multiple sources at one bus and no other devices (#11)

* multiple sources at one bus and no other devices

* add test for only sources

src/post_processing.jl

@@ -176,6 +176,16 @@ function _power_redistribution_ref(
         P_gen -= sum(PSY.get_active_power.(sources))
         devices_ = setdiff(devices_, sources)
         @warn "Found sources and non-source devices at the same bus. Active power re-distribution is not well defined for this case. Source active power will remain unchanged and remaining active power will be re-distributed among non-source devices."
+    elseif length(sources) > 1 && length(non_source_devices) == 0
+        Psources = sum(PSY.get_active_power.(sources))
+        Qsources = sum(PSY.get_reactive_power.(sources))
+        if isapprox(Psources, P_gen; atol=0.001) && isapprox(Qsources, Q_gen; atol=0.001)
+            @warn "Only sources found at reference bus --- no redistribution of active or reactive power will take place"
+            return
+        else
+            @warn "Total source P: $(Psources), Total source Q:$(Qsources) Bus P:$(P_gen), Bus Q:$(Q_gen)"
+            error("Sources do not match P and/or Q requirements for reference bus.")
+        end
     end
     if length(devices_) == 1
         device = first(devices_)
@@ -268,6 +278,15 @@ function _reactive_power_redistribution_pv(sys::PSY.System, Q_gen::Float64, bus:
         Q_gen -= sum(PSY.get_reactive_power.(sources))
         devices_ = setdiff(devices_, sources)
         @warn "Found sources and non-source devices at the same bus. Reactive power re-distribution is not well defined for this case. Source reactive power will remain unchanged and remaining reactive power will be re-distributed among non-source devices."
+    elseif length(sources) > 1 && length(non_source_devices) == 0
+        Qsources = sum(PSY.get_active_power.(sources))
+        if isapprox(Qsources, Q_gen; atol=0.001)
+            @warn "Only sources found at PV bus --- no redistribution of reactive power will take place"
+            return
+        else
+            @warn "Total source Q:$(Qsources), Bus Q:$(Q_gen)"
+            error("Sources do not match Q requirements for PV bus.")
+        end
     end
     if length(devices_) == 1
         @debug "Only one generator in the bus"

test/test_powerflow_with_sources.jl

@@ -0,0 +1,42 @@
+@testset "Powerflow with multiple sources at bus" begin
+    sys = System(100.0)
+    b = Bus(
+        number=1,
+        name="01",
+        bustype=BusTypes.REF,
+        angle=0.0,
+        magnitude=1.1,
+        voltage_limits=(0.0, 2.0),
+        base_voltage=230,
+    )
+    add_component!(sys, b)
+
+    #Test two sources with equal and opposite P and Q
+    s1 = Source(
+        name="source_1",
+        available=true,
+        bus=b,
+        active_power=0.5,
+        reactive_power=0.1,
+        R_th=1e-5,
+        X_th=1e-5,
+    )
+    add_component!(sys, s1)
+    s2 = Source(
+        name="source_2",
+        available=true,
+        bus=b,
+        active_power=-0.5,
+        reactive_power=-0.1,
+        R_th=1e-5,
+        X_th=1e-5,
+    )
+    add_component!(sys, s2)
+    @test run_powerflow!(sys, finite_diff=true)
+
+    #Create power mismatch, test for error 
+    set_active_power!(get_component(Source, sys, "source_1"), -0.4)
+    @test_throws ErrorException(
+        "Sources do not match P and/or Q requirements for reference bus.",
+    ) run_powerflow!(sys, finite_diff=true)
+end