Search

Coordination of Directional Over Current Relays (DOCR) is an important issue in the protection of power systems. In this paper, DOCR coordination, which has the problem of nonlinear and high constraints, is discussed The object function, reported in the literature, has been re-written by adding relay setting constraints multiplied by a weight factor to ensure optimum coordination of DOCRs. At first, the Evaporation Rate Controlled Water Cycle Algorithm (ER-WCA) and Harris Hawk Optimization (HHO) algorithms were used to compute the optimum coordination of the DOCR problem. The proposed algorithms are applied to the 9-bus test system. In addition, the results obtained using ER-WCA and HHO were compared with those obtained using other algorithms in the literature. Then, a new adaptive protection method, which adapts to changing power system conditions in power grids with Distributed Generation (DG) system, is proposed. In this new adaptive protection method, the HHO algorithm has been used to ensure optimum coordination of DOCRs. Also, in this new adaptive protection method, a structure with Fault Current Limiting (FCL) mechanism, which determines the critical fault point based on the both of the current and voltage index, is proposed in power systems. Then, by applying this new adaptive protection method to 10 bus Turkey distribution system, the effectiveness of the study was discussed. [ABSTRACT FROM AUTHOR]

Güç sistemleri, üretim aşamasından tüketim aşamasına kadar karmaşık bir yapıdadır. Elektrik enerjisinin tüketiciye sürekli, güvenilir, kaliteli ve ekonomik olarak ulaştırılması üretim/iletim/dağıtım aşamalarında kesintisiz ve optimize edilmiş enerji akışının sağlanmasına bağlıdır. Optimum Yük Akışı (OYA) problemi jeneratörler/bara gerilimleri, kademe değiştiricileri aktif/reaktif gücü güvenli sınırlarında tutup, yakıt maliyeti ve aktif/reaktif güç kayıpları gibi parametrelerini optimize etmeyi hedefler. Bu nedenle güç sistemlerinde OYA probleminin etkili bir yöntemle optimize edilmesi önemlidir. Bu yayın, OYA problemini çözmek için yeni bir sezgisel algoritma olan İyileştirilmiş Su Çevrim Algoritması (İSÇA)'nı kullanmaktadır. Önerilen yöntem farklı amaç fonksiyonlarına sahip IEEE 30 bara güç sistemi üzerinde uygulanmıştır. Önerilen yöntemin etkinliği ve esnekliği literatürde yakın zamanda yayınlanmış diğer sezgisel yöntemlerin sayısal sonuçlarıyla karşılaştırılarak tartışılmıştır. Bu çalışmada İSÇA yöntemiyle IEEE 30 bara güç sistemine ait önemli sonuçlarından biri olan yakıt maliyetinin sonucu 798.9021 $/s hesaplanmıştır. Bu veri, çalışmada bildirilen güncel yöntemlere ait yakıt maliyeti sonuçlarından daha iyidir. Ayrıca bu yayında sunulan yöntem gerçek bir güç sistemi olan 154 kV Güney Marmara iletim sisteminin bir kesitinin sanal modeline uygulanarak, gerçek zamanlı bir sistemde aktif güç kayıplarının azaltılmasının sağlanabileceği gösterilmiştir. Power systems are getting more complex structure from production to consumption stages. The continuous, reliable, quality and economical delivery of electrical energy to the consumer depends on ensuring uninterrupted and optimized energy flow during the production/transmission/distribution stages. Optimum Power Flow (OPF) problem goals to optimize the parameters such as fuel cost, active/reactive power losses, etc by keeping the generators/bus voltages, tap setting and active/reactive power within their secure limits. Therefore, it is important to optimize load flow in power systems with an effective method. This paper uses a recent heuristic algorithm, named as the Modified Water Cycle Algorithm (MWCA), for the OPF problem. For the purpose demonstrate the effectiveness of the recommended method, it has been analyzed on the IEEE 30 bus power system for varied object functions. The validity and flexibility of this algorithm are discussed by comparison with numerical conclusion of the many newly published heuristic methods in the literature. In this study, the result of the of fuel cost, which is important results of the IEEE 30 bus test system, is computed using MWCA as $798.9021/s. This value is best the fuel cost results of various methods reported in the study. In addition, this method, has applied to a part of the virtual model of 154 kV South Marmara transmission system to show that the active power losses of transmission system could be reduced in a realtime system. [ABSTRACT FROM AUTHOR]

In this study, characteristics of three different combi-heaters and heat exchangers were experimentally investigated. All combi-heaters tested have similar technical specifications and have almost the same heat load. Main difference among the combi-heaters is the type of heat exchanger used. Tests were performed for combi heaters containing a combined heat exchanger (K1), a flat plate heat exchanger (K2), double heat exchanger (K3). The objective of this study is to determine the performance of all combi heaters and to determine the benefits and advantages of K1. Performance of all combi heaters were investigated for the heating cycle, domestic water cycle with and without the heating cycle in use, and similarly heating cycle with domestic water in use and finally for different mass flow rates. According to the results of different and parametric experiments for performance evaluation, for the combi heater with combined heat exchanger (K1), advantages in heat transfer characteristics have been detected compared to the other two combi-heaters tested. [ABSTRACT FROM AUTHOR]