        store_variable_names=true,
+    )
+
+    @test build!(model, output_dir=output_dir) == PSI.BuildStatus.BUILT
+    @test solve!(model; optimizer=HiGHS_optimizer, output_dir=output_dir) ==
+          RunStatus.SUCCESSFUL
+
+    results = ProblemResults(model)
+    variables = read_variables(results)
+
+    # Assert that the water level of the up reservoir level is zero at
+    # the last simulation step.
+    reservoir_up_level = "HydroEnergyVariableUp__HydroPumpedStorage"
+    last_value = last(variables[reservoir_up_level])["HydroPumpedStorage"]
+    @test isapprox(last_value, 0, atol=1e-5)
+end
+
 @testset "Multi-Stage Hydro Simulation Build" begin
     sys_md = PSB.build_system(PSISystems, "5_bus_hydro_wk_sys")