Power Flow did not converge

The power flow is an iterative algorithm. It stops when the convergence criterion is met (voltage change from previous iteration < threshold) or when a maximum number of iterations is reached (1000 by default).

A non-convergence typically indicates a data problem.

1. The amount of power in the grid is too high. E.g. power value was entered in MW instead of kW or a Smart Meter measured an outlier.
2. The electrical properties of the grid model are incorrect. E.g. line length was added in km instead of meters, leading to extremely high impedances.

Check power and electrical parameters

The software shows multiple statistics to help you narrow down the problem:

• ∑S / ∑P / ∑Q The sum of the residual apparent/active/reactive power of all buses in the grid. This will help you asses if the overall loaded is unrealistic. E.g. multiple MW in a low voltage grid is unrealistic.
• Smax The power and ID of the bus with the highest residual load are shown. If the non-convergence comes from a single outlier, this usually identifies it.
• Zmax The branch with the highest impedance. This usually helps to identify a branch, where e.g. the length is in km instead of meters or the impedance [Ω/km] is entered incorrectly.
• V̅ The average voltage of all buses in the grid during the last iteration of the power flow algorithm. An average voltage close to 0 indicates too much power consumption, and an average voltage significantly larger than 1 indicates too much power production.

Check power flow options

In some rare cases, the non-convergence is caused by bad power flow algorithm settings. You can try to:

• increase the maximum number of iterations to e.g. 2000 (Default is 1000)
• increase the convergence threshold to e.g. 1e-5 (default is 1e-6)
• change the selected algorithm. For radial grids, Sweeping is best, for meshed grids Full Newton is best (default is Full Newton)