نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشجوی کارشناسی ارشد الکترونیک، دانشکده مهندسی برق، دانشگاه علم و صنعت ایران

2 دانشیار دانشکده مهندسی برق دانشگاه علم و صنعت ایران

3 دانشیار دانشکده مهندسی برق، دانشگاه علم و صنعت ایران

چکیده

امروزه در برخی کاربردها به‌ویژه برای نیروگاه‌های خانگی طراحی سیستم‌های فتوولتاییک تک‌فاز متصل به شبکه به سمت استفاده از میکرواینورترها با محدوده توان 150W تا 300W متمایل شده است. هم‌چنین در صنایع دریایی می‌توان از میکرواینورترهای فتوولتاییک به‌منظور تولید بخشی از انرژی الکتریکی مورد نیاز در کشتی‌ها استفاده کرد. در میکرواینورترهای تک‌فاز ضربان با فرکانس دوبرابر فرکانس شبکه روی ولتاژ باس DC وجود دارد که باعث ایجاد هارمونیک در جریان خروجی و کاهش ضریب توان می‌شود. برای کاهش این ضربان اغلب از خازن‌های الکترولیتی با ظرفیت زیاد در باس DC استفاده می‌شود که عیب آن کم بودن طول عمر این خازن‌هاست. برای برطرف کردن این مشکل لازم است خازن‌های الکترولیتی با خازن‌های فیلم نازک که طول عمر زیاد و ظرفیت کمی دارند جایگزین شوند. با کاهش ظرفیت خازن دامنه ضربان ولتاژ باس افزایش می‌یابد و با استفاده از کنترل‌کننده متداول باس (PI) بده‌بستان بین THD جریان خروجی و نوسانات (فراجهش و فروجهش) ولتاژ باس غیرقابل حل است. در این مقاله با به‌کار بردن روش‌های کنترلی پیشنهاد شده میکرواینورتری طراحی و شبیه‌سازی شده است که در آن بدون استفاده از عناصر اضافه این بده‌بستان حل شده است. این میکرواینورتر به شبکه 220V و 50Hz متصل است، در باس آن از خازن با ظرفیت بسیار کم 20µF استفاده شده، در پاسخ به پله 200W توان ورودی، ولتاژ باس آن فراجهش و فروجهش ناچیزی داشته و THD جریان تزریقی آن به شبکه در توان 250W برابر %0.44 است. درستی روش پیشنهادی با شبیه‌سازی در محیط سیمولینک متلب تحقیق شده است.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

A Grid-Connected Single-Phase PV Microinverter With Very Low DC Bus Capacitance, Low THD, and Improved Transient Response

نویسندگان [English]

  • F Bahraini 1
  • Adib Abrishamifar 2
  • A Rahmati 3

1 M.Sc. Student in the School of Electrical Engineering, Iran University of Science & Technoloy (IUST), Tehran, Iran

2 Associate Professor in the School of Electrical Engineering, Iran University of Science & Technology (IUST), Tehran, Iran

3 Associate Professor in the School of Electrical Engineering, Iran University of Science & Technology (IUST), Tehran, Iran

چکیده [English]

Nowadays microinverter with power levels ranging from 150 to 300 W, has become the trend for some grid-connected PV systems specially for residential PV systems. Also, in marine industries, photovoltaic microinverters can be used to produce a part of the electrical energy required on ships. In single phase microinverters there is a double-frequency ripple on the DC bus voltage that causes harmonics and reduces power factor. In order to reduce this ripple, large electrolytic capacitors are often used at the DC bus that the drawback is short lifetime of these capacitors. To overcome this problem, it is necessary to replace electrolytic capacitors with thin film capacitors that have long life and low capacitance. By decreasing the capacitance the amplitude of double frequency ripple on the bus voltage increases so the common bus voltage controller (PI) can’t solve the tradeoff between the output current THD and bus voltage fluctuations (overshoot and undershoot). In this paper, by using the proposed control methods a microinverter is designed and simulated so that this tradeoff has been solved without using additional hardware. This microinverter is connected to the grid (220V, 50Hz). It has a very small 20µF bus capacitor. The bus voltage has negligible overshoot and undershoot in response to a 200W input power step. THD of the injected current to the grid is 0.44% at 250W output power. The effectiveness of the proposed method is validated by simulation results in Matlab-Simulink software.

کلیدواژه‌ها [English]

  • lifetime
  • microinverter
  • photovoltaic (PV)
  • DC bus
  • electrolytic capacitor
  • thin film capacitor

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