Maimaita karamin gaban karami suna da yawan abubuwa ga wasu manyan tsohon karamin gaban karami, ciki har da fossil - fired, nuclear, gas turbine, combined - cycle, hydro, da kuma pumped storage power plants. Su ne kuma mafi inganci wajen gina wasu tsohon karamin gaban karami masu karfin maimaita karamin gaban karami.
A lokacin da ya bace, maimaita karamin gaban karami suna amfani a wasu tsohon karamin gaban karami da ke da shugabannu daga cikin kungiyar jama'a, inda akwai wasu karamin gaban karami na musamman da suka zama sabbin birnin. Amma, saboda hanyoyin yawan karamin gaban karami da kuma ciyar hanyoyin system fault current levels, aikinsu da za a iya haɗa wannan nau'in switchgear ta yi an samu. Saboda haka, ana amfani da raddar tsohon karamin gaban karami, inda karamin gaban karami kamar yawa ce ke da steam supply auxiliary system mai sarrafa da step - up transformer da high - side breaker(s).
Idan a bayyana da raddar tsohon karamin gaban karami, amfani da maimaita karamin gaban karami don kada karamin gaban karami a tsarin voltage masu babban abubuwa:
Amfani Da Aiki: Yana taimakawa wajen kula tsari na aiki, ta haka ya kawo yawan matsaloli a lokacin da ake kada karamin gaban karami.
Aiki Mai Inganci: Yana ba da inganci masu daidai don karamin gaban karami, kamar kafin main da unit transformers, don hana waƙo su daga faults da surges.
Zama Zafi: Yana zama zafi na tsohon karamin gaban karami, kuma yana kara ilimi na tsohon karamin gaban karami, tare da kuma kudaden ilimi.
Farkon Arziki: Yana ba da farkon arziki, kamar kudaden kosai da kuma ingancin aiki a lokacin da takaice.
Tsarin aiki na tsohon karamin gaban karami suna da muhimmanci kamar yadda ake nufin:
Kada Ilimi Daga Karamin Gaban Karami: Kada ilimi na karamin gaban karami zuwa high - voltage (HV) transmission system, ta haka yana da haske zuwa tsari, kamar kafin inganci, zafi, da kuma adala.
Hankali Da Haske Don Auxiliary Power Supply: Hankalin da haske na auxiliary da station service systems, wanda yana da muhimmanci wajen yin aiki na tsohon karamin gaban karami a cikin ƙananan da zafi.
Tambayar 1 yana nuna misalai na tsarin tsohon karamin gaban karami da ke amfani da maimaita karamin gaban karami don kada karamin gaban karami zuwa main transformer, kuma yana nuna yadda ake amfani da su a cikin tsarin tsohon karamin gaban karami.
Maimaita karamin gaban karami suna da muhimmanci da kayayyaki a cikin tsohon karamin gaban karami, suna da wasu ayyuka mai muhimmanci:
Synchronization with the HV System: Suna da takardun synchronization na karamin gaban karami zuwa system voltage a high voltage (HV) level. Wannan yana ba da huba na cikin kada ilimi na karamin gaban karami zuwa grid, kuma yana taimakawa wajen kada ilimi na karamin gaban karami a kan tsohon karamin gaban karami.
Disconnection from the HV System: Suna da takarda don kada karamin gaban karami daga HV system, wanda yana da muhimmanci idan ake kada unloaded ko lightly loaded generators. Wannan ayyuka yana taimakawa wajen kula tsari na tsohon karamin gaban karami da kuma kudaden ƙananan.
Interruption of Load Currents: Suna da takarda don kada load currents, tun daga full-load current na karamin gaban karami. Wannan ayyuka yana da muhimmanci a cikin aiki na tsohon karamin gaban karami da kuma kudaden ilimi.
System-Fed Short-Circuit Interruption: Suna da takarda don kada system-fed short-circuits, kuma suna hana waƙo karamin gaban karami da wasu abubuwa daga damage na excessive current flow caused by faults in the system.
Generator-Fed Short-Circuit Interruption: Kuma suna da takarda don kada generator-fed short-circuits, kuma suna hana waƙo karamin gaban karami daga internal faults da kuma kudaden ƙananan.
Out-of-Phase Current Interruption: Maimaita karamin gaban karami suna da takarda don kada out-of-phase currents, kuma suna da takarda don manage up to an out-of-phase angle of 180°. Wannan ayyuka yana da muhimmanci wajen kula tsari na tsohon karamin gaban karami a lokacin da aiki na abin da ba.
Synchronization in Pumped Storage Power Plants (Motor Mode): A cikin tsohon karamin gaban karami na pumped storage, idan ake faru karamin gaban karami a motor mode, maimaita karamin gaban karami yana amfani don synchronization na machine zuwa HV system. Akwai wasu methods na synchronization, kamar static frequency converter (SFC) starting ko back-to-back starting.
Handling Starting Current in Pumped Storage Power Plants (Motor Mode): A cikin tsohon karamin gaban karami na pumped storage, idan ake faru karamin gaban karami a motor mode, maimaita karamin gaban karami yana kada da kuma kada starting current, kuma yana ba da huba na cikin faru karamin gaban karami a kan ƙananan.
Low-Frequency Short-Circuit Current Interruption: A cikin tsohon karamin gaban karami na gas turbine, combined-cycle, da kuma pumped storage, maimaita karamin gaban karami suna da takarda don kada generator-fed short-circuit currents at frequencies below 50/60 Hz, kuma suna da takarda don kula tsari na tsohon karamin gaban karami.
Akawo wadanda ake amfani don synchronization a cikin tsohon karamin gaban karami na pumped storage.
Static Frequency Converter (SFC) Starting Scheme: Wannan scheme yana da thyristor converter connected to a unit transformer at the HV side and an inverter linked to the generator. Littafin yana faru karamin gaban karami daga low power frequency to rated power frequency. Idan karamin gaban karami yake produce power, akwai phase angle difference between its output and that of the network. A lokacin da phase difference between the generator and the HV network yake minimize, karamin gaban karami yake synchronize with the HV network using either a generator circuit breaker or an HV circuit breaker.
Back-to-Back Starting Scheme: A cikin tsohon karamin gaban karami da wasu karamin gaban karami, ake amfani back-to-back starting scheme. Ilimi na generator operating under nominal conditions yana amfani don faru generator up to the rated power frequency. Subsequently, the generator is synchronized with the HV network using either a generator circuit breaker or an HV circuit breaker.
Kamar standard IEC/IEEE 62271-37-13, rated short circuit duty cycle na maimaita karamin gaban karami yana nuna two units of operations, with a 30-minute interval between each operation. Duty cycle yana nuna "CO – 30 minutes – CO", wanda yana nuna two complete short circuit interruptions, with a 30-minute gap between each short circuit closing event. Wannan design yana da muhimmanci wajen hana waƙo tsohon karamin gaban karami da karamin gaban karami. Performing two consecutive close-open operations during a full short circuit could potentially cause damage to the generator and the step-up transformers. Such types of short circuits are highly improbable, and it is also very unlikely that a plant manager would attempt to close the circuit again just 30 minutes after a full short circuit event. The 30-minute interval between two operations is essential for restoring the initial conditions of the circuit breaker and preventing excessive heating of its components. It should be noted that this time interval may vary depending on the specific type of operation and the characteristics of the generator circuit breaker.
