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1、第39卷第11期電力系統(tǒng)保護與控制Vl0l_39NO.112011年6月1日PowerSystemProtectionandControlJun.1.2011基于等效模型的介質損耗數(shù)值算法徐志鈕,律方成(生物質發(fā)電成套設備國家工程實驗室(華北電力大學),河北保定071003)摘要:基于電阻和電容并聯(lián)或串聯(lián)等效電路模型提出了一種在非整周期情況下仍有較高精確度的介損數(shù)字化算法。測量電容型設備絕緣上的電壓和泄漏電流信號后使用傅里葉算法或加窗插值傅里葉算法和修正理想采樣頻率法獲得信號的諧波分量,分別根據阻容并聯(lián)/串聯(lián)
2、等效電路模型以及電壓信號對電流信號進行擬合,并將擬合模型中的變量進行適當?shù)霓D化后使模型由非線性最小二乘變?yōu)榫€性最小二乘,直接計算獲得電阻、電容進而得到介損和擬合泄漏電流信號,從而簡化了計算。對仿真信號和實測信號的處理結果表明:阻容并聯(lián)和阻容串聯(lián)模型均能較好擬合電流信號,前者精度稍高;根據等效模型算法擬合后的電阻、電容計算所得介損在不同信號頻率下仍有較高精確度,且該方法可獲得絕緣的等效電阻和電容。關鍵詞:電氣設備;電介質;介質損耗;等效電路模型;最小二乘;頻率Dielectriclossdigitalalgor
3、ithmbasedonequivalentcircuitmodelxuZhi·niu,LtiFang-cheng(NationalEngineeringLaboratoryforBiomassPowerGenerationEquipment,NorthChinaElectricPowerUniversityBaoding071003,China)Abstract:AdielectriclOSSdigitalalgorithmbasedonparallelorseriesequivalentcircuitmod
4、elofresistanceandcapacitanceiSproposed,andthealgorithmstillhashighaccuracyinnon-integerperiodssampling.Inthepaper,thevoltageandleakagecurrentsignalofcapacitiveelectricalequipmentinsulationaremeasured,andthosesignalharmonicsareobtainedbytheFourieralgorithmor
5、thewindowingandinterpolationFourieralgorithmandmodifiedidealsamplingfrequencymethod.Theleakagecurrentsignalisfittedbytheparallel/seriesequivalentcircuitmodelandthevoltagesigna1.Inthemeantime,varianceofthemode1.iStransformedtomakethemodelrumfromanon.1inearle
6、astsquaremodelintoalinearleastsquaremodel,whichhaslesscalculationwork,thentheresistanceandcapacitanceofthecircuitmodeliScalculateddirectly.Afterthen,thedielectriclOSSandthefitedleakagecurrentsignalofthecapacitiveequipmentareobtained.Theabovealgorithmsareuse
7、dtoprocessthesimulatedandrealmeasuredsignals,andtheresultindicatesthattheleakagecurentsignalcanbefittedwellbyparallelorseriesequivalentcircuitmodel,andtheformerhashigherfitingaccuracy;thedielectriclosscalculatedbytheproposedalgorithmsisaccurateindifferentsi
8、gnalfrequencies,inthemeantimethealgorithmcangiveequivalentresistanceandcapacitance.Keywords:electricalequipment;dielectric;dielectriclOSS;equivalentcircuitmodel;leastsquare;frequency中圖分類號:TM835.4文獻標識碼: