Ma inverter ali m'gulu lalikulu la ma converter osasinthasintha, omwe akuphatikizapo ambiri a masiku ano.'zipangizo zomwe zimatha“sinthani"magawo amagetsi olowera, monga magetsi ndi ma frequency, kuti apange kutulutsa komwe kumagwirizana ndi zofunikira za katundu.

Kawirikawiri, ma inverter ndi zipangizo zomwe zimatha kusintha mphamvu yolunjika kukhala mphamvu yosinthira ndipo ndizofala kwambiri m'mafakitale odzipangira okha komanso ma drive amagetsi. Kapangidwe ndi kapangidwe ka mitundu yosiyanasiyana ya ma inverter kamasintha malinga ndi ntchito iliyonse, ngakhale cholinga chawo chachikulu chili chimodzimodzi (kusintha kwa DC kupita ku AC).

1. Ma Inverter Odziyimira Pawokha komanso Olumikizidwa ndi Grid

Ma inverter omwe amagwiritsidwa ntchito mu ntchito za photovoltaic amagawidwa m'magulu awiri akuluakulu m'mbiri:

:Ma inverter odziyimira pawokha

:Ma inverter olumikizidwa ndi gridi

Ma inverter odziyimira pawokha ndi a ntchito zomwe fakitale ya PV siilumikizidwa ku netiweki yayikulu yogawa mphamvu. Inverter imatha kupereka mphamvu zamagetsi ku katundu wolumikizidwa, kuonetsetsa kuti magawo akuluakulu amagetsi (voltage ndi frequency) ali olimba. Izi zimawasunga mkati mwa malire omwe adakhazikitsidwa kale, kuti athe kupirira zovuta kwakanthawi. Pachifukwa ichi, inverter imalumikizidwa ndi njira yosungira batri kuti iwonetsetse kuti mphamvu ikupezeka nthawi zonse.

Koma ma inverter olumikizidwa ndi gridi amatha kuyanjana ndi gridi yamagetsi yomwe amalumikizidwa nayo chifukwa, pankhaniyi, magetsi ndi ma frequency ndi“kukakamizidwa"ndi gridi yayikulu. Ma inverter awa ayenera kukhala okhoza kulekanitsa ngati gridi yayikulu yalephera kuti apewe kubwereranso kwa gridi yayikulu, komwe kungakhale koopsa kwambiri.

Chithunzi 1 - Chitsanzo cha makina odziyimira pawokha ndi makina olumikizidwa ndi gridi. Chithunzi mwachilolezo cha Biblus.

2. Kodi Ntchito ya Bus Capacitor ndi Chiyani?

Cholinga cha inverter ndikusintha magetsi a DC waveform kukhala chizindikiro cha AC kuti alowetse mphamvu mu katundu (monga gridi yamagetsi) pafupipafupi komanso ndi ngodya yaying'ono ya gawo (φ ≈0). Dera losavuta la single phase unipolar Pulse-Width Modulation (PWM) likuwonetsedwa pachithunzichi.2 (chiwembu chomwecho chikhoza kuwonjezeredwa ku dongosolo la magawo atatu). Mu chithunzichi, dongosolo la PV, lomwe limagwira ntchito ngati gwero la magetsi la DC lomwe lili ndi inductance inayake, limapangidwa kukhala chizindikiro cha AC kudzera mu ma switch anayi a IGBT motsatizana ndi ma freewheeling diode. Ma switch awa amawongoleredwa pachipata kudzera mu chizindikiro cha PWM, chomwe nthawi zambiri chimakhala chotuluka cha IC chomwe chimayerekeza mafunde onyamula (nthawi zambiri mafunde a sine a ma frequency ofunikira) ndi mafunde ofotokozera pama frequency apamwamba kwambiri (nthawi zambiri mafunde a triangle pa 5-20kHz). Kutuluka kwa ma IGBT kumapangidwa kukhala chizindikiro cha AC choyenera kugwiritsidwa ntchito kapena jekeseni wa grid kudzera mukugwiritsa ntchito ma topologies osiyanasiyana a ma LC filters.

Pezani Mtengo

Chithunzi 2: Kusinthasintha kwa Mpweya (PWM) gawo limodzikukhazikitsa inverter. Ma switch a IGBT, pamodzi ndi LC output filter, amapanga DC input signal kukhala AC signal yogwiritsidwa ntchito. Izi zimapangitsaKuphulika kwa magetsi olakwika kudutsa ma terminal a PV. BasiKachipangizo kameneka kamapangidwa kuti kachepetse kugwedezeka kumeneku.

Kugwira ntchito kwa ma IGBT kumabweretsa mphamvu ya ripple pa terminal ya PV array. Ripple iyi ndi yoyipa pakugwira ntchito kwa PV system, popeza nominal voltage yomwe imagwiritsidwa ntchito kuma terminal iyenera kugwiridwa pa max power point (MPP) ya IV curve kuti ichotse mphamvu zambiri. Ripple ya voltage pama PV terminals idzasokoneza mphamvu yochotsedwa mu system, zomwe zimapangitsa kuti

mphamvu yotsika (Chithunzi 3). Capacitor imawonjezedwa mu basi kuti ichepetse kugwedezeka kwa magetsi.

Chithunzi 3: Kuphulika kwa magetsi komwe kumayikidwa pa ma terminal a PV ndi PWM inverter scheme kumasuntha magetsi ogwiritsidwa ntchito kuchokera pa max power point (MPP) ya PV array. Izi zimayambitsa kuphulika kwa mphamvu yotulutsa magetsi ya array kotero kuti mphamvu yotulutsa yapakati imakhala yotsika kuposa MPP yodziwika bwino.

Kutalika kwa mphamvu yamagetsi (kuyambira pa peak mpaka peak) kumatsimikiziridwa ndi ma switching frequency, PV voltage, basi capacitance, ndi fyuluta inductance malinga ndi:

komwe:

VPV ndi mphamvu yamagetsi ya DC ya solar panel,

Cbus ndi mphamvu ya capacitor ya basi,

L ndiye kulowetsedwa kwa ma inductors osakaniza fyuluta,

fPWM ndi ma frequency osinthira.

Equation (1) imagwira ntchito pa capacitor yoyenera yomwe imaletsa mphamvu kuti isayende kudzera mu capacitor panthawi yochaja kenako n’kutulutsa mphamvu yomwe ili m’munda wamagetsi popanda kukana. M’chenicheni, palibe capacitor yoyenera (Chithunzi 4) koma imapangidwa ndi zinthu zingapo. Kuwonjezera pa capacitance yoyenera, dielectric siilimbana bwino ndipo mphamvu yaying’ono yotuluka imayenda kuchokera ku anode kupita ku cathode motsatira finite shunt resistance (Rsh), kudutsa dielectric capacitance (C). Pamene mphamvu yodutsa mu capacitor ikuyenda, mapini, ma foil, ndi dielectric sizikuyenda bwino ndipo pali equivalent series resistance (ESR) motsatizana ndi capacitance. Pomaliza, capacitor imasunga mphamvu zina mu magnetic field, kotero pali equivalent series inductance (ESL) motsatizana ndi capacitance ndi ESR.

Chithunzi 4: Dongosolo lofanana la capacitor wamba. Capacitor ndiYopangidwa ndi zinthu zambiri zosayenerera, kuphatikizapo dielectric capacitance (C), kukana kosatha kwa shunt kudzera mu dielectric komwe kumadutsa capacitor, series resistance (ESR), ndi series inductance (ESL).

Ngakhale mu gawo looneka ngati losavuta ngati capacitor, pali zinthu zambiri zomwe zingalephere kapena kuwonongeka. Chilichonse mwa zinthuzi chingakhudze khalidwe la inverter, mbali zonse za AC ndi DC. Pofuna kudziwa momwe kuwonongeka kwa zigawo za capacitor zomwe sizili bwino zimakhudzira mphamvu yamagetsi yomwe imayikidwa m'malo olumikizirana a PV, inverter ya PWM unipolar H-bridge (Chithunzi 2) idayesedwera pogwiritsa ntchito SPICE. Ma capacitor ndi ma inductor osinthira amasungidwa pa 250µF ndi 20mH, motsatana. Mitundu ya SPICE ya ma IGBT imachokera ku ntchito ya Petrie et al. Chizindikiro cha PWM, chomwe chimawongolera ma switch a IGBT, chimatsimikiziridwa ndi dera loyerekeza ndi inverting comparator la ma switch a IGBT apamwamba ndi otsika, motsatana. Zolowera za ma control a PWM ndi ma wave a 9.5V, 60Hz sine carrier ndi ma wave a triangular a 10V, 10kHz.