Add electricity angle variables (#1185)

* Add variable electricity angle

* Add dc_opf condition

* Apply review suggestions

* Improve sql

Author: gnawin

src/create-model.jl

@@ -89,6 +89,7 @@ function create_model(
     @timeit to "add_flow_variables!" add_flow_variables!(connection, model, variables)
     @timeit to "add_investment_variables!" add_investment_variables!(model, variables)
     @timeit to "add_unit_commitment_variables!" add_unit_commitment_variables!(model, variables)
+    @timeit to "add_power_flow_variables!" add_power_flow_variables!(model, variables)
     @timeit to "add_storage_variables!" add_storage_variables!(connection, model, variables)
 
     @timeit to "add_expressions_to_constraints!" add_expressions_to_constraints!(

src/sql/create-variables.sql

@@ -45,6 +45,45 @@ drop sequence id
 create sequence id start 1
 ;
 
+create table var_electricity_angle as
+select
+    nextval('id') as id,
+    atr.asset,
+    atr.year,
+    atr.rep_period,
+    atr.time_block_start,
+    any_value(atr.time_block_end) as time_block_end,
+from
+    -- The angle resolution is the same as the time resolution of the asset
+    asset_time_resolution_rep_period as atr
+    -- We need to check if the asset has any connecting flows that are transport
+    -- We only get the assets that have outgoing flows OR incoming flows
+    -- With the condition that the flows are transport
+    left join flow on flow.from_asset = atr.asset
+    or flow.to_asset = atr.asset
+    -- After that we need to also check if the flows have dc_opf method
+    -- This is by joining the flow_milestone table
+    -- Here we use AND because we need to match flow_milestone with flow
+    left join flow_milestone on flow_milestone.from_asset = flow.from_asset
+    and flow_milestone.to_asset = flow.to_asset
+    and flow_milestone.milestone_year = atr.year
+where
+    flow.is_transport
+    and flow_milestone.dc_opf
+-- We may end up with duplicates because an asset can have both incoming and outgoing flows
+-- Or it can have multiple flows
+-- GROUP BY is used to remove duplicates
+-- Note SELECT only happens after the GROUP BY, so id is unique for each row.
+group by
+    atr.asset, atr.year, atr.rep_period, atr.time_block_start
+;
+
+drop sequence id
+;
+
+create sequence id start 1
+;
+
 create table var_is_charging as
 select
     nextval('id') as id,

src/variables/create.jl

@@ -10,6 +10,7 @@ function compute_variables_indices(connection)
         key => TulipaVariable(connection, "var_$key") for key in (
             :flow,
             :units_on,
+            :electricity_angle,
             :is_charging,
             :storage_level_rep_period,
             :storage_level_over_clustered_year,

src/variables/power-flow.jl

@@ -0,0 +1,20 @@
+export add_power_flow_variables!
+
+"""
+    add_power_flow_variables!(model, variables)
+
+Adds power flow variables to the optimization `model` based on the `:electricity_angle` indices.
+
+"""
+function add_power_flow_variables!(model, variables)
+    electricity_angle_indices = variables[:electricity_angle].indices
+
+    variables[:electricity_angle].container = [
+        @variable(
+            model,
+            base_name = "electricity_angle[$(row.asset),$(row.year),$(row.rep_period),$(row.time_block_start):$(row.time_block_end)]",
+        ) for row in electricity_angle_indices
+    ]
+
+    return
+end