# DIgSILENT

## Knowledge base

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### How can I simulate a network with unsymmetrical voltages and different phase impedances?

Attached you find an example with 3 unsymmetrical voltage sources. It is required to use 3 symmetrical voltage sources and to connect them to the load busbar using 3 single-conductor cables (phase A…

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### How do I model the harmonic impedance of the network?

For being able to consider frequency dependent network impedances you may use the Voltage Source element (ElmVac) or the External Grid element (ElmXnet). On the Harmonics-page, frequency…

### How can I simulate harmonic voltage distortion resulting from the feeding grid?

There are two ways to simulate the harmonic voltage distortion from the feeding grid: To model the infeed as a voltage source and entering the harmonics on the Harmonics page. To model the infeed as…

### How can I model an asymmetrical AC voltage source (ElmVac) with independent voltage characteristics for each phase?

For load flow calculation, static analysis, the three phase voltages can only be altered by specifying the amplitude and the phase lag in the positive, negative and zero sequence system of the voltage…

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### How can I assign a voltage dip of pre-defined characteristic to a busbar in my system?

Refer to the ]attached example for a measured voltage at a bus bar. The inputs of the voltage source are named U_A, U_B, U_C, as you can see in the composite model. These inputs represent the…

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### Possible implementations of automatic voltage regulators for load flow analysis

The attached example project shows three different possibilities to implement automatic voltage regulators (AVR), installed along a line. The most left arrangement uses an auto transformer, where the…

### How can a harmonic voltage spectrum be converted to a harmonic current injection?

Assuming a harmonic voltage measurement is present and needs to be converted into current injections, the following steps need to be taken:1. Convert the measurement data from phase voltage…

### How can I control a voltage source in a RMS simulation?

The AC voltage source can be controlled in RMS simulation by applying different input values to signal sets (u0,f0) or (U0,F0Hz). The first set controls the per unit quantities, the second absolute…

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### How can I change the voltage set point of an External Source to simulate a voltage drop?

It is not possible to change the voltage set point of an external grid during a simulation. The work around is to replace the external grid by an AC voltage source (ElmVac) and then use one of the…

### How do you model the line energisation of a BI-phase system using a distributed parameter line model?

In the attached PowerFactory project, part of a railway transmission network is modelled based on BI-phase technology. The simple network model contains three 110 kV overhead line sections which are…

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