Revista de Sistemas Elétricos e Eletrônicos

Protection of Distributed Generation (DG) is a challenging task in entire electrical family. DG plays a vital role in advanced power systems engineering. The connection of DG to the distribution network has numerous advantages. Even though it has a advantages, while connecting the DG with existing power system network, the fault current level in many places have often exceeded which causes the abnormal conditions in the entire power system network. In order to reduce the fault current level, various Fault Current Limiters (FCL) are proposed. In this paper hybrid Fault Current Limiter (HFCL) and its applications are proposed to minimize the effect of the DG on the distribution protection system in a radial system during a fault. The simulated results are analysed and compared with a Solid State Fault Current Limiter (SSFCL) and Superconducting Fault Current Limiter (SFCL) using MATLAB simulation. The effectiveness of proposed fault current limiters are determined and examined in the test system.

Power System planning encompasses the concept of minimization of transmission losses keeping in mind the voltage stability and system reliability. Voltage profile decides the state of a system and its control is dependent on Generator source voltage, shunt/series injection, transformer taps etc. Optimal parameter setting in system level is needed for managing the available resources economically. This paper presents the use of Firefly and Spiral optimization as novel schemes for minimizing the active power loss along with partial compensation of inter bus voltage drop. The objective function has been evaluated under both static and dynamic loading conditions. The control variables being generator bus voltage, capacitor shunts and transformer taps. These methods were employed in an IEEE 6-bus system and the results were tabulated.

In this paper an IEEE standard test system has been considered and Load flows were computed by using Newton- Raphson method with the help of MATLAB and a weak bus is identified. The bus that is with a low voltage magnitude is incorporated with FACTS devices namely TCSC and SVC in order to improve the voltage under normal conditions. Then the reactive power at a particular bus is increased until it reaches to the instability point and the voltage stability condition is evaluated by using an L-index method. The values which approach unity imply that it reaches to instability, and corresponding bus can be treated as weak bus i.e. with a highest value of L-index, and is incorporated with FACTS devices to enhance the voltage stability under post-fault steady state condition also.

Results of experimental investigations into the possibility of a pulsed inductive cylindrical discharge as a new method of pumping gas lasers operating at different transitions of atoms and molecules with different mechanisms of formation of inversion population are presented. The excitation systems of a pulsed inductive cylindrical discharge (pulsed inductively coupled plasma) in the gases are developed and experimentally investigated. For the first time five pulsed inductive lasers on the different transitions of atoms and molecules are created. Characteristic feature of the emission of pulsed inductive lasers is ring-shaped laser beam with low divergence and pulse-to-pulse instability is within 1%.

An open challenge in trustworthy computing is the development of a trustworthy network since network plays an essential role of current computing infrastructure (e.g., grid computing, cloud computing, etc.). In order to have a trustworthy network, security, privacy, and reliability must be protected on every major network component. For instance, if there is no trusted mechanism to enforce security protection of every data transaction on major network components, a network cannot be relied on performing trustworthy computing. It has been observed that trustworthy network cannot be practically achieved if there is no trusted integration of major network components. In this paper, we discuss the challenges in building a trustworthy network and develop a trustworthy network model that is both scalable and interoperable with existing and future network architectures.

Network traffic traces provide valuable information for researchers to study behaviors of normal and malicious network activities. Although traffic traces are enough to reveal packet-level and connection-level details of most network activities, identifying specific malicious network activities is still a huge challenge: many malicious network activities are able to hide themselves behind normal activities with forged packet and connection information. In practice, mechanisms that are able to effectively extract malicious network activities from raw traffic traces are emerging and will benefit network security and other related communities as well. In this paper, a fluid-based approach for modeling simulated normal and malicious flooding-based denial of service network activities is developed. To approach this goal, several raw traffic traces gathered by the Cooperative Association for Internet Data Analysis (CADIA) are analyzed and investigated.

Nonideal 1D photonic crystal is modeled as a macroscopically homogeneous layered system (which is onedimensional Si-liquid crystal superlattice with two elements-layers in the cell) with randomly included admixture layers. The virtual crystal approach which is the method to describe quasi-particle excitations in disorder media is used. Peculiarities of the dependence of photonic band gap width on admixture layers concentration have been studied. The results are the evidence of substantial polariton spectrum reconstruction caused by presence of defect layers.

Inflection point detection is an important yet challenging problem in science and engineering. This paper addresses the estimation of a single inflection point location in noisy observations using non-parametric polynomial regression. To address the bandwidth problem, a constrained approach is proposed to ensure having a single inflection point, thereby reducing the uncertainty in the inflection point location whereas being flexible on the shape of the underlying signal. The performance of the proposed method is evaluated through simulations. It is shown that the proposed method can effectively estimate the inflection point under high noise conditions.