Merge pull request #2346 from SteffenMeinecke/feature/changelog

add changelog entry

CHANGELOG.rst

@@ -38,6 +38,7 @@ Change Log
 - [FIXED] error during unbalanced powerflow due to out of service external grids
 - [FIXED] PowerFactory converter: fix trafo3w tap dependent impedance
 - [ADDED] PowerFactory converter: support load types (constI, constZ) and the setting whether to consider voltage dependency of loads
+- [CHANGED] vectorization of y_bus reordering in _calculate_equivalent_Ybus() within get_equivalent()
 - [FIXED] deprecation of matplotlib.cm.get_cmap(name) -> matplotlib.colormaps[name]
 - [FIXED] merge_nets failing if net2 has custom DataFrame that is not present in net1
 - [FIXED] fixed some small bugs in the CGMES converter and improved its speed