Top 3 powerflow open source projects

Native, "direct" Python bindings and misc tools for OpenDSS (EPRI Distribution System Simulator). Based on CFFI, DSS C-API and custom patches, aiming for full COM API-level compatibility on Windows, Linux and MacOS.

A Graphical User Interface for the open source pandapower load flow program. [ I was so inexperienced when I started this, but maybe we can try again]

HELMpy, open source package of power flow solvers, including the Holomorphic Embedding Load Flow Method (HELM), developed on Python 3