Powerflow Playground

Bus inside 0.94 to 1.06 pu
Outside by less than 0.02 pu
Voltage violation
Generator holds its voltage setpoint
Generator
Generator at a reactive limit
Transformer
Line colour shows loading against an illustrative rating: green below 70%, amber 70 to 100%, red above 100%. A busier line is wider. The arrow shows the direction of real power flow.

Bus Generation or load added at this bus System load Enforce generator reactive limits If a generator cannot hold its voltage setpoint inside its Qmin to Qmax range, the solver fixes its Q at the limit. Its voltage then floats.

Generator reactive power

The shaded band is the capability of each machine, from Qmin to Qmax. The tick is the output that the solution needs.

Convergence

The largest power mismatch after each Newton step, on a log scale. Each step roughly squares the error, until it falls below the 10⁻⁸ pu tolerance.

Iteration log

Bus results

What 40% more load does when generators run out of reactive power

I scaled every load in the IEEE 14-bus case to 140% and solved it two times. In the first solve, the generators make all the reactive power they need to hold their voltage setpoints. In the second solve, each generator stays inside its real Qmin to Qmax range. pandapower, an independent open source solver, solved the same case file as a check.

One-line diagram

What 40% more load does when generators run out of reactive power