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    Day-ahead electricity price forecasting using artificial intelligence-based algorithms
    (Institute of Electrical and Electronics Engineers Inc., 2023) Yorat, Emre; Ozbek, Necdet Sinan; Zor, Kasim; Saribulut, Lutfu
    Deregulation and privatization of electricity markets has brought greater attention to electricity price forecasting (EPF) problem in day-ahead and intraday markets since a reliable forecast ensures market participants develop bidding strategies that aim to maximize their profit. Nonlinear and non-stationary characteristics of electricity prices ensemble a barrier in front of an accurate forecast and have required researchers to analyze the effects of exogenous variables such as economic metrics and neighboring countries' prices. In this paper, three different artificial intelligence-based algorithms namely multiple linear regression (MLR), autoregressive integrated moving average (ARIMA) with exogenous variables, and extreme gradient boosting decision trees (XGBoost) are applied to forecast day-ahead electricity prices of the Turkish electricity market by considering the aforementioned exogenous variables. Test results have shown that the XGBoost model has superior results in the error metrics than the other employed methods. Substantial error decrease in symmetric mean absolute percentage error, normalized root mean square error, normalized mean absolute error, and mean absolute scaled error metrics by 19.256%, 19.834%, 23.060%, and 23.016% is observed with respect to the closest performing MLR method on the test set. © 2023 IEEE.
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    Öğe
    Performance Evaluation of Brushless Direct Current Motor Control Methods through Low-Cost Microcontroller-Based Real-Time Experiments
    (2023) Yorat, Emre; Özbek, Necdet Sinan; Sarıbulut, Lütfü
    Brushless direct current (BLDC) motors are high efficiency synchronous motors that are employed in a variety of applications due to prominent features such as long operational life, low maintenance requirements, and great dynamic response. BLDC motors are driven by energizing the stator windings with an inverter circuit. To commutate the inverter switches, the trapezoidal (120°) method is generally used by considering the back electromagnetic force induced on unenergized phase of BLDC. Furthermore, depending on the application requirements, alternative commutation modes (CM) such as 180°, 150°, and sinusoidal-based approaches are utilized. In the literature, the performance comparison of some CMs was studied for two-phase on operation and three-phase on operation mode by considering the switching patterns. However, only a few research assessed the performance of two or three commutation modes simultaneously. In this study, the performance comparison of pulse width modulation (PWM) based commutation modes are examined by considering 120°, 180°, 150° modes, and sinusoidal PWM. In this scope, it is the first time that direct digital synthesis (DDS) is addressed as a BLDC control algorithm in a performance comparison study. In experimental studies, a simple and a low-cost drive circuit is designed to acquire the case results. According to the results, the proposed DDS-based sine commutation method is more efficient than other commutation methods and it has lower power consumption at both low and high speeds also a wider operable speed range than other applied methods.
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    Öğe
    Sensorless brushless DC motor drive design and performance comparison of different control methods
    (Adana Alparslan Türkeş Bilim ve Teknoloji Üniversitesi, 2022) Yorat, Emre; Sarıbulut, Lütfü; Özbek, Necdet Sinan
    Fırçasız doğru akım motorları (FDAM) yüksek verimlilikleri, yüksek tork/ağırlık oranları, az bakım gerektirmeleri vb. özelliklere sahip olmaları sebebiyle elektrikli ev aletleri, robotik ve elektrikli araçlar gibi birçok uygulama alanında tercih edilmektedir. Bu motorların çalıştırılmaları için elektronik sürücü ve kontrol kartına ihtiyaç duyulur. Bu çalışmada FDAM için L298N H-köprü evireç yapısı ve Atmel mikrodenetleyici ile düşük maliyetli sürücü devresi tasarlanmış ve sensörsüz kontrol algoritması önerilmiştir. Ayrıca 120°, 150° ve 180° komütasyon, doğrudan sayısal sentezleme (DSS) tabanlı sinüzoidal kontrol ve ters-EMK'ya dayalı kontrol yöntemleri benzetim ve deneysel çalışmalarda uygulanmıştır. Yöntemlerin performans karşılaştırması güç kaynağından çekilen akım, dakikadaki devir sayısı ve ağırlık kaldırma kuvveti değerleri açısından gerçekleştirilmiştir. Önerilen yöntemin performansı, uygulanan diğer kontrol yöntemleri içerisinde dikkat çeken sonuçları olan bir yöntemle karşılaştırılarak değerlendirilmiştir. Elde edilen verilere göre, önerilen yöntemle karşılaştırılan yöntemden daha iyi sonuçlara ulaşılmıştır.