Isimiso Sokusebenza Sejeneretha Evumelanisiwe
Amajeneretha ahambisanayo angomunye wemishini kagesi esetshenziswa kakhulu ezinhlelweni zamandla zesimanje, ikakhulukazi ezitshalweni zamandla ezinkulu njengezitshalo zamandla ezisebenzisa amalahle (PLTU), izitshalo zamandla kagesi (PLTA), izitshalo zamandla ezisebenzisa igesi (PLTG), kanye nezitshalo zamandla enuzi (NPT). Abizwa ngokuthi "ahambisanayo" ngoba isivinini sawo sokujikeleza kwe-rotor sihlala sihlobene ngqo (ahambisanayo) nemvamisa ye-voltage kagesi ekhiqizwayo. Ngamanye amazwi, amajeneretha ahambisanayo aguqula amandla omshini avela ku-prime mover (i-turbine yamanzi, i-turbine yesitimu, i-turbine yegesi, noma injini yedizili) abe amandla kagesi ashintshanayo (AC) ngemvamisa eqinile. Ukuze siqonde ukuthi asebenza kanjani, sidinga ukuhlola isakhiwo sawo, umqondo wamasimu kazibuthe, ukungeniswa kwe-electromagnetic, ubudlelwano be-speed-frequency, kanye nezinqubo zokulawula ukuvusa kanye ne-voltage.
1. Incazelo kanye nomsebenzi wamajeneretha ahambisanayo
Ijeneretha ehambisanayo (evame ukubizwa ngokuthi i-alternator) ikhiqiza i-voltage ye-AC yesigaba ezintathu ohlelweni lwamandla. Esiteshini samandla, le jeneretha "iyinhliziyo" yesistimu, iguqula i-torque kusuka ku-prime mover shaft ibe amandla kagesi, bese inyuswa yi-transformer ngaphambi kokuba isatshalaliswe kunethiwekhi yokudlulisa. Inzuzo yayo eyinhloko ikhono layo lokukhiqiza i-voltage ngemvamisa engaguquki inqobo nje uma ukujikeleza kwe-shaft kugcinwa ngenani layo elihambisanayo.
Ngokuyisisekelo, ijenereyitha ehambisanayo isebenza ngokusekelwe emthethweni kaFaraday wokungeniswa kwe-electromagnetic: ushintsho ekugelezeni kwe-magnetic kumqhubi kagesi lukhiqiza amandla e-electromotive (EMF) noma i-voltage ebangelwayo. Kujenereyitha, lolu shintsho lokugeleza lwenzeka ngoba insimu yamagnetic ejikelezayo (ku-rotor) inqamula ama-stator coils.
2. Ukwakhiwa okuyinhloko: i-stator ne-rotor
Amajeneretha ahambisanayo aqukethe izingxenye ezimbili eziyinhloko:
1. I-Stator (ingxenye engashintshi)
I-stator iqukethe umongo wensimbi onama-laminated kanye nama-coil ezigaba ezintathu (ngokuvamile axhunywe kuxhumano lwenkanyezi/i-wye). Yilapho kukhiqizwa khona i-AC voltage ebangelwayo. Ngenxa yokuthi i-stator ayijikelezi, ukusatshalaliswa kwamandla ohlelweni kulula futhi kuphephile, ikakhulukazi kuma-voltage aphezulu.
2. I-Rotor (ingxenye ejikelezayo)
I-rotor ithwala insimu yamagnetic. Le nsimu ivame ukukhiqizwa yi-direct current (DC) egeleza ngama-rotor field coils. Lapho i-rotor ijikeleziswa yi-prime mover, insimu yamagnetic ye-rotor iyajikeleza futhi "ishanele" ama-stator coils, okubangela i-AC voltage.
Ngokuvamile kunezinhlobo ezimbili zama-rotor ejeneretha ahambisanayo:
– I-rotor yezinsika eziqinile: izinsika eziningi, ezifanelekela isivinini esiphansi njengezitshalo zamandla kagesi.
– I-rotor eyi-cylindrical (i-rotor engeyona ephawulekayo / i-turbo): izigxobo ezingeyona ephawulekayo, ezifanele ukuzungeza okuphezulu njenge-PLTU/PLTG.
