Changed the default number of units based on is_candidate.

src/constraints/constraint_units_available.jl

@@ -53,7 +53,9 @@ function _build_constraint_units_available(m, u, s, t)
             init=0,
         )
         <=
-        + number_of_units(m; unit=u, stochastic_scenario=s, t=t)
+        # Change the default number of units so that it is zero when candidate units are present
+        # and otherwise 1.
+        + ifelse(is_candidate(unit=u), 0, number_of_units(m; unit=u, stochastic_scenario=s, t=t) )
         - units_unavailable(m; unit=u, stochastic_scenario=s, t=t)
     )
 end

templates/spineopt_template.json

@@ -292,7 +292,7 @@
         ["unit", "is_renewable", false, "boolean_value_list", "Whether the unit is renewable - used in the minimum renewable generation constraint within the Benders master problem"],
         ["unit", "min_down_time", null, null, "Minimum downtime of a `unit` after it shuts down."],
         ["unit", "min_up_time", null, null, "Minimum uptime of a `unit` after it starts up."],
-        ["unit", "number_of_units", 1.0, null, "Denotes the number of 'sub units' aggregated to form the modelled `unit`."],
+        ["unit", "number_of_units", 1.0, null, "Denotes the number of 'sub units' aggregated to form the modelled `unit`. The default value becomes zero if `candidate_units` has been defined."],
         ["unit", "online_variable_type", "unit_online_variable_type_linear", "unit_online_variable_type_list", "A selector for how the `units_on` variable is represented within the model."],
         ["unit", "outage_variable_type", "unit_online_variable_type_none", "unit_online_variable_type_list", "Determines whether the outage variable is integer or continuous or none(no optimisation of maintenance outages)."],
         ["unit", "scheduled_outage_duration", null, null, "Specifies the amount of time a unit must be out of service for maintenance as a single block over the course of the optimisation window"],

test/constraints/constraint_unit.jl

@@ -124,6 +124,7 @@ function test_constraint_units_available()
     @testset "constraint_units_available" begin
         url_in = _test_constraint_unit_setup()
         number_of_units = 4
+        number_of_units_when_candidates_units = 0
         candidate_units = 3
         unit_availability_factor = 0.5
         object_parameter_values = [
@@ -147,7 +148,7 @@ function test_constraint_units_available()
             key = (unit(:unit_ab), s, t)
             var_u_on = var_units_on[key...]
             var_u_inv_av = var_units_invested_available[key...]
-            expected_con = @build_constraint(var_u_on <= number_of_units + var_u_inv_av)
+            expected_con = @build_constraint(var_u_on <= number_of_units_when_candidates_units + var_u_inv_av)
             con_key = (unit(:unit_ab), s, t)
             con = constraint[con_key...]
             observed_con = constraint_object(con)
@@ -160,6 +161,7 @@ function test_constraint_units_available_units_unavailable()
         url_in = _test_constraint_unit_setup()
         number_of_units = 4
         candidate_units = 3
+        number_of_units_when_candidates_units = ifelse(candidate_units == 0, number_of_units, 0) 
         units_unavailable = 1
         unit_availability_factor = 0.5
         object_parameter_values = [
@@ -184,7 +186,7 @@ function test_constraint_units_available_units_unavailable()
             key = (unit(:unit_ab), s, t)
             var_u_on = var_units_on[key...]
             var_u_inv_av = var_units_invested_available[key...]
-            expected_con = @build_constraint(var_u_on <= number_of_units + var_u_inv_av - units_unavailable)
+            expected_con = @build_constraint(var_u_on <= number_of_units_when_candidates_units + var_u_inv_av - units_unavailable)
             con_key = (unit(:unit_ab), s, t)
             con = constraint[con_key...]
             observed_con = constraint_object(con)