Short Circuit Analysis Guide

InterPSS short circuit implementation includes 3-Phase(3P), Line to Ground(LG), Line to Line()LL and Line-Line-Ground()LLG faults. The fault can be defined at a bus or on a branch. A distance (percent relative to the From Bus of a branch) is used to define the exact location of a branch fault. Unit bus voltage with a multiplying factor or actual bus voltage, calculated by running Loadflow analysis, could be used as the initial voltage for the short circuit calculation.

Create Short Circuit Project

If you are new to the InterPSS graphic One-line editor, please read the InterPSS Graphic Editor User Guide to get familar with the basic steps to create an InterPSS project.

Project Data

To create a short circuit project, select the Transmission application type and the ACSC network type. You can include loadflow information into your SC case by select the Include Loadflow Information check box.

    • BaseKVA : Base Kva for system PU value
    • BaseFreq : System frequency base.

Bus Data

    • Contribute Bus Type
        • R(1)/R(2)/R(0)(pu):Internal bus resistance (1/2/0 sequence)
        • X(1)/X(2)/X(0)(pu):Internal bus reactance (1/2/0 sequence)
        • SolidGrounded:Solid grounded bus
        • Z-Grounded:Grounded through an impedance Z (GroundR + jGroundX)
        • UnGrounded:Not grounded
    • NonContribute Bus Type - Not input data needed.

If Loadflow information are included in the project, the Loadflow tap would be enabled to allow you to enter loadflow data for the bus. Scripting - Allow you to write custom Java code to define a custom Bus for short circuit analysis, see How to Script InterPSS Bus/Branch Object for details.

Branch Data

Line Branch

    • R1/R0(pu):Line resistance (1/0 sequence). InterPSS assume R(2) = R(1) for line branch.
    • X1/X0(pu):Line reactance (1/0 sequence). InterPSS assume X(2) = X(1) for line branch.
    • 1/2B1/B0(pu):Half Line admittance (1/0 sequence). InterPSS assumes B(2) = B(1) for line branch.

Transformer Branch

In additional to R and X, the following extra date needs to be defined for a transformer branch:

    • From/To TurnRatio(pu):From-side and to-side transformer turn ratio.
    • FromSide/ToSide Grounding:Allow you to define From-Side and To-Side transformer winding connection.
        • Delta Connection:△-connection
        • Wye Connection:Y-connection. For Y-connection, grounding type and optional grounding Z need to be defined.

Phase-Shifting Transformer Branch

Phase-shift transformer needs the same input data as transformer. In addition, a phase-shifting angle (at From-side) needs to be defined. For positive sequence From-side voltage angle will be shifted by the angle value. For negative sequence, the voltage will be shifted by the angle value. For zero sequence, there is no angle shifting.

The Scripting branch type - Allow you to custom Java code to define a custom Branch for short circuit analysis, see How to Script InterPSS Bus/Branch Object for details.

Run Short Circuit Calculation

After completing data entry of a short circuit project, you can click the SC Analysis menu item to run short circuit analysis.

For bus fault, select a bus and Bus Fault type

    • 3P:Three phase to ground fault
    • L-G:Single phase to ground fault
    • L-L:Line to line fault
    • LL-G:Line to line to ground fault
    • L-G(r+jx):Line to ground fault impedance, applicable to 3P, L-G and LL-G
    • L-L(r+jx):Fault impedance between lines, applicable to L-L
    • Loadflow Prefault Voltage:Use loadflow voltage as prefault voltage
    • Fixed Prefault Voltage:Fixed prefault voltage (1.0 pu). You can use the MFactor(%) to increase/decrease fault current contribution
    • MFactor(%): A multiplying factor can be defined increase/decrease fault current contribution

Please note: You only need to define positive sequence data for 3P fault calculation. For L-G, L-L, or LL-G, you need to enter negative and zero sequence data.

For branch fault, select a branch and Branch Fault type. In addition to data defined in the bus fault section,

    • Fault Distance :Define fault location distance in % from the From-Bus.

Short Circuit Output

After a successful SC analysis run, analysis results will be displayed.

In case of non-symmetric faults, current in 012 and ABC coordinates will be displayed.

SC Result Annotation

Short circuit analysis results will be annotated on to the One-line diagram after a short circuit analysis run.

Short Circuit Analysis Report

(ToDo ....)