Add unitless solver tolerance option

CHANGELOG.rst

@@ -7,6 +7,7 @@ Change Log
 - [CHANGED] removed deprecated trafo support characteristics table (replaced by trafo_characteristc_table)
 - [ADDED] create function for trafo characteristic entries
 - [ADDED] converter for trafo characteristics
+- [ADDED] Added ``solver_tolerance`` as a unitless power-flow solver tolerance option while keeping ``tolerance_mva`` as a backward-compatible alias.
 
 [upcoming release] - 2026-..-..
 -------------------------------

pandapower/auxiliary.py

@@ -1729,6 +1729,8 @@ def _init_runpp_options(
                             if key not in passed_parameters.keys()}
 
     kwargs.update(overrule_options)
+    solver_tolerance = kwargs.pop("solver_tolerance", None)
+
 
     trafo3w_losses = kwargs.get("trafo3w_losses", "hv")
     v_debug = kwargs.get("v_debug", False)
@@ -1859,6 +1861,8 @@ def _init_runpp_options(
                      consider_line_temperature=consider_line_temperature,
                      distributed_slack=distributed_slack,
                      tdpf=tdpf, tdpf_update_r_theta=tdpf_update_r_theta, tdpf_delay_s=tdpf_delay_s)
+    if solver_tolerance is not None:
+        tolerance_mva = solver_tolerance
     _add_pf_options(net, tolerance_mva=tolerance_mva, trafo_loading=trafo_loading,
                     numba=numba, ac=ac, algorithm=algorithm, max_iteration=max_iteration,
                     v_debug=v_debug, only_v_results=only_v_results, use_umfpack=use_umfpack,

pandapower/run.py

@@ -35,14 +35,14 @@ def set_user_pf_options(net, overwrite=False, **kwargs):
 
     :param net: pandaPower network
     :param overwrite: specifies whether the user_pf_options is removed before setting new options
-    :param kwargs: load flow options, e.g. tolerance_mva = 1e-3
+    :param kwargs: load flow options, e.g. solver_tolerance = 1e-3
     :return: None
     """
     standard_parameters = ['calculate_voltage_angles', 'trafo_model', 'check_connectivity', 'mode',
                            'copy_constraints_to_ppc', 'switch_rx_ratio', 'enforce_p_lims', 'enforce_q_lims',
                            'recycle', 'voltage_depend_loads', 'consider_line_temperature', 'delta',
                            'trafo3w_losses', 'init', 'init_vm_pu', 'init_va_degree', 'init_results',
-                           'tolerance_mva', 'trafo_loading', 'numba', 'ac', 'algorithm',
+                           'tolerance_mva', "solver_tolerance", 'trafo_loading', 'numba', 'ac', 'algorithm',
                            'max_iteration', 'v_debug', 'run_control', 'distributed_slack', 'lightsim2grid',
                            'tdpf', 'tdpf_delay_s', 'tdpf_update_r_theta']
 
@@ -67,7 +67,7 @@ def runpp(net, algorithm='nr', calculate_voltage_angles=True, init="auto",
           max_iteration="auto", tolerance_mva=1e-8, trafo_model="t",
           trafo_loading="current", enforce_p_lims=False, enforce_q_lims=False, check_connectivity=True,
           voltage_depend_loads=True, consider_line_temperature=False,
-          run_control=False, distributed_slack=False, tdpf=False, tdpf_delay_s=None, **kwargs):
+          run_control=False, distributed_slack=False, tdpf=False, tdpf_delay_s=None, solver_tolerance=None, **kwargs):
     """
     Runs a power flow
 
@@ -121,7 +121,8 @@ def runpp(net, algorithm='nr', calculate_voltage_angles=True, init="auto",
             - 30 for "nr" with "tdpf"
             - 40 for "helm"
 
-        tolerance_mva (float, 1e-8): loadflow termination condition referring to P / Q mismatch of node power in MVA
+        solver_tolerance (float, 1e-8): unitless internal solver termination tolerance for the power-flow mismatch equations.
+        tolerance_mva (float, 1e-8): deprecated alias for solver_tolerance. The name is kept for backward compatibility, but the value is treated as a unitless solver tolerance, not as an MVA quantity.
         trafo_model (str, "t"): transformer equivalent circuit model
             pandapower provides two equivalent circuit models for the transformer:
 
@@ -226,6 +227,8 @@ def runpp(net, algorithm='nr', calculate_voltage_angles=True, init="auto",
         parameters["run_control"] = False
         run_control(**parameters)
     else:
+        if solver_tolerance is not None:
+            tolerance_mva = solver_tolerance
         passed_parameters = _passed_runpp_parameters(locals())
         _init_runpp_options(net, algorithm=algorithm,
                             calculate_voltage_angles=calculate_voltage_angles,

pandapower/test/loadflow/test_solver_tolerance.py

@@ -0,0 +1,40 @@
+from pandapower.create import create_bus, create_empty_network, create_ext_grid
+from pandapower.run import runpp, set_user_pf_options
+from math import isclose
+
+from pandapower.test.toolbox.test_grid_modification import net
+
+
+def _minimal_net():
+    net = create_empty_network()
+    bus = create_bus(net, vn_kv=20.0)
+    create_ext_grid(net, bus=bus)
+    return net
+
+
+def test_runpp_accepts_solver_tolerance_alias():
+    net = _minimal_net()
+
+    runpp(net, solver_tolerance=1e-7, numba=False)
+
+    assert net.converged
+    assert isclose(net._options["tolerance_mva"], 1e-7)
+
+
+def test_solver_tolerance_user_pf_option():
+    net = _minimal_net()
+    set_user_pf_options(net, solver_tolerance=1e-6)
+
+    runpp(net, numba=False)
+
+    assert net.converged
+    assert isclose(net._options["tolerance_mva"], 1e-6)
+
+
+def test_tolerance_mva_remains_backward_compatible():
+    net = _minimal_net()
+
+    runpp(net, tolerance_mva=1e-5, numba=False)
+
+    assert net.converged
+    assert isclose(net._options["tolerance_mva"], 1e-5)