This the PowerFactory model for calculation of Max short circuit current.It shows the fault levels at each bus.It is very clear that the figures of the model are very identical to hand calculations.For example, the fault current at load bus is 202.7 A as shown in the PowerFactory model and hand calculations.

This the PowerFactory model for calculation of minimum short circuit current.It shows the fault levels at each bus.It is very clear that the figures of the model are very identical to hand calculations.For example the fult current at load bus = 165 A in the model and the theoritical calculations.

You will notice that the second transformer is isolated.This is very important when calculating the min short circuit level.Changing the type of fault does not guarantee that we are calculating the min possible fault current, operational scenario will also affect the calculations.

Modelling of Power Systems Using DIgSILENT PowerFactory

This is a simple example to show the accuracy and validity of the most powerfull powers

system analysis software.

Example shows Exel hand calculations.

The figure below shows the DIgSILENT PF software model.

It is very clear that both calculations are matching.

Thanks for posting this interesting topic.

I have also similar example

which can be used to compare the hand results

with that of PowerFactory.

This is the SLD of the power network

Here is the hand calculation

This the software model showing 3 phase maximum fault current

This is the software model showing 2 phase minimum fault current result.

It is very clear that the PowerFactory results

are very highly valid and similar to hand calculations.

Example of Over Current Protection Setting using DIgSILENT PowerFactory

This exercise shows how the PF can be used to calculate fault currents and set an overcurrent relay. The coordination graphs will be shown and tripping calculations will be displayed.

Modelling of the network using PowerFactory

The first setp is to model the network. This is done by creating a new project.

Calculation of Maximum and Minimum Fault Currents

As known from basic power system theory that the maximum fault current occurs at network when we have three phase fault.

The figure below shows the result when parameters are defined in the PwerFactory model.

The maximum fault current = 875 A as expected.

The minimum fault current = 758 A as expected

The next step is to define the protection relay.

Right click below the transformer and select New Devices -----> Relay Model

At Relay Type click Select Global Type

This will take you to library as shown in figure below.Choose the following relay as an example in this exercise. Other relays can be used if desirable.

Library ----> Relays ----> Relays ----> select then Overcurrent Relays ----> GE Alstom ----> MCGG Series ----> MCGG-22.

Now it is time to define the CT for this relayClick on Create CT as shown below

Then choose currnet ratio ----> write 800 A in primary. Click OK

Now we need to display the rely using colour.Click on colour map as shown below.

Then from drop down menu select Relays, Current and Voltage Transformers as shown

When you click OK, the SLD shows now the line in Red where relay is connected.

We need now to create the graph for the protection devices.

Right click on the SLD where the relay is connected as sown below.Then select Create Time-Overcurrent Plot.

The log graph appears as another sheet as shown below.

We can also click right on the graph and add the Transformer Damage Curve as shown.

Colour of Transformer Damage Curve can be chosen as shown below.

We can also select the voltage base for displaying the graphs, as shown below.

There is also of course option to display the fault current (875 A) in different colour (blue)and also the tripping time of relay (1.357 s) for that fault current.