ESMOGrid validation: Harmonics load flow case 1

Harmonic distortion is “pollution” in the electric power systems. When talking about harmonics, it is usual to distinguish current and voltage harmonics, however, both of those exist together.

All power electronic devices such as variable frequency drives, power inverters and other non – linear loads inject harmonic currents into the grid.

Harmonics cause undesirable and dangerous effects, like overheating of power system equipment and premature ageing.

Therefore, it is important to estimate harmonic distortion level before installing any non-linear equipment. Although, this is a very time consuming task to performer these calculations by hand, as one have to calculate power flow for each of the harmonic current, power system analysis tool ESMOgrid has a feature to execute these calculations within a blink of an eye.

The harmonics load flow studies from ESMOgrid and scientific paper “Adjustable Speed Drive and Power Rectifier Harmonics – Their Effect on Power Systems Components” are compared. Scientific paper was published in IEEE Transactions on industry applications, VOL. IA-22, NO. 1, January 1986 by David E. Rice.

Calculated power system is depicted in Fig.1. Harmonic current source is inverter connected to 5th bus. Its harmonic currents in percents of inverter base amperes are presented in Table 1.

Fig. 1 One line scheme of analyzed distribution system with harmonics source

Fig. 1 One line scheme of analyzed distribution system with harmonics source

Table 1 Harmonic currents of power converter
Harmonic Currents, %
5 15.83
7 8.95
11 2.83
13 1.77
17 1.24
19 1.04
23 0.62
25 0.51

Results are depicted in the following pictures exported from ESMOGrid.

Fig. 2 Harmonics load flow results from bus 1 to bus 2

Fig. 2 Harmonics load flow results from bus 1 to bus 2

Fig. 3 Harmonics load flow results from bus 2 to bus 3

Fig. 3 Harmonics load flow results from bus 2 to bus 3

Fig. 2 Harmonics load flow results from bus 5 to bus 4

Fig. 4 Harmonics load flow results from bus 5 to bus 4

Calculation error is 0.00% in all cases.

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