Pandapower

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- [CHANGED] units from kW/kVAr/kVA to MW/MVAr/MVA in all elements 73
- [CHANGED] signing system from load to generation in gen, sgen and ext_grid 208
- [CHANGED] all trafo tap parameters from 'tp' to 'tap', tp_mid to tap_neutral 246
- [CHANGED] all trafo short-circuit voltage parameter names from "vsc" to "vk" 246
- [CHANGED] definition of cost functions 211
- [CHANGED] definition of measurements in measurement table 343
- [ADDED] interface to PowerModels.jl for OPF 207
- [CHANGED] removed Python 2 support 224
- [ADDED] load flow and OPF for user-defined temperature of lines, with the optional columns in line table "alpha" and "temperature_degree_celsius" 283
- [ADDED] z_ohm parameter in net.switch to assign resistance to switches 259
- [FIXED] initializing from results also considers auxiliary buses 236
- [ADDED] trafo3w switches are supported in create_nxgraph 271
- [CHANGED] create_nxgraph adds edges in multigraph with key=(element, idx) instead of key=0,1.. 85
- [CHANGED] patch size in create_bus_collection is not duplicated for rectangles anymore 181

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- [CHANGED] Patch size in create_bus_collection is not duplicated for rectangles anymore 181
- [CHANGED] Mask colormap z array to ensure nan handling
- [FIXED] active power distribution in DC OPF for multiple generators at one bus
- [ADDED] support for networkx graphs in json IO
- [ADDED] support for shapely objects in json IO
- [ADDED] switches for three winding transformers 30
- [ADDED] net.bus_geodata.coords to store line representation of busbars and create_busbar_collection to plot them
- [CHANGED] draw_collections also supports tuples of collections
- [ADDED] OPF logging output for verbose=True
- [ADDED] compatibility for pandas 0.24
- [FIXED] bug for single bus networks in DC PF 288

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- [CHANGED] Cost definition changed for optimal powerflow, see OPF documentation (http://pandapower.readthedocs.io/en/v1.6.0/powerflow/opf.html) and opf_changes-may18.ipynb
- [ADDED] OPF data (controllable, max_loading, costs, min_p_kw, ...) in Power System Test Cases
- [ADDED] case_ieee30, case5, case_illinois200
- [FIXED] 1 additional Trafo in case39, vn_kv change in case118, sgen indices in polynomial_cost in case 1888rte, case2848rte
- [ADDED] toolbox functions replace_impedance_by_line(), replace_line_by_impedance() and get_element_indices() including tests
- [CHANGED] new implementation of to_json, from_json for loading and saving grids using functools.singledispatch
- [FIXED] checking similar to "if x: ..." or "x = x or ..." when it is meant "if x is None: ...", because it is potentially problematic with some types
- [FIXED] convert_format: some older pandapower grids had "0" as "tp_side" in net.trafo, this is checked now as well
- [FIXED] create_buses: accepts a single tuple (set the same geodata for all buses) or an array of the corresponding shape (for individual geodata)
- [CHANGED] create_ext_grid_collection (plotting): ext_grid and ext_grid buses can be specified if a collection should only include some of ext grids
- [ADDED] ability to define phase shifting transformers with tp_st_percent 117
- [ADDED] support for multiple voltage controlling elements (ext_grid, gen, dcline) at one bus 134
- [CHANGED] reduced number of arguments in runpp by moving some less important arguments to kwargs 122
- [ADDED] parameters init_vm_pu and init_va_degree to allow independent initialization of bus magnitude and angle 113
- [ADDED] number of power flow iterations are now saved
- [ADDED] calculation of r, x and z for networkx branches
- [ADDED] support for plotly 3.2
- [FIXED] plotly bugfixes for trafo traces and result representation
- [ADDED] Iwamoto algorithm for solving ill-conditioned power flow problems

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- [FIXED] delta-wye transformation for 3W-transformers 54
- [ADDED] bus-bus switches collection 76
- [FIXED] some broken documentation links

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- [FIXED] plotly hover function for edges (only if use_line_geodata == False)
- [FIXED] from_ppc trafo parameter calculation now also considers baseMVA != 100
- [CHANGED] update create_collection docstrings
- [CHANGED] update HV/MV transformer standard type data
- [ADDED] pp_elements() toolbox function
- [ADDED] new parameter g_us_per_km to model dielectric losses in lines
- [ADDED] single phase short-circuit calculation with negative sequence models
- [ADDED] generic storage model (sgen/load like element with negative / positive power allowed)
- [ADDED] modelling of the complex (voltage magnitude and angle) tap changer for cross control
- [ADDED] modelling of the tap changer of a 3-winding transformer at star point or terminals
- [ADDED] losses of 3W transformers can be modeled at star point, HV, MV or LV side

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- [CHANGED] change of collection function names
- [ADDED] sgen collections and ration functionality for sgen and load collections
- [ADDED] cosphi_from_pq toolbox function
- [ADDED] create_nxgraph: respect_switches includes transformer switches