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Number of sidebands setting in Power Analysis module

Edward Sciberras

Posted on 21.08.2017 08:19

In the harmonics calculation tab, there is an option to set the number of sidebands to be considered in the grouping of the harmonics. By default the setting "automatic" is selected. What is the value of this setting? i.e. is this setting automatically set all the groupings according to IEC 61000-4-7 as I could not find any information about that on any of the documentation.

Adjusting this value is giving some very different results on a system with an Active Front End since the switching frequency is a non-integer multiple of the fundamental. How is the grouping sizing best handled in Dewesoft?

DEWESoft Support
Technical support
Posted on 25.08.2017 05:19

Hi,

all settings for the power manual are described in the power manual. The explanation of harmonics and how to set up them is described at page 86 ff.

The harmonic sidebands option is described on page 87. You will find also examples for sideband settings.

The calculation of harmonics is described in standard IEC 61000-4-7. If you leave the option for sidebands at “automatic” one sideband will be considered for harmonic calculation.

That means that in a 50 Hz grid the first harmonic will cover everything from 45 to 55 Hz, the second from 95 to 105 and so on. All parts in between (e.g. from 55 Hz to 95 Hz) you will find in the interharmonic calculation.

However, some standards require using more than 1 sideband. For this purpose, you can define the number of sidebands on your own. Selecting two sidebands will result in a first harmonic from 40 to 60 Hz.

Note: This sideband calculation is based on the number of cycles for the power calculation of 10 for 50 Hz applications and 12 at 60 Hz applications.

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