1. Gauss Seidel Powerflow Solution -> Fast convergence but not too accurate
2. Newton Raphson Powerflow Solution -> Slow convergence but very accurate
3. Fast Decoupled Powerflow Solution -> Good convergence and good accuracy
To know more about these solutions, you can check out this wikipedia page: https://en.wikipedia.org/wiki/Power-flow_study
The code for all three methods was used to solve the following powerflow problem:
http://www.mty.itesm.mx/etie/deptos/ie/profesores/jabaez/clases/e00888/flujos_potencia/ejemplo_flujos_uwaterloo.pdf