One of the problems of electrical networks
of industrial enterprises is a substantial distortion of the quality of electric power, including the presence
of inadmissible voltage oscillations which lead to the fluctuations of lighting and affect the ability to work
and human’s health. The use of special technical devices for reducing the oscillations needs considerable
expenses. Therefore, first of all, one should regard all possible measures (diagrammatic, organizational) that
don’t lead to extra capital investments.
The aim of the work is the analysis of the possibility
of considering workshop transformers as a measure that reduces voltage oscillation with substantiating the means
of providing the quality of electric power.
There are authors (for example, Saltykova O.O., Russia)
who think that workshop transformers influence the reduction of voltage oscillations, but this statement needs
additional examination.
One can examine reducing voltage oscillations by
transformers in two ways:
by the scheme of substituting transformers;
by the scheme of substituting transformers taking into account low-frequency modulation.
In the work two schemes of transformers’ substitution were considered: T-like and the scheme without the contour of magnetic bias. The results of calculations showed that the absence of the contour of magnetic bias leads to a small error that doesn’t surpass 0,1 %, i.e. the examination can be fulfilled on the simplest scheme of substitution.
In the result of calculation it was determined that transformers reduce voltage oscillations in the network. With the inductive load the reduction of oscillations is three times more than with the active one. With the active-inductive load when the load is the same, the voltage oscillations are better reduced by transformers with lower nominal power (i.e. the more loaded transformer) or with higher voltage of short ciruit. With the active load the best in reducing volage oscillations is a transformer of lower nominal power, and with the inductive – the other way round. All-Union State Standard 13109-97 points that with rectangular voltage oscillations their amplitude may be 0,29 % nd higher.
The calculation showed that transformers can reduce voltage oscillations by 1 %, if the transformer ÒÌ-100/10 is loaded by 50 %, ÒÌ-400/10 – by 66,9 % and ÒÌ-630/10 – by 76,5 % with active load only. This is a significant magnitude.
Thus, we can make a conclusion that in designing electric power systems workshop transformers should be considered as a possible measure of restricting voltage oscillations.
© 2008 DonNTU