Tambayar da Kula da Ingantaccen Gargaɗi na Inverters a Ƙarfi Duka a Binciken Yadda Ake Tattauna

    Mafi girman inverter (GFM) suna da shawarwari a kan gyara kungiyar zafi a cikin masana'antu mai karfi.  Amma, su ne kadan da dama a kan mafi girman generator da ke gudanar da kungiya a kan abubuwan da ke gudanar da kungiyar zafi.  Don haka, don samun al'amuran da ke gudanar da masana'antu mai karfi a kan matsalolin da ke gudanar da kungiyar zafi, tushen GFM control systems ya kamata yake iya samun abubuwan da na: current magnitude limitation, fault current contribution, da fault recovery capability.  Ana bayyana a cikin littattafan wasu hanyoyi da za su iya samun wannan abubuwa, kamar current limiters, virtual impedance, da voltage limiters.  Wannan takardun ya bayyana halayen hanyoyi.  Duk da cewa ana bayyana muhimman matsaloli da za su iya kasance, kamar temporary overcurrent, unspecified output current vector angle, undesired current saturation, da transient overvoltage.

1.Introduction.

    Kyauka mafi girman inverter (GFM) take taimaka wadanda ake bukatar da shi a kan hanyoyin da ke gudanar da kungiyar zafi. A lokacin da ake rarrabe da matsaloli mai yawa kamar kungiyar zafi ko faɗa a cikin phase a point of common coupling (PCC), mafi girman generator suna iya ba da 5–7 p.u. overcurrent [8], amma mafi girman inverter da ake gudanar da kungiyar zafi suna iya ba da 1.2–2 p.u. overcurrent, wanda ya haifar da su a kan ci gaba da kyaukan kungiyar zafi a cikin harkokin da ba ta shiga matsaloli ba. Current limiters suna taimaka mafi girman inverter a yi aiki a cikin matsaloli a cikin hanyoyin da ke gudanar da kungiyar zafi, wanda ya haifar da su a kan ci gaba da kyaukan kungiyar zafi a cikin hanyoyin da ke gudanar da kungiyar zafi. Amma, virtual impedance methods da voltage limiters suna iya ci gaba da kyaukan mafi girman inverter a cikin hanyoyin da ke gudanar da kungiyar zafi, wanda ya haifar da su a kan ci gaba da automatic fault recovery. Wannan takardun ya bayyana hanyoyin da za su iya samun wannan abubuwa, kamar temporary overcurrent, unspecified output current vector angle, undesired current saturation, da transient overvoltage.

2.   Basics of Current-Limiting Control Methods.

    Wannan takarda ya nuna modeli mai sarrafa da take nuna cikin mafi girman inverter da ke gudanar da kungiyar zafi. Mafi girman inverter na da internal voltage source ve da equivalent output impedance. Filter impedance zai zama a Ze, idan ba a yi inner-loop control ba. Idan a yi inner-loop control, filter impedance bai zama a Ze ba.

3.   Current Limiter.

     Daga hanyoyin da ake amfani da su don ci gaba da saturated current reference i¯ref, an amfani da uku hanyoyin da suka fi sani a cikin mafi girman inverter, kamar instantaneous limiter, magnitude limiter, da priority-based limiter. Bayanan instantaneous limiter ta nuna a Fig.(a), wanda ya amfani da element-wise saturation function don ci gaba da saturated current reference i¯ref. Bayanan magnitude limiter ta nuna a Fig. (b), wanda yana ci gaba da magnitude na original current reference iref. Angle na i¯ref take ci gaba da angle na iref. Fig. (c) ta nuna tsarin priority-based limiter, wanda yana ci gaba da magnitude na iref da kuma yana ci gaba da angle na zuwa ƙarin ƙware-ƙware ϕI. Tabbacin ϕI shine user-defined angle wanda yake nuna angle difference between i¯ref and the d-axis oriented to θ.

4.  Virtual Impedance.

    Hanyoyin virtual impedance wanda take ci gaba da voltage modulation reference da kuma virtual admittance method ta hanyoyin da fast-tracking current control loop suna iya samun shawarwari a cikin ci gaban kungiyar zafi a lokacin da matsaloli mai yawa suka faru. Amma, hanyoyin virtual impedance ta inner-loop control suna ci gaba da kungiyar zafi a cikin hanyoyin da voltage reference vref take iya ci gaba da voltage control loop. Saboda bandwidth na voltage control loop yana da ƙarin, za a iya samun temporary overcurrent. Don haka, hybrid current-limiting methods wanda suka amfani da virtual impedance da priority-based current limiter da kuma current magnitude limiter suna bayyana.

5. Voltage Limiter.

    Voltage limiters suna taimaka ci gaba da voltage difference ∥vPWM−vt∥ ta ƙara da ∥Zf∥IM, wanda take ci gaba da voltage reference generated by the outer-loop control don ci gaba da current magnitude limitation. Wannan hanyoyin shine amsa da ake bayyana saboda ba su sa amsar da adaptive virtual impedance wanda zai iya haifar da system a cikin haliyar da ba ta shiga ba. Don voltage limiters, inner-control loop yana da ƙarin da vPWM=vref. Sannan, equivalent circuit diagram na wannan hanyoyin za a iya tabbatar da shi.