### Do you have an example in EMT simulation of harmonic currents injection?

Category:
Dynamic Simulation
Answer

In the attached PowerFactory project, a current source is configured to inject fundamental frequency and harmonic currents into the system. The simple network model contains a current source which is connected to an external grid by a line.

The current source is controlled by a DSL model, which feeds the current source with the instantaneous values of all three phase currents. The DSL model itself gets its data from three Fourier Source elements (ElmFsrc), which convert a configured harmonic spectrum into a time domain output signals of the corresponding phase. The harmonic spectrum is defined by the amplitudes for each harmonic order and angle. For the harmonic spectrum in the example, all three phases will inject the same harmonic currents. For the angles the following applies:

- The harmonics with order h = 3, 6, 9, … (h=3 i) are in the zero sequence. Thus the angle equals 0° for all phases.

- Harmonics with h = 1, 4, 7,… (h =3 i + 1) are in the positive sequence. The angles for the positive sequence are the same as for the fundamental frequency.

- Finally harmonics with h = 2, 5, 8, … (h = 3 i – 1) are in the negative sequence. Consequently the angle sequence of the 120° shift is opposite to the fundamental frequency.

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