کاهش جریان نشتی در اینورتر فتوولتائیک بدون ترانسفورماتور سه‌فاز با استفاده از روش کنترل پیش‌بین مبتنی بر مدل تک‌برداری و دوبرداری توأم با کمینه‌کردن THD و فرکانس کلیدزنی

نوع مقاله : علمی-پژوهشی

نویسندگان

دانشکده مهندسی - دانشگاه فردوسی مشهد

چکیده

:  امروزه، تقاضا برای سیستم فتوولتائیک به‌دلیل مزایای متعدد آن افزایش یافته است. در بسیاری از کاربردها، به‌منظور کاهش تلفات و در پی آن افزایش بازده، کاهش وزن و هزینه اینورتر، ترانسفورماتورها از اینورترهای فتوولتائیک متصل به شبکه حذف شده‌اند. در این شرایط به دلیل نبود مجزاسازی گالوانیکی، ولتاژ مد مشترک باعث جاری‌شدن جریان نشتی ازطریق خازن پارازیتی می‌شود. جریان نشتی باعث افزایش تلفات، کاهش کیفیت جریان تزریقی به شبکه، ایجاد تداخل الکترومغناطیسی و مشکلات ایمنی فردی می‌شود.
بنابراین بایستی جریان نشتی را تا رسیدن به حدود تعریف‌شده در استانداردVDE0126-1-1 محدود کرد. در مقاله پیش‌رو تلاش شده‌است تا با استفاده از دو روش کنترل پیش‌بین تک‌برداری و کنترل پیش‌بین دوبرداری این کار انجام شود. در این روش بدون به‌کارگیری هرگونه سخت‌افزار اضافی، علاوه بر کاهش جریان نشتی، فرکانس کلیدزنی و مقدار THD جریان شبکه نیز کاهش می‌یابد. نتایج شبیه‌سازی صحت عملکرد روش پیشنهادی را نشان می‌دهد.

کلیدواژه‌ها

عنوان مقاله [English]

Leakage current reduction in a Three-phase Transformerless photovoltaic inverter using the single-vector and double-vector model predictive control systems along with improved THD and switching Frequency

نویسندگان [English]

  • M. Morshedloo
  • R. Ghazi
Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
چکیده [English]

Nowadays the demand for photovoltaic (PV) systems has greatly increased due to their various advantages. In many applications for the purposes of reducing losses, increasing the efficiency and having the lower size and weight the transformer has been removed from the grid connected PV systems. In such situations, due to the absence of the galvanic isolation, the common mode voltage becomes unstable leading to flow of leakage current through the parasitic capacitor. The leakage current increases losses, deteriorates the quality of injected currents, causes the electromagnetic interference and finally presents personal safety problems.
Therefore, it should be reduced to statutory limits which is defined by the VDE0126-1-1 standard. In the present paper attemps have been made to do so, using the single-vecror and double-vector model predictive control (MPCs) systems. In this approach, without using any extra hardware not only the leakage current is reduced, but the switching frequency and the THD index are also simultaneously minimized. The simulation results confirm the superior performance of the proposed method over other valuable methods.

کلیدواژه‌ها [English]

  • Leakage current
  • transformerless inverter
  • predictive control method
  • common mode voltage

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