Add capacity/availability constraints

Closes #579.

Author: alexdewar

src/simulation/optimisation/constraints.rs

@@ -67,7 +67,7 @@ pub fn add_asset_constraints(
         add_commodity_balance_constraints(problem, variables, model, assets, year);
 
     let capacity_keys =
-        add_asset_capacity_constraints(problem, variables, assets, &model.time_slice_info);
+        add_asset_capacity_constraints(problem, variables, &model.time_slice_info, assets);
 
     // Return constraint keys
     ConstraintKeys {
@@ -103,26 +103,27 @@ fn add_commodity_balance_constraints(
 
 /// Add asset-level capacity and availability constraints.
 ///
-/// For every asset at every time slice, the sum of the commodity flows for assets must not exceed
-/// the capacity limits, which are a product of the annual capacity, time slice length and process
-/// availability.
-///
-/// See description in [the dispatch optimisation documentation][1].
-///
-/// [1]: https://energysystemsmodellinglab.github.io/MUSE_2.0/dispatch_optimisation.html#asset-level-capacity-and-availability-constraints
+/// This ensures that assets do not exceed their specified capacity and availability for each time
+/// slice.
 fn add_asset_capacity_constraints(
     problem: &mut Problem,
-    _variables: &VariableMap,
-    _assets: &AssetPool,
-    _time_slice_info: &TimeSliceInfo,
+    variables: &VariableMap,
+    time_slice_info: &TimeSliceInfo,
+    assets: &AssetPool,
 ) -> CapacityKeys {
     // Row offset in problem. This line **must** come before we add more constraints.
     let offset = problem.num_rows();
 
-    let keys = Vec::new();
+    let mut keys = Vec::new();
+    for asset in assets.iter() {
+        for time_slice in time_slice_info.iter_ids() {
+            let var = variables.get(asset, time_slice);
+            let limits = asset.get_activity_limits(time_slice);
 
-    // **TODO:** Add capacity/availability constraints:
-    //  https://github.com/EnergySystemsModellingLab/MUSE_2.0/issues/579
+            problem.add_row(limits, [(var, 1.0)]);
+            keys.push((asset.clone(), time_slice.clone()))
+        }
+    }
 
     CapacityKeys { offset, keys }
 }