Note: This appendix is written for users who are using the “Start from a linear network solution” prefault voltage option. You need not read this appendix if you are modeling loads and have been using the “Start from a power flow solution” prefault voltage option.
In North, Central and South America – and in many parts of the world – protection engineers routinely simulate short circuit without modeling the loads.
Without loads in the power system model, it is reasonable to set the real and reactive power output of all generating sources – including synchronous machines, VCCS, CIR and type-3 wind plants – to zero in prefault. Otherwise, it is unpredictable where the power will go.
Some users are under the impression that they have to model the prefault MW generation of wind and solar plants when simulating short circuits. Experience has shown that short-circuit calculations for networks with no loads, the injection of real power from wind and solar plants in prefault distorts the solution, and causes difficulty in convergence.
We created this appendix to show you, in the absence of loads, how to model voltage-controlled current source, current-limited generators, type-3 wind plants, and converter-interfaced resources.
Note: If you plan to compare OneLiner’s short-circuit results against that of a time-domain simulation program, you must set the initial condition of VCCS, CIR and type-3 wind plants in your OneLiner model to match the real and reactive power ouput of the corresponding sources in the time-domain model.