A Transformer Inrush Mitigation Method

lzmyl

Abstract—Voltage sags are major power quality problems en-
counteredbyindustries.Especiallyforhigh-techcompaniesinside
industry parks, any voltage sag event in the distribution system
could affect many manufacturers and inflict significant losses.
The voltage sag compensator, based on a transformer-coupled
series-connected voltage source inverter, is among the most cost-
effectivesolutiontoprotectsensitiveloads.Oneimportantissueof
thissystemisthetransformerinrushatthestartofsagcompensa-
tion.Theinrushcurrentmaytriggertheover-currentprotectionof
the compensator inverter, and the compensation voltage is greatly
reduced due the magnetic saturation of the coupling transformer.
Oversizing the transformer is a common approach to avoid the
inrushcurrent.However,thiswoulddramaticallyincreasethesize
andweightofthesagcompensationsystem.Thispaperproposesa
newtechniqueformitigatingtheinrushofthecouplingtransformer
and preserving the output voltage for effective sag compensation.
Detailedexplanationsoftheproposedinrushmitigationtechnique
arepresented,andtheeffectivenessoftheproposedschemeisver-
ifiedbylaboratorytestresults.Theinverter-assistedcommutation
sequenceof thebypassthyristors forfast startofthe compensator
is also presented and verified by test results.

hypo_qu

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[ 本帖最后由 hypo_qu 于 2008-11-20 15:02 编辑 ]