Showing 13–24 of 66 results
Energy Efficient Green Routing Protocol for Internet of Multimedia Things
Internet of Things (رایگان!
Internet of Things (IoT) envisions the notion of ubiquitous connectivity of ‘everything’. However, the current research and development activities have been restricted to scalar sensor data based IoT systems, thus leaving a gap to benefit from services and application enabled by ‘multimedia things’ or Internet of Multimedia Things (IoMT). Moreover, a crucial issue for Information and Communication Technology (ICT) community is the steer increase in CO2 emissions, which mandates green communication to reduce energy consumption and carbon footprint emissions. Recently, IETF ROLL working group standardized an IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL) for resource constrained devices. RPL builds a tree-like network topology based on some network metric optimization using RPL Objective Functions. Previous RPL implementations for scalar sensor data communication are not feasible for IoMT, since multimedia traffic pose distinct network requirements. The goal of this paper is to design an enhanced version of RPL for IoMT in which the sensed information is essentially provided by the multimedia devices. Our proposed RPL implementation minimizes carbon footprint emissions andenergy consumption, along with the incorporation of application specific Quality of Service requirements. To evaluate the performance of the proposed scheme a simulation study is carried out in Cooja simulator for Contiki-OS, which suggests significant gains in terms of energy efficiency and delay. Index Terms—Internet of Things, Multimedia sensors, Contiki, Green communication, Energy efficiency, RPL.
Energy efficient hybrid adder architecture
An energy efficientرایگان!
An energy efficient adder design based on a hybrid carry computation is proposed. Addition takes place by considering the carry as propagating forwards from the LSB and backwards from the MSB. The incidence at a midpoint significantly accelerates the addition. This acceleration together with combining low-cost ripple-carry and carry-chain circuits, yields energy efficiency compared to other adder architectures. The optimal midpoint is analytically formulated and its closed-form expression is derived. To avoid the quadratic RC delay growth in a long carry chain, it is optimally repeated. The adder is enhanced in a tree-like structure for further acceleration. 32, 64 and 128-bit adders targeting 500 MHz and 1 GHz clock frequencies were designed in 65 nm technology. They consumed 11–18% less energy compared to adders generated by state-of-the-art EDA synthesis tool.
Fuzzy based damping controller for TCSC using local measurements to enhance transient stability of power systems
This paper proposesرایگان!
This paper proposes a local fuzzy based damping controller (LFDC) for thyristor controlled series capacitor (TCSC) to improve transient stability of power systems. In order to implement the proposed scheme, detailed model of TCSC, based on actual behavior of thyristor valves, is adopted. The LFDC uses the frequency at the TCSC bus as a local feedback signal, to control the firing angle. The parameters of fuzzy controller are tuned using an off-line method through chaotic optimization algorithm (COA). To verify the proposed LFDC, numerical simulations are carried out in Matlab/Simpower toolbox for the following case studies: two-area two-machine (TATM), WSCC three-machine nine-bus and Kundur’s two-area fourmachine (TAFM) systems under various faults types. In this regard, to more evaluate the effectiveness of the proposed method, the simulation results are compared with the wide-area fuzzy based damping controller (WFDC). Moreover, the transient behavior of the detailed and phasor models of the TCSC is discussed in the TATM power system. The simulation results confirm that the proposed LFDC is an efficient tool for transient stability improvement since it utilizes only local signals, which are easily available.
High Power Transformerless Photovoltaic Inverter
This paper presentsرایگان!
This paper presents a new topology of high power three-level transformerless photovoltaic inverter (TPVI). It consists of three main circuits; they are a pulse driver circuit, a full bridge inverter (FBI) circuit and a power factor correction (PFC) circuit that have functions as production of pulse waves, to develop alternating current (AC) waveform and to stable voltage of PV array, respectively. To obtain the high power of the TPVI, five FBI circuits are connected in parallel. Each FBI circuit uses MOSFET IRFP460 which has rating current of 20 A, therefore the total FBI circuit has applicable maximum current of 100 A. The high power TPVI is installed in front of Centre of Excellent for Renewable Energy (CERE), Universiti Malaysia Perlis, Northern Malaysia. Its main energy source is a PV array that consists of three unit PV modules are connected in series, each unit has 81 V, 60 W. Some three unit PV modules are connected in parallel to fulfill the demand of high AC power. In this research, an AC three-level waveform of the TPVI is developed and created by a microcontroller PIC16F627A-I/P.
Microgrid operation and management using probabilistic reconfiguration and unit commitment
A stochastic model fرایگان!
A stochastic model for day-ahead Micro-Grid (MG) management is proposed in this paper. The presented model uses probabilistic reconfiguration and Unit Commitment (UC) simultaneously to achieve the optimal set points of the MG’s units besides the MG optimal topology for day-ahead power market. The proposed operation method is employed to maximize MG’s benefit considering load demand and wind power generation uncertainty. MG’s day-ahead benefit is considered as the Objective Function (OF) and Particle Swarm Optimization (PSO) algorithm is used to solve the problem. For modeling uncertainties, some scenarios are generated according to Monte Carlo Simulation (MCS), and MG optimal operation is analyzed under these scenarios. The case study is a typical 10-bus MG, including Wind Turbine (WT), battery, Micro-Turbines (MTs), vital and non-vital loads. This MG is