fix cmin for low voltage 10% tolerance

pandapower/build_bus.py

@@ -1113,11 +1113,13 @@ def _add_c_to_ppc(net, ppc):
     if len(lv_buses) > 0:
         lv_tol_percent = net["_options"]["lv_tol_percent"]
         if lv_tol_percent == 10:
-            c_ns = 1.1
+            c_max = 1.1
+            c_min = 0.9
         elif lv_tol_percent == 6:
-            c_ns = 1.05
+            c_max = 1.05
+            c_min = 0.95
         else:
             raise ValueError("Voltage tolerance in the low voltage grid has" +
                              " to be either 6% or 10% according to IEC 60909")
-        ppc["bus"][lv_buses, C_MAX] = c_ns
-        ppc["bus"][lv_buses, C_MIN] = .95
+        ppc["bus"][lv_buses, C_MAX] = c_max
+        ppc["bus"][lv_buses, C_MIN] = c_min

pandapower/test/shortcircuit/test_meshing_detection.py

@@ -60,16 +60,16 @@ def test_min_10_meshed_grid(meshed_grid):
     net = meshed_grid
     calc_sc(net, case='min', ip=True, ith=True, lv_tol_percent=10., kappa_method="B")
     assert np.allclose(net.res_bus_sc.ikss_ka.values[:10],
-                       [2.309401, 11.3267, 2.879343, 1.884323, 10.40083,
-                        1.693922, 0.7107017, 0.9000445, 1.055881, 0.928488], atol=1e-5)
+                       [2.309401, 10.73055529, 2.72779866, 1.884323, 9.8534192,
+                        1.60476785, 0.67329634, 0.8526737, 1.00030861, 0.87962022], atol=1e-5)
 
     assert np.allclose(net.res_bus_sc.ip_ka.values[:10],
-                       [5.702418, 26.01655, 4.166047, 3.124163, 20.04053,
-                        2.813883, 1.179085, 1.493293, 1.523338, 1.540432], atol=1e-5)
+                       [5.702418, 24.64726031, 3.94678188, 3.124163, 18.98576367,
+                        2.66578429, 1.11702772, 1.41469836, 1.44316232, 1.45935648], atol=1e-5)
 
     assert np.allclose(net.res_bus_sc.ith_ka.values[:10],
-                       [2.348476, 11.44622, 2.883161, 1.889675, 10.45195,
-                        1.698768, 0.712725, 0.9026074, 1.057233, 0.9311316], atol=1e-5)
+                       [2.348476, 10.84378991, 2.73141581, 1.889675, 9.90184777,
+                        1.60935911, 0.67521318, 0.85510173, 1.00158882, 0.88212465], atol=1e-5)
 
 
 def test_min_6_meshed_grid(meshed_grid):

pandapower/test/shortcircuit/test_motor.py

@@ -37,7 +37,7 @@ def test_motor_min(motor_net):
     net = motor_net
     calc_sc(net, case="min")
     assert np.allclose(net.res_bus_sc.ikss_ka.values[:3],
-                       [11.547005315, 0.53709235574, 0.18070949061], rtol=1e-4)
+                       [11.54700538, 0.50921396, 0.17123864], rtol=1e-4)
 
 
 def test_motor_max(motor_net):

pandapower/test/shortcircuit/test_sc_single_bus.py

@@ -10,6 +10,7 @@
     create_sgen
 from pandapower.shortcircuit.calc_sc import calc_sc
 from pandapower.test.shortcircuit.test_meshing_detection import meshed_grid
+from pandapower.create import create_impedance
 
 
 # @pytest.fixture
@@ -98,6 +99,27 @@ def test_big_gen_network_calc_sc():
         assert np.isclose(net.res_line_sc.ikss_ka.at[0], 0.46221808, atol=1e-3)
         assert np.isclose(net.res_line_sc.ikss_ka.at[1], 1.72233192, atol=1e-3)
 
+def test_iec60909_on_single_branch():
+    cases = {
+        10: {
+            "min": [72.16878364, 49.868725],
+            "max": [144.337567, 81.818773]
+        },
+        6: {
+            "min": [72.168784,    50.761055],
+            "max": [144.337567,     80.016087]
+        }
+    }
+    for tolerance in cases.keys():
+        for case in cases[tolerance].keys():
+            net = create_empty_network()
+            b1 = create_bus(net, vn_kv=0.4)
+            b2 = create_bus(net, vn_kv=0.4)
+            create_ext_grid(net, b1, s_sc_max_mva=100., s_sc_min_mva=50., rx_min=1, rx_max=1)
+            create_impedance(net, b1, b2, 0.01, 0, 1)
+            calc_sc(net, case=case, lv_tol_percent=tolerance)
+            assert np.allclose(net.res_bus_sc.ikss_ka, cases[tolerance][case], atol=1e-3)
+
 
 if __name__ == '__main__':
     pytest.main([__file__, "-xs"])

pandapower/test/shortcircuit/test_transformer.py

@@ -66,15 +66,15 @@ def test_min_10_trafo(net_transformer):
     calc_sc(net, case='min', ip=True, ith=True, lv_tol_percent=10.)
     assert (abs(net.res_bus_sc.ikss_ka.at[0] - 2.309401) < 1e-5)
     assert (abs(net.res_bus_sc.ikss_ka.at[1] - 2.309401) < 1e-5)
-    assert (abs(net.res_bus_sc.ikss_ka.at[2] - 12.912468695) < 1e-5)
+    assert (abs(net.res_bus_sc.ikss_ka.at[2] - 12.23286384) < 1e-5)
 
     assert (abs(net.res_bus_sc.ip_ka.at[0] - 5.702418) < 1e-5)
     assert (abs(net.res_bus_sc.ip_ka.at[1] - 5.702418) < 1e-5)
-    assert (abs(net.res_bus_sc.ip_ka.at[2] - 32.405489528) < 1e-5)
+    assert (abs(net.res_bus_sc.ip_ka.at[2] - 30.6999346054) < 1e-5)
 
     assert (abs(net.res_bus_sc.ith_ka.at[0] - 2.348476) < 1e-5)
     assert (abs(net.res_bus_sc.ith_ka.at[1] - 2.348476) < 1e-5)
-    assert (abs(net.res_bus_sc.ith_ka.at[2] - 13.162790807) < 1e-5)
+    assert (abs(net.res_bus_sc.ith_ka.at[2] - 12.470011101) < 1e-5)
 
 
 def test_min_6_trafo(net_transformer):
@@ -97,10 +97,10 @@ def test_min_10_trafo_2ph(net_transformer):
     net = net_transformer
     calc_sc(net, fault="2ph", case='min', ip=True, ith=True, lv_tol_percent=10.)
     assert (abs(net.res_bus_sc.ikss_ka.at[0] - 2.0000000702) < 1e-5)
-    assert (abs(net.res_bus_sc.ikss_ka.at[2] - 11.182525915) < 1e-5)
+    assert (abs(net.res_bus_sc.ikss_ka.at[2] - 10.593970849) < 1e-5)
 
     assert (abs(net.res_bus_sc.ip_ka.at[0] - 4.9384391739) < 1e-5)
-    assert (abs(net.res_bus_sc.ip_ka.at[2] - 28.063977154) < 1e-5)
+    assert (abs(net.res_bus_sc.ip_ka.at[2] - 26.586923262) < 1e-5)
 
 
 #    assert (abs(net.res_bus_sc.ith_ka.at[0] - 2.0000000702) <1e-5)