Support "non-integer" delay for Connections

assets/examples/50_delayed_connections.iesopt.yaml

@@ -0,0 +1,44 @@
+config:
+  general:
+    version:
+      core: 2.4.0
+  optimization:
+    problem_type: LP
+    solver:
+      name: highs
+    snapshots:
+      count: 4
+      weights: 0.25
+  results:
+    enabled: true
+    memory_only: true
+
+carriers:
+  water: {}
+
+components:
+  upper:
+    type: Node
+    carrier: water
+  lower:
+    type: Node
+    carrier: water
+  river:
+    type: Connection
+    node_from: upper
+    node_to: lower
+    delay: 1 // 3
+  inflow:
+    type: Profile
+    carrier: water
+    node_to: upper
+    mode: create
+  outflow:
+    type: Profile
+    carrier: water
+    node_from: lower
+    value:
+      - 1.0
+      - 2.0
+      - 1.5
+      - 0.5

src/core/connection.jl

@@ -249,15 +249,6 @@ function _isvalid(connection::Connection)
             @critical "Setting <delay> for Connection currently requires equal Snapshot weights" connection =
                 connection.name
         end
-
-        for t in get_T(connection.model)
-            delay = access(connection.delay, t, Float64)
-            if !isinteger(delay / sw[1])
-                # TODO: This is a temporary solution, implement and remove this.
-                @critical "Setting <delay> for Connection currently requires integer delays (thought in Snapshots)" connection =
-                    connection.name
-            end
-        end
     end
 
     return true

src/core/connection/var_flow.jl

@@ -73,22 +73,35 @@ function _connection_var_flow!(connection::Connection)
         has_delay = !_isempty(connection.delay)
 
         @inbounds @simd for t in get_T(model)
-            t0 = t
-            if !has_delay
-                t1 = t
+            delayed_snapshots, delayed_weights = if !has_delay
+                (t,), (1.0,)
             else
-                t1 = (Int64(t + access(connection.delay, t)::Float64 / Δ) - 1) % get_T(model)[end] + 1
+                Δi, r = divrem(access(connection.delay, t), Δ)
+                mod1.(t .+ Int(Δi) .+ (0, 1), last(get_T(model))), (1 - r / Δ, r / Δ)
             end
-
-            if connection.loss_mode == :to
-                JuMP.add_to_expression!(connection.exp.in[t0], cvf[t0], 1.0)
-                JuMP.add_to_expression!(connection.exp.out[t1], cvf[t0], (1.0 - access(loss, t0)::Float64))
-            elseif connection.loss_mode == :from
-                JuMP.add_to_expression!(connection.exp.in[t0], cvf[t0], 1.0 / (1.0 - access(loss, t0)::Float64))
-                JuMP.add_to_expression!(connection.exp.out[t1], cvf[t0], 1.0)
-            elseif connection.loss_mode == :split
-                JuMP.add_to_expression!(connection.exp.in[t0], cvf[t0], 1.0 / sqrt(1.0 - access(loss, t0)::Float64))
-                JuMP.add_to_expression!(connection.exp.out[t1], cvf[t0], sqrt(1.0 - access(loss, t0)::Float64))
+            if connection.loss_mode === :to
+                JuMP.add_to_expression!(connection.exp.in[t], cvf[t], 1.0)
+                for (i, td) in enumerate(delayed_snapshots)
+                    JuMP.add_to_expression!(
+                        connection.exp.out[td],
+                        cvf[t],
+                        delayed_weights[i] * (1.0 - access(loss, t)::Float64),
+                    )
+                end
+            elseif connection.loss_mode === :from
+                JuMP.add_to_expression!(connection.exp.in[t], cvf[t], 1.0 / (1.0 - access(loss, t)::Float64))
+                for (i, td) in enumerate(delayed_snapshots)
+                    JuMP.add_to_expression!(connection.exp.out[td], cvf[t], delayed_weights[i])
+                end
+            elseif connection.loss_mode === :split
+                JuMP.add_to_expression!(connection.exp.in[t], cvf[t], 1.0 / sqrt(1.0 - access(loss, t)::Float64))
+                for (i, td) in enumerate(delayed_snapshots)
+                    JuMP.add_to_expression!(
+                        connection.exp.out[td],
+                        cvf[t],
+                        delayed_weights[i] * sqrt(1.0 - access(loss, t)::Float64),
+                    )
+                end
             end
         end
 

test/src/examples.jl

@@ -235,3 +235,17 @@ end
         ).input.files["data"],
     ) == (8760, 8)
 end
+
+@testitem "50_delayed_connections" tags = [:examples] setup = [TestExampleModule] begin
+    model = TestExampleModule.check(; obj=0.0)
+
+    river = internal(model).results.components["river"]
+    weight = 0.25
+    delay = 1 // 3
+    d, r = divrem(delay, weight)
+    for i in get_T(model)
+        first_inflow = r / weight * river.exp.in[mod1(i - Int(d) - 1, end)]
+        second_inflow = (1 - r / weight) * river.exp.in[mod1(i - Int(d), end)]
+        @test river.exp.out[i] == first_inflow + second_inflow
+    end
+end