Add transformer tap setting correction to match PSSE

src/definitions.jl

@@ -181,6 +181,7 @@ const BRANCH_BUS_VOLTAGE_DIFFERENCE_TOL = 0.01
 
 const PSSE_PARSER_TAP_RATIO_UBOUND = 1.5
 const PSSE_PARSER_TAP_RATIO_LBOUND = 0.5
+const PARSER_TAP_RATIO_CORRECTION_TOL = 1e-5
 
 const WINDING_NAMES = Dict(
     WindingCategory.PRIMARY_WINDING => "primary",

src/parsers/pm_io/psse.jl

@@ -574,6 +574,37 @@ function _psse2pm_shunt!(pm_data::Dict, pti_data::Dict, import_all::Bool)
     end
 end
 
+function apply_tap_correction!(
+    windv_value::Float64,
+    transformer::Dict{String, Any},
+    cod_key::String,
+    rmi_key::String,
+    rma_key::String,
+    ntp_key::String,
+    cw_value::Int64,
+    winding_name::String,
+)
+    if abs(transformer[cod_key]) ∈ [1, 2] && cw_value ∈ [1, 3]
+        tap_positions = collect(
+            range(
+                transformer[rmi_key],
+                transformer[rma_key];
+                length = Int(transformer[ntp_key]),
+            ),
+        )
+        closest_tap_ix = argmin(abs.(tap_positions .- windv_value))
+        if !isapprox(
+            windv_value,
+            tap_positions[closest_tap_ix];
+            atol = PARSER_TAP_RATIO_CORRECTION_TOL,
+        )
+            @warn "Transformer $winding_name winding tap setting is not on a step; $windv_value set to $(tap_positions[closest_tap_ix])"
+            return tap_positions[closest_tap_ix]
+        end
+    end
+    return windv_value
+end
+
 """
     _psse2pm_transformer!(pm_data, pti_data)
 
@@ -769,10 +800,20 @@ function _psse2pm_transformer!(pm_data::Dict, pti_data::Dict, import_all::Bool)
                     sub_data["nomv2"] = transformer["NOMV2"]
                 end
 
-                sub_data["tap"] = pop!(transformer, "WINDV1") / pop!(transformer, "WINDV2")
+                windv1 = pop!(transformer, "WINDV1")
+                windv1 = apply_tap_correction!(
+                    windv1,
+                    transformer,
+                    "COD1",
+                    "RMI1",
+                    "RMA1",
+                    "NTP1",
+                    transformer["CW"],
+                    "primary",
+                )
+                sub_data["tap"] = windv1 / pop!(transformer, "WINDV2")
                 sub_data["shift"] = pop!(transformer, "ANG1")
 
-                # Unit Transformations
                 if transformer["CW"] != 1  # NOT "for off-nominal turns ratio in pu of winding bus base voltage"
                     sub_data["tap"] *=
                         _get_bus_value(transformer["J"], "base_kv", pm_data) /
@@ -1082,10 +1123,45 @@ function _psse2pm_transformer!(pm_data::Dict, pti_data::Dict, import_all::Bool)
                 sub_data["secondary_correction_table"] = transformer["TAB2"]
                 sub_data["tertiary_correction_table"] = transformer["TAB3"]
 
+                windv1 = transformer["WINDV1"]
+                windv2 = transformer["WINDV2"]
+                windv3 = transformer["WINDV3"]
+
+                windv1 = apply_tap_correction!(
+                    windv1,
+                    transformer,
+                    "COD1",
+                    "RMI1",
+                    "RMA1",
+                    "NTP1",
+                    transformer["CW"],
+                    "primary",
+                )
+                windv2 = apply_tap_correction!(
+                    windv2,
+                    transformer,
+                    "COD2",
+                    "RMI2",
+                    "RMA2",
+                    "NTP2",
+                    transformer["CW"],
+                    "secondary",
+                )
+                windv3 = apply_tap_correction!(
+                    windv3,
+                    transformer,
+                    "COD3",
+                    "RMI3",
+                    "RMA3",
+                    "NTP3",
+                    transformer["CW"],
+                    "tertiary",
+                )
+
                 if transformer["CW"] == 1
-                    sub_data["primary_turns_ratio"] = transformer["WINDV1"]
-                    sub_data["secondary_turns_ratio"] = transformer["WINDV2"]
-                    sub_data["tertiary_turns_ratio"] = transformer["WINDV3"]
+                    sub_data["primary_turns_ratio"] = windv1
+                    sub_data["secondary_turns_ratio"] = windv2
+                    sub_data["tertiary_turns_ratio"] = windv3
                 else
                     sub_data["primary_turns_ratio"] =
                         transformer["WINDV1"] / sub_data["base_voltage_primary"]

test/test_parse_psse.jl

@@ -353,6 +353,27 @@ end
     @test IS.compare_values(original_sys, deserialized_sys)
 end
 
+@testset "PSSE transformer tap position correction testing" begin
+    sys = build_system(
+        PSSEParsingTestSystems,
+        "psse_14_tap_correction_test_system";
+        force_build = true,
+    )
+    #test 2W correction matches PSSE
+    trf = get_component(TapTransformer, sys, "BUS 104-BUS 107-i_1")
+    tap = get_tap(trf)
+    @test isapprox(tap, 0.979937; atol = 1e-6)
+
+    #test 3W correction matches PSSE
+    trf_3w = get_component(Transformer3W, sys, "BUS 109-BUS 104-BUS 107-i_1")
+    tap1 = get_primary_turns_ratio(trf_3w)
+    tap2 = get_secondary_turns_ratio(trf_3w)
+    tap3 = get_tertiary_turns_ratio(trf_3w)
+    @test isapprox(tap1, 0.98750; atol = 1e-6)
+    @test isapprox(tap2, 0.97500; atol = 1e-6)
+    @test isapprox(tap3, 0.96250; atol = 1e-6)
+end
+
 @testset "PSSE isolated bus handling (unavailable vs topologically isolated)" begin
     sys =
         build_system(PSSEParsingTestSystems, "isolated_bus_test_system"; force_build = true)