3. Izimiso eziyisisekelo zokungeniswa kwe-AC voltage
Cabanga nge-rotor njengomagnethi omkhulu, ojikelezayo. Njengoba izigxobo ze-rotor ezisenyakatho-ningizimu zidlula ikhoyili ye-stator, i-flux ehambisana nekhoyili iyashintsha njalo: isezingeni eliphezulu lapho izigxobo zibheke ngqo ikhoyili futhi isezingeni eliphansi uma zikude. Lokhu kushintsha kwe-flux kudala i-emf ebangelwayo eshintsha njalo njalo—umphumela uba yi-voltage eshintshanayo.
Kujeneretha yezigaba ezintathu, ama-stator coil ahlelwe ngamadigri kagesi ayi-120 ahlukene. Lokhu kuphumela kuma-voltage amathathu e-sinusoidal angamadigri ayi-120 angaphandle kwesigaba. Lokhu kulungiselelwa kwezigaba ezintathu kukhethwe ngoba kusebenza kahle ekudluliseni amandla, kukhiqiza i-torque ebushelelezi emithwalweni yemoto, futhi kuvumela amandla aphezulu.
4. Ubudlelwano phakathi kwesivinini esivumelanayo, imvamisa, kanye nenani lezinsika
Isici esibaluleke kakhulu "esihambisanayo" ubudlelwano bezibalo phakathi:
– imvamisa kagesi (f) ku-Hz,
– inani lezinsika (P) zerotor,
– isivinini sokuzungeza i-rotor (Ns) ngo-rpm.
Ifomula:
\[
N_s = \frac{120 \, f}{P}
\]
Kusho ujuthi:
– Uma uhlelo luyi-50 Hz futhi ijeneretha inamapali amabili, khona-ke:
\[
N_s = \frac{120 \izikhathi 50}{2} = 3000 \umbhalo{rpm}
\]
– Uma izinti ezine:
\[
N_s = \frac{120 \izikhathi 50}{4} = 1500 \umbhalo{rpm}
\]
Uma izigxobo eziningi, isivinini esihambisanayo siyancipha ukuze kukhiqizwe imvamisa efanayo. Yingakho izitshalo zamandla kagesi (ama-turbine ajikelezayo kancane) zivame ukusebenzisa ama-rotor aqinile anezigxobo eziningi, kuyilapho izitshalo zomusi/igesi (ama-turbine asheshayo) zivame ukusebenzisa ama-turbo rotors anezigxobo ezimbalwa.
Kujeneretha ehambisanayo, i-rotor ijikeleza ngesivinini esihambisanayo uma ixhunywe ohlelweni lwamandla oluzinzile. Izinguquko zomthwalo zithinta i-engeli yamandla kanye nogesi ngaphezu kwemvamisa, inqobo nje uma igridi iqinile futhi i-prime mover ilawulwa kahle.
5. Uhlelo lokuvusa: umthombo wensimu yamagnetic ye-rotor
Ukuze ijeneretha ikhiqize i-voltage, i-rotor kumele ibe nensimu yamagnetic. Le nsimu ikhiqizwa ngokuvusa—ukusetshenziswa kwamandla kagesi e-DC kukhoyili yensimu ye-rotor. Kunezindlela eziningana zokuvusa:
- Ukuzijabulisa ngamasongo okushelela namabhulashi
Ugesi we-DC unikezwa ngamasongo okushelela kuma-rotor coil. Le ndlela ilula kodwa idinga ukulungiswa kwebhulashi.
- Ukuvuselela okungenamabhulashi
Kusetshenziswa i-exciter (ijeneretha encane) kanye ne-rectifier ejikelezayo, i-DC current ye-rotor ikhiqizwa ku-shaft efanayo ngaphandle kwamabhulashi. Lokhu kuvamile kumajeneretha anamuhla ngoba athembeke kakhulu.
Ubukhulu bomsinga wokuvuselela buthinta ubukhulu bensimu yamagnetic, okugcina kuthinta i-voltage yesiphetho sejeneretha kanye namandla asabelayo ashintshaniswa nohlelo.
