Recent Advances in Communications and Networking Technology (Formerly Recent Patents on Telecommunication) (Discontinued) - Volume 4, Issue 2, 2015

In Germany due to the continuous high expansion of the intermittent power supply capabilities of wind turbines and photovoltaic systems, the operational modes of thermal generation units will be influenced essentially until 2020 and beyond. With the renewable energy sources (e.g. wind power (WP) and photovoltaic (PV)) in power system increase, the conventional power plants on line will be replaced by WP and PV. Thus, the sources of conventional reserve available to the system will be reduced and fewer conventional plants will be available online to share the regulation burden. Therefore the acceleration time constant is reduced if some of the conventional power plant generators with inertia (masses) are disconnected and replaced by the intermittent generators while the total nominal power value of the whole system remains constant. With the reduction of inertia not only the frequency deviation after disturbances will increase substantially but also more oscillation occurs which causes reduction in system stability. Therefore different scenarios of Renewable Energy sources will be presented and for the investigation of the system stability influenced by the primary control of the remaining conventional power plants the following mathematical methods are useful and have been used nonlinear dynamic simulation andl inear eigenvalue calculation. The models were created using MATLAB / Simulink software.

There has been a rapid increase in wind turbine connection to distribution and transmission networks in recent years. With individual wind turbines approaching the multi - MW and the wind plants, as a result, approaching the output rating of conventional power plants, a deeper understanding of their potential impacts on interactions with the bulk electric power system is needed. The increased penetration makes the power network more dependent on, and susceptible to, the wind energy production. As the wind power penetration into the grid increases rapidly, the influence of wind turbines on the power quality and voltage stability is becoming more important. The main objective of this study is to analyze the voltage stability of the Egyptian Electrical Network with large scale wind power under normal operation and under single contingency (N-1). The single contingency is defined as the loss of any transmission line, transformer, or generator. In addition, the paper determines the size of reactive power compensation devices (capacitors or STATCOM) that should be installed at weak buses to prevent the voltage collapse.

HIFs can remain masked and undetected by classical ground and current based relays for long periods of time, causing high risk of injury to surrounding wildlife and personnel. One of the hardest and complex problems facing nowadays is the detection of high impedance faults on electrical distribution systems. This paper presents a classification and detection relaying scheme for fast accurate detection and identification of linear and nonlinear arc type high impedance (HIF) faults on a meshed distribution system. The proposed method uses the Fast Fourier Transform and examines the properties of the auto and cross spectra of the lower order dominant harmonics to differentiate between several fault types. This is particularly necessary in the case of high impedance HIF-fault detection. The proposed smart relay is simulated and validated at different fault locations along the distribution feeder to ensure a robust and correct identification of linear and arc type nonlinear faults. Fault models are built for five common fault types. The low order transients are examined for each different fault type and a smart relay is designed which is capable to classify each of the different faults. The simulation results show that the proposed arc type detection relay is capable of successfully classifying each of the five different distinct possible faults at any feeder fault location and even in the presence of different source phase shift on the distribution meshed network.

Integration of photovoltaic (PV) energy into the electrical power system is increasing with the development in the PV technology. Transformer magnetizing inrush current problem occurs due to switching the trans-former into the service. This paper proposes an inrush current reduction technique using the PV power. The proposed procedure applies an opposite flux on the transformer using the PV power, then connect the trans-former with the electrical power network at a suitable instant of the grid voltage waveform. The switching in-stant depends upon the flux produced in the transformer primary winding by the PV system. The proposed procedure is applied on a single phase system and simulated in MATLAB R2012a/SIMULINK. The simula-tion results illustrate the suitable instant of switching to reduce the magnetizing inrush current and the corre-sponding total harmonic distortion (THD).

This paper presents the architecture, functionality, and field evaluation of a newly developed real-time advanced warning system using dedicated short range communication (DSRC) based vehicle-to-vehicle (V2V) communication without the need for a DSRC roadside unit to control the system operation. The developed system dynamically acquires important traffic parameters such as starting location of congestion (SLoC), ending location of congestion (ELoC) and travel time (TT), and provides useful traffic alerts in real time to improve drivers’ situational awareness. The newly developed system utilizes an ad-hoc host vehicle selected from among the DSRC equipped vehicles present on the road, to act as central controller for acquisition and dissemination of traffic parameters. The ad-hoc host is selected by detecting the deceleration speed profiles of several DSRC equipped vehicles that are about to enter the back-of-the-queue. The selected ad-hoc host then acquires a new set of traffic parameters, as well as broadcasts useful alerts to vehicles trailing far behind the back-of-thequeue. The algorithm presented here makes it fully adaptable to any congestion scenario whether due to a work zone, an incident, or due to regular rush hour traffic. The developed system is well suited for operational deployment, particularly during the initial phase of the DSRC market penetration, because it only needs 15- 25% of DSRC market penetration to acquire traffic parameters. The proposed system also incorporates DSRC equipped programmable changeable message signs (PCMSs) to convey the warning messages to non-DSRC equipped vehicles.

This work presents a patent technique for digital image compression using wavelet theory and a Huffman CODEC system that can be used for bandwidth reduction in digital transmission and to decrease time of data transmission in channel information. A twodimensional 1-channel multiresolution analysis and synthesis structure are implemented. In the transmission, the digital image is processed using quincunx lowpass filtering and quincunx downsampling, iteratively, in the analysis part, followed by a Huffman encode, in order to make easy the binary code ordering and to set it for transmission in channel information. Once binary code is set, it can be sent through a transmission channel. In the reception, the digital subimage is Huffman decoded and then submitted to the synthesis process, using quincunx upsampling and quincunx lowpass filtering, multiplying the resulting image by |det Mq|, iteratively, in order to get the digital image perfect reconstruction. The major contributions of this work are the high rates of compression at the end of decomposition process, the facility of Huffman codec implementation, comprising the encoding part, the arrangement of the image vector in the last level, setting it for fast digital transmission through an information channel and the Huffman decoding part. And finally, the efficiency of the digital images perfect reconstruction. Simulations using “MATLAB” were developed with digital images in multiresolution, from the first level until to reach the vector image (last level) in the decomposition part and similarly, from the last level until to reach the first level, in the image synthesis part (reconstruction). Three different images, with different gray levels distributions were used as information source. The images are monochromatic, 8-bits and their dimensions are 1024x1024 (Saturn rings), 512x512 (Lena) and 128x128 (Saturn).