• Energy Research

Solar energy is one of the most affordable and clean renewable energy source in the world. Hence, the solar energy prediction is an inevitable requirement in order to get the maximum solar energy during the day time and to increase the efficiency of solar energy systems. For this purpose, this paper predicts the daily total energy generation of an installed photovoltaic system using the Naive Bayes classifier. In the prediction process, one-year historical dataset including daily average temperature, daily total sunshine duration, daily total global solar radiation and daily total photovoltaic energy generation parameters are used as the categorical-valued attributes. By means of the Naive Bayes application, the sensitivity and the accuracy measures are improved for the photovoltaic energy prediction and the effects of other solar attributes on the photovoltaic energy generation are evaluated.

Solar energy is one of the most affordable and clean renewable energy source in the world. Hence, the solar energy prediction is an inevitable requirement in order to get the maximum solar energy during the day time and to increase the efficiency of solar energy systems. For this purpose, this paper predicts the daily total energy generation of an installed photovoltaic system using the Naive Bayes classifier. In the prediction process, one-year historical dataset including daily average temperature, daily total sunshine duration, daily total global solar radiation and daily total photovoltaic energy generation parameters are used as the categorical-valued attributes. By means of the Naive Bayes application, the sensitivity and the accuracy measures are improved for the photovoltaic energy prediction and the effects of other solar attributes on the photovoltaic energy generation are evaluated.

Due to the variations in weather conditions, solar power integration to the electricity grid at a high penetration rate can cause a threat for the grid stability. Therefore, it is required to predict the solar radiation parameter in order to ensure the quality and the security of the grid. In this study, initially, a 1-h time series model belong to the solar radiation parameter is created for multi-period predictions. Afterwards, autoregressive moving average (ARMA) and autoregressive integrated moving average (ARIMA) models are compared in terms of the goodness-of-fit value produced by the log-likelihood function. As a result of determining the best statistical models in multi-period predictions, one-period, two-period and three-period ahead predictions are carried out for the solar radiation parameter in a comprehensive way. Many feasible comparisons have been made for the solar radiation prediction.

Due to the variations in weather conditions, solar power integration to the electricity grid at a high penetration rate can cause a threat for the grid stability. Therefore, it is required to predict the solar radiation parameter in order to ensure the quality and the security of the grid. In this study, initially, a 1-h time series model belong to the solar radiation parameter is created for multi-period predictions. Afterwards, autoregressive moving average (ARMA) and autoregressive integrated moving average (ARIMA) models are compared in terms of the goodness-of-fit value produced by the log-likelihood function. As a result of determining the best statistical models in multi-period predictions, one-period, two-period and three-period ahead predictions are carried out for the solar radiation parameter in a comprehensive way. Many feasible comparisons have been made for the solar radiation prediction.

Abstract In this paper, an improved soft switched two cell interleaved boost AC/DC converter with high power factor is proposed and investigated. A new auxiliary circuit is designed and added to two cell interleaved boost converter to reduce the switching losses. The proposed auxiliary circuit is implemented using only one auxiliary switch and a minimum number of passive components without an important increase in the cost and complexity of the converter. The main advantage of this auxiliary circuit is that it not only provides zero-voltage-transition (ZVT) for the main switches but also provides soft switching for the auxiliary switch and diodes. Though all semiconductor devices operate under soft switching, they do not have any additional voltage and current stresses. The proposed converter operates successfully in soft switching operation mode for a wide range of input voltage level and the load. In addition, it has advantages such as fewer structure complications, lower cost and ease of control. In the study, the transition modes for describing the behavior of the proposed converter in one switching period are described. A prototype with 600 W output power, 50 kHz/cell switching frequency, input line voltage of 110–220 V rms and an output voltage of 400 V dc has been implemented. Analysis, design and the control circuitry are also presented in the paper.

Abstract In this paper, an improved soft switched two cell interleaved boost AC/DC converter with high power factor is proposed and investigated. A new auxiliary circuit is designed and added to two cell interleaved boost converter to reduce the switching losses. The proposed auxiliary circuit is implemented using only one auxiliary switch and a minimum number of passive components without an important increase in the cost and complexity of the converter. The main advantage of this auxiliary circuit is that it not only provides zero-voltage-transition (ZVT) for the main switches but also provides soft switching for the auxiliary switch and diodes. Though all semiconductor devices operate under soft switching, they do not have any additional voltage and current stresses. The proposed converter operates successfully in soft switching operation mode for a wide range of input voltage level and the load. In addition, it has advantages such as fewer structure complications, lower cost and ease of control. In the study, the transition modes for describing the behavior of the proposed converter in one switching period are described. A prototype with 600 W output power, 50 kHz/cell switching frequency, input line voltage of 110–220 V rms and an output voltage of 400 V dc has been implemented. Analysis, design and the control circuitry are also presented in the paper.

Bu calismada, ilk once tek kutuplu bir Yuksek Gerilimli Dogru Akim (YGDA) iletim sistemi modeli olusturulmustur. Bu YGDA iletim sisteminde donusturuculerden kaynaklanan harmonikleri bastirmak icin seri, paralel ve seri-paralel aktif dogru akim filtre tasarimlari gerceklestirilmistir. Tasarlanan bu filtrelerin kullanildigi YGDA iletim sisteminin simulasyonlari MATLAB Simulink’te gerceklestirilmistir. Bu iletim sistemi modelinde filtresiz ve filtreli durumlar icin yuk akiminin ve geriliminin dalga sekilleri ile toplam harmonik distorsiyonu (THD) degerleri elde edilmistir. YGDA iletim sisteminde kullanilan aktif dogru akim filtreleriyle yuk gerilimindeki ve akimindaki harmonikler buyuk oranda bastirilmistir. Ayrica bu akim ve gerilimler icin THD degerleri %5’in oldukca altinda elde edilmistir. Bu sonuclara gore, tasarlanan aktif dogru akim filtrelerinin basit bir yapiya sahip olmasi ve kontrolunun fazla karmasik olmamasi onemli avantajlar saglamaktadir.

Bu calismada, ilk once tek kutuplu bir Yuksek Gerilimli Dogru Akim (YGDA) iletim sistemi modeli olusturulmustur. Bu YGDA iletim sisteminde donusturuculerden kaynaklanan harmonikleri bastirmak icin seri, paralel ve seri-paralel aktif dogru akim filtre tasarimlari gerceklestirilmistir. Tasarlanan bu filtrelerin kullanildigi YGDA iletim sisteminin simulasyonlari MATLAB Simulink’te gerceklestirilmistir. Bu iletim sistemi modelinde filtresiz ve filtreli durumlar icin yuk akiminin ve geriliminin dalga sekilleri ile toplam harmonik distorsiyonu (THD) degerleri elde edilmistir. YGDA iletim sisteminde kullanilan aktif dogru akim filtreleriyle yuk gerilimindeki ve akimindaki harmonikler buyuk oranda bastirilmistir. Ayrica bu akim ve gerilimler icin THD degerleri %5’in oldukca altinda elde edilmistir. Bu sonuclara gore, tasarlanan aktif dogru akim filtrelerinin basit bir yapiya sahip olmasi ve kontrolunun fazla karmasik olmamasi onemli avantajlar saglamaktadir.