بهبود پایداری گذرای مبدل متصل به شبکه هنگام افت ولتاژ شدید با تکنیک امپدانس مجازی
الموضوعات :
امید عبدلی
1
(دانشگاه اصفهان)
مهدی قلی‌پور
2
(دانشگاه اصفهان)
رحمت‌الله هوشمند
3
(دانشگاه اصفهان)
الکلمات المفتاحية: امپدانس مجازی, PLL, مبدل متصل به شبکه, پایداری گذرا, افت ولتاژ,
ملخص المقالة :
با افزایش نفوذ منابع تولید پراکنده مبتنی بر اینورتر، دستورالعمل‌های شبکه خواستار عدم قطع این مبدل‌ها از شبکه هنگام رخداد خطا می‌باشند. این مبدل‌ها همچنین می‌بایست با تزریق توان راکتیو به رفع خطا کمک کنند. از آنجایی که شبکه‌های برق سلفی خالص نبوده و دارای مقاومت اهمی نیز هستند، این شبکه‌ها هنگام رخداد خطا با مشکل ناپایداری مبدل روبه‌رو می‌شوند. مبدل‌ها که جهت سنکرون‌ماندن با شبکه از حلقه قفل فاز (PLL) استفاده می‌کنند، هنگام رخداد خطای افت ولتاژ سنگین، دیگر قادر به حفظ پایداری با شبکه نیستند. در نتیجه این مبدل‌ها قادر به گذر از خطا نبوده و می‌بایست از شبکه جدا شوند. این مقاله با ارائه روشی جدید مبتنی بر امپدانس مجازی در هنگام رخداد افت ولتاژ سنگین، پایداری سنکرون با شبکه برق را حفظ می‌کند. این روش نیاز به تخمین تقریبی امپدانس شبکه دارد و مبدل را مجازاً با نقطه‌ای که اتصال قوی‌تری دارد سنکرون می‌کند. با استفاده از روش پیشنهادی در هنگام افت ولتاژ، مبدل به شبکه متصل مانده و می‌تواند به شبکه توان راکتیو تزریق کند. نتایج شبیه‌سازی با استفاده از نرم‌افزار Matlab درستی روش پیشنهادی برای بهبود پایداری گذرای مبدل را نشان می‌دهد.
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