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Fix zero-sequence model of Yyn transformer #1197

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Fix zero-sequence model of Yyn transformer #1197

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dbe0af0
try to fix transformer yyn
TonyXiang8787 Nov 21, 2025
ff68cfb
fix YNyn
TonyXiang8787 Nov 21, 2025
58ff798
fix test
TonyXiang8787 Nov 21, 2025
3b632cd
add info to debug
TonyXiang8787 Nov 21, 2025
ee6bc78
add info to debug
TonyXiang8787 Nov 21, 2025
cf3d2a9
avoid exact zero division
TonyXiang8787 Nov 21, 2025
6507e44
add new validation case
TonyXiang8787 Nov 25, 2025
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38 changes: 28 additions & 10 deletions power_grid_model_c/power_grid_model/include/power_grid_model/component/transformer.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -213,7 +213,7 @@
auto const [y_series, y_shunt, k] = transformer_params();
return calc_param_y_sym(y_series, y_shunt, k * std::exp(1.0i * (clock_ * deg_30)));
}
BranchCalcParam<asymmetric_t> asym_calc_param() const final {

Check failure on line 216 in power_grid_model_c/power_grid_model/include/power_grid_model/component/transformer.hpp

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SonarQubeCloud / SonarCloud Code Analysis

Refactor this function to reduce its Cognitive Complexity from 29 to the 25 allowed. 


See more on https://sonarcloud.io/project/issues?id=PowerGridModel_power-grid-model&issues=AZqm09HrMkJTTJ2mAAjT&open=AZqm09HrMkJTTJ2mAAjT&pullRequest=1197
auto const [y_series, y_shunt, k] = transformer_params();
// positive sequence
auto const param1 = calc_param_y_sym(y_series, y_shunt, k * std::exp(1.0i * (clock_ * deg_30)));
Expand All @@ -232,17 +232,35 @@
DoubleComplex const y0_series = 1.0 / z0_series;
param0 = calc_param_y_sym(y0_series, y_shunt, k * std::exp(1.0i * phase_shift_0));
}
// YNd
if (winding_from_ == WindingType::wye_n && winding_to_ == WindingType::delta && from_status()) {
DoubleComplex const z0_series = 1.0 / y_series + 3.0 * z_grounding_from_ / k / k;
DoubleComplex const y0_series = 1.0 / z0_series;
param0.yff() = (y0_series + y_shunt) / k / k;
// YN*

Check warning on line 235 in power_grid_model_c/power_grid_model/include/power_grid_model/component/transformer.hpp

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SonarQubeCloud / SonarCloud Code Analysis

Remove the commented out code. 


See more on https://sonarcloud.io/project/issues?id=PowerGridModel_power-grid-model&issues=AZqmbydBdIPvaMuHcmjp&open=AZqmbydBdIPvaMuHcmjp&pullRequest=1197
else if (winding_from_ == WindingType::wye_n && from_status()) {
// ground path always possible via magnetization branch
DoubleComplex y0 = y_shunt;
if (winding_to_ == WindingType::delta) {
// additional path via zk
y0 += y_series;
}
if (y0 != DoubleComplex{0.0, 0.0}) {
// avoid division by zero
DoubleComplex const z0 = 1.0 / y0 + 3.0 * z_grounding_from_ / k / k;
y0 = 1.0 / z0;
param0.yff() = y0 / k / k;
}
}
// Dyn
if (winding_from_ == WindingType::delta && winding_to_ == WindingType::wye_n && to_status()) {
DoubleComplex const z0_series = 1.0 / y_series + 3.0 * z_grounding_to_;
DoubleComplex const y0_series = 1.0 / z0_series;
param0.ytt() = (y0_series + y_shunt);
// *yn
else if (winding_to_ == WindingType::wye_n && to_status()) {
// ground path always possible via magnetization branch
DoubleComplex y0 = y_shunt;
if (winding_from_ == WindingType::delta) {
// additional path via zk
y0 += y_series;
}
if (y0 != DoubleComplex{0.0, 0.0}) {
// avoid division by zero
DoubleComplex const z0 = 1.0 / y0 + 3.0 * z_grounding_to_;
y0 = 1.0 / z0;
param0.ytt() = y0;
}
}
// ZN*
// Zero sequence impedance of zigzag winding is approximately 10% of positive sequence impedance
Expand Down
4 changes: 2 additions & 2 deletions tests/cpp_unit_tests/test_transformer.cpp
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Expand Up @@ -485,7 +485,7 @@ TEST_CASE("Test Transfomer - Test grounding - Dyn11") {
DoubleComplex const y_0_ff = low_admittance;
DoubleComplex const y_0_ft = 0.0;
DoubleComplex const y_0_tf = 0.0;
DoubleComplex const y_0_tt = (1.0 / (z_1_series + 3.0 * z_grounding_to)) + y_1_shunt;
DoubleComplex const y_0_tt = (1.0 / (1.0 / (1.0 / z_1_series + y_1_shunt) + 3.0 * z_grounding_to));

// Sequence admittances -> phase addmitance
ComplexTensor<asymmetric_t> y_ff_diagonal;
Expand Down Expand Up @@ -707,7 +707,7 @@ TEST_CASE("Test Transformer - Dyn11 - tap_max and tap_min flipped") {
DoubleComplex const y_0_ff = low_admittance;
DoubleComplex const y_0_ft = 0.0;
DoubleComplex const y_0_tf = 0.0;
DoubleComplex const y_0_tt = (1.0 / (z_1_series + 3.0 * z_grounding_to)) + y_1_shunt;
DoubleComplex const y_0_tt = (1.0 / (1.0 / (1.0 / z_1_series + y_1_shunt) + 3.0 * z_grounding_to));

// Sequence admittances -> phase addmitance
ComplexTensor<asymmetric_t> y_ff_diagonal;
Expand Down
21 changes: 21 additions & 0 deletions tests/data/power_flow/zero_sequence_yyn_transformer/asym_output.json
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@@ -0,0 +1,21 @@
{
"version": "1.0",
"type": "asym_output",
"is_batch": false,
"attributes": {},
"data": {
"node": [
{"id": 1, "energized": 1, "u_pu": [1, 1, 1], "u": [5773.5026918962576, 5773.5026918962576, 5773.5026918962576], "u_angle": [-2.474640575439679e-44, -2.0943951023931953, 2.0943951023931953], "p": [824880.19181322691, 1072224.8788595221, 1102894.9293272516], "q": [218912.27669635782, 40693.031260342112, 344009.43645155017]},
{"id": 2, "energized": 1, "u_pu": [1.1450055302608289, 0.94457144911056157, 0.91924181371456271], "u": [6610.6925111969977, 5453.4858041281759, 5307.2450859846258], "u_angle": [-0.03356887190092963, -1.984902584683417, 1.9252028204298137], "p": [-949999.9999999979, -1000000.0000000031, -1049999.9999999963], "q": [1.6449686064130695e-08, -3.0224494451098491e-09, 3.984667595393038e-09]}
],
"transformer": [
{"id": 4, "energized": 1, "loading": 0.30817316848870924, "p_from": [824880.19181322691, 1072224.8788595221, 1102894.9293272516], "q_from": [218912.27669635782, 40693.031260342126, 344009.43645155017], "i_from": [147.81913770559706, 185.84849584851148, 200.10395179782012], "s_from": [853434.18945704808, 1072996.791066251, 1155300.7043637931], "p_to": [-949999.9999999979, -1000000.0000000031, -1049999.9999999963], "q_to": [1.644994521118116e-08, -2.9986559036607486e-09, 3.9875615770433002e-09], "i_to": [143.70657815212488, 183.36895628169123, 197.84275702149816], "s_to": [949999.9999999979, 1000000.0000000031, 1049999.9999999963]}
],
"asym_load": [
{"id": 6, "energized": 1, "p": [950000, 1000000, 1050000], "q": [0, 0, 0], "i": [143.70657815212516, 183.36895628169069, 197.84275702149884], "s": [950000, 1000000, 1050000], "pf": [1, 1, 1]}
],
"source": [
{"id": 7, "energized": 1, "p": [824880.19181322691, 1072224.8788595221, 1102894.9293272516], "q": [218912.27669635782, 40693.031260342126, 344009.43645155017], "i": [147.81913770559706, 185.84849584851148, 200.10395179782012], "s": [853434.18945704808, 1072996.791066251, 1155300.7043637931], "pf": [0.96654223840975118, 0.99928060157014831, 0.9546388443817313]}
]
}
}
3 changes: 3 additions & 0 deletions tests/data/power_flow/zero_sequence_yyn_transformer/asym_output.json.license
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@@ -0,0 +1,3 @@
SPDX-FileCopyrightText: Contributors to the Power Grid Model project <powergridmodel@lfenergy.org>

SPDX-License-Identifier: MPL-2.0
21 changes: 21 additions & 0 deletions tests/data/power_flow/zero_sequence_yyn_transformer/input.json
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{
"version": "1.0",
"type": "input",
"is_batch": false,
"attributes": {},
"data": {
"node": [
{"id": 1, "u_rated": 10000},
{"id": 2, "u_rated": 10000}
],
"transformer": [
{"id": 4, "from_node": 1, "to_node": 2, "from_status": 1, "to_status": 1, "u1": 10000, "u2": 10000, "sn": 10000000, "uk": 0.10000000000000001, "pk": 0, "i0": 0.050000000000000003, "p0": 0, "winding_from": 0, "winding_to": 1, "clock": 12, "tap_side": 0, "tap_pos": 0, "tap_min": 0, "tap_max": 0, "tap_nom": 0, "tap_size": 0}
],
"asym_load": [
{"id": 6, "node": 2, "status": 1, "type": 0, "p_specified": [950000, 1000000, 1050000], "q_specified": [0, 0, 0]}
],
"source": [
{"id": 7, "node": 1, "status": 1, "u_ref": 1, "sk": 1.0000000000000001e+50, "rx_ratio": 0, "z01_ratio": 1}
]
}
}
3 changes: 3 additions & 0 deletions tests/data/power_flow/zero_sequence_yyn_transformer/input.json.license
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SPDX-FileCopyrightText: Contributors to the Power Grid Model project <powergridmodel@lfenergy.org>

SPDX-License-Identifier: MPL-2.0
7 changes: 7 additions & 0 deletions tests/data/power_flow/zero_sequence_yyn_transformer/params.json
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@@ -0,0 +1,7 @@
{
"calculation_method": [
"newton_raphson"
],
"rtol": 1e-07,
"atol": 1e-07
}
3 changes: 3 additions & 0 deletions tests/data/power_flow/zero_sequence_yyn_transformer/params.json.license
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SPDX-FileCopyrightText: Contributors to the Power Grid Model project <powergridmodel@lfenergy.org>

SPDX-License-Identifier: MPL-2.0
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