6. Ukukhiqizwa kwe-voltage kanye nokulawulwa kwayo (i-AVR)
I-voltage ebangelwa yi-stator incike ezintweni eziningana, ikakhulukazi:
– amandla e-rotor magnetic field (athonywe yi-excitation current),
– isivinini sokujikeleza (esihlobene nemvamisa),
– inani lokujika kanye nomklamo wekhoyili ye-stator.
Empeleni, i-voltage yesiphetho sejeneretha kumele igcinwe ngaphakathi kwemingcele ejwayelekile ngisho noma umthwalo ushintsha. Ngakho-ke, kusetshenziswa i-Automatic Voltage Regulator (AVR). I-AVR iqapha i-voltage yesiphetho bese ikhuphula noma yehlisa ugesi we-rotor ukuze igcine i-voltage izinzile.
Njengoba umthwalo ukhuphuka, ugesi we-stator uyanda, okuholela ekwehleni kwe-voltage ngenxa yokuphazamiseka kwangaphakathi kwejeneretha. I-AVR "izobuyisela" ngokwandisa ukuvusa ukuze kulondolozwe ugesi.
7. Ukusebenza okuhambisanayo nenethiwekhi (ukuvumelanisa)
Ngaphambi kokuba ijeneretha ehambisanayo ixhunywe kugridi yamandla, inqubo yokuvumelanisa kumele yenziwe, okungukuthi ukulinganisa:
1. I-Voltage (inani le-RMS),
2. Imvamisa,
3. Ukulandelana kwesigaba,
4. I-engeli yesigaba ngesikhathi sokuvala i-breaker.
Uma ijeneretha ixhunywe kugridi ngaphandle kokuvumelanisa okufanele, ingadala amaza amakhulu okushaqeka kanye ne-torque engazelelwe yomshini engalimaza imishini. Uma isixhunyiwe, isivinini se-rotor "sivalelwe" ku-frequency yesistimu (sihlala sivumelanisiwe), kuyilapho amandla asebenzayo enqunywa kakhulu yi-torque ehamba phambili.
8. Amandla asebenzayo kanye namandla asebenzayo kumajeneretha ahambisanayo
Kuhlelo lwe-AC, ijeneretha inikeza:
– Amandla asebenzayo (P): ahlobene namandla angempela asetshenziswa umthwalo (kW noma MW).
– Amandla asebenzayo (Q): ahlobene nokwakheka kwensimu yamagnetic kumthwalo we-inductive/capacitive (kVAr noma MVAr).
Ngenjwayelo:
– Amandla asebenzayo alawulwa ngokulungisa i-torque/i-mechanical input (isb. ukuvulwa kwe-steam valve, ukugeleza kwamanzi, noma ukuphakelwa kukaphethiloli).
– Amandla asebenzayo kanye ne-voltage ye-terminal kulawulwa yi-excitation current.
Uma ukuvusa kukhushuliwe (kuvukwe kakhulu), ijenereyitha ivame ukunikeza amandla okusabela kugridi futhi isize ekukhuphuleni i-voltage yesistimu. Uma ukuvusa kuncishisiwe (kuvukwe kancane), ijenereyitha imunca amandla okusabela futhi i-voltage ivame ukwehla.
9. Isiphetho
Isimiso sokusebenza sejenereyitha ehambisanayo sisekelwe ekungenisweni kwe-electromagnetic: i-rotor ejabule kakhulu ye-DC ikhiqiza insimu kazibuthe ejikelezayo, enquma ama-stator coils futhi ibangele i-voltage ye-AC yesigaba esithathu. Ukuhluka kwejenereyitha ehambisanayo ubuhlobo obuqondile phakathi kwemvamisa yokuphuma kanye nesivinini sokujikeleza kanye nenani lezigxobo, ezakhiwe njenge-\(N_s = 120f/P\). Ekusebenzeni kwangempela, ukuzinza kwe-voltage kugcinwa yi-AVR ngokulawulwa kokuvuselela, kuyilapho amandla asebenzayo elawulwa yi-prime mover. Ngenxa yokusebenza kwawo okuzinzile, ukusebenza kahle okuphezulu, kanye nekhono lokulawula i-voltage kanye namandla asebenzayo, amajenereyitha ahambisanayo ayinsika yokukhiqizwa kwamandla kagesi kanye nezinhlelo emhlabeni jikelele.
