Elektrik enerjisinin kesintisiz ve kaliteli bir şekilde iletilmesi için, üretim yapıldığı noktadan tüketim olan noktaya kadar kontrol edilmesi gerekmektedir. Dolayısıyla üretimden tüketime kadar her aşamada iletim ve dağıtım hatlarında koruma yapılması şarttır. Elektrik tesislerinde koruma rölelerinin temel görevi, sistemde meydana gelen kısa devrelerde arızalı olan bölgenin mümkün olan en kısa sürede devre dışı etmektir. Sistemin en önemli parçası olan enerji iletim hatları ve bu hatları koruyan mesafe koruma rölelerine bu konuda çok önemli görevler düşmektedir. Hızlı ve verimli çalışmalar yapmak için doğru bir hata yeri tespit tekniği gereklidir. İletim hatlarında transformatör nötr nokta topraklaması bir güç sisteminin tek faz-toprak kısa devre arızası sırasında oluşan sıfır bileşen akımı mesafe koruma rölesinin çalışmasını etkilemektedir. Topraklama sistemi ve koruma sistemleri arasındaki ilişki göz önüne alındığında, uygun bir topraklama seçimi yapılmalıdır. İletim hatlarında farklı topraklama sistemlerinde kısa devre arızalarının yerinin doğru bir şekilde belirlenebilmesi için yapay sinir ağı (YSA) kullanılmıştır. YSA'nın performansını test etmek için destek vektör makineleri (DVM) ile karşılaştırılmıştır. İletim hattı modeli PSCAD ™ / EMTDC ™ benzetim programında oluşturulup YSA için gerekli veriler elde edilmiştir. Farklı topraklama sistemlerinde oluşturulan kısa devre arızalarındaki mesafe koruma rölesinin R-X empedans diyagramının empedans değişiminin görüntüsü kayıt altına alınarak veri setleri oluşturulmuştur. Görüntülerde ilgili odak noktaları özellik çıkarım ve görüntü işleme teknikleri kullanılarak farklı YSA modellerine giriş olarak verilmiş ve en iyi arıza yeri tahmini veren YSA modeli seçilmiştir.

Overhead lines are generally used for electrical energy transmission. Also, XLPE underground cable lines are generally used in the city center and the crowded areas to provide electrical safety, so high voltage underground cable lines are used together with overhead line in the transmission lines, and these lines are called as the mixed lines. The distance protection relays are used to determine the impedance based fault location according to the current and voltage magnitudes in the transmission lines. However, the fault location cannot be correctly detected in mixed transmission lines due to different characteristic impedance per unit length because the characteristic impedance of high voltage cable line is significantly different from overhead line. Thus, determinations of the fault section and location with the distance protection relays are difficult in the mixed transmission lines. In this study, 154 kV overhead transmission line and underground cable line are examined as the mixed transmission line for the distance protection relays. Phase to ground faults are created in the mixed transmission line. overhead line section and underground cable section are simulated by using PSCAD/ EMTDC ™. The short circuit fault images are generated in the distance protection relay for the overhead transmission line and underground cable transmission line faults. The images include the R-X impedance diagram of the fault, and the R-X impedance diagram have been detected by applying image processing steps. Artificial neural network (ANN) and the regression methods are used for prediction of the fault location, and the results of image processing are used as the input parameters for the training process of ANN and the regression methods. The results of ANN and regression methods are compared to select the most suitable method at the end of this study for forecasting of the fault location in transmission lines.

Overhead lines are generally used for electrical energy transmission. Also, XLPE underground cable lines are generally used in the city center and the crowded areas to provide electrical safety, so high voltage underground cable lines are used together with overhead line in the transmission lines, and these lines are called as the mixed lines. The distance protection relays are used to determine the impedance based fault location according to the current and voltage magnitudes in the transmission lines. However, the fault location cannot be correctly detected in mixed transmission lines due to different characteristic impedance per unit length because the characteristic impedance of high voltage cable line is significantly different from overhead line. Thus, determinations of the fault section and location with the distance protection relays are difficult in the mixed transmission lines. In this study, 154 kV overhead transmission line and underground cable line are examined as the mixed transmission line for the distance protection relays. Phase to ground faults are created in the mixed transmission line, and overhead line section and underground cable section are simulated by using PSCAD/ EMTDC ™. The short circuit fault images are generated in the distance protection relay for the overhead transmission line and underground cable transmission line faults. The images include the R-X impedance diagram of the fault, and the R-X impedance diagram have been detected by applying image processing steps. The regression methods are used for prediction of the fault location, and the results of image processing are used as the input parameters for the training process of the regression methods. The results of regression methods are compared to select the most suitable method at the end of this study for forecasting of the fault location in transmission lines. When looking at the method and performance criteria used in the overhead transmission line fault location study, it is the Linear Regression (Robust Linear) method that gives the most accurate results with RMSE 0.017652. When looking at the method and performance criteria used in the underground cable transmission line fault location study, it is the Linear Regression (Stepwise Linear) method, which gives the most accurate results with RMSE 0.0060709. When the accuracy of the method was examined, it was seen that it was higher than other methods.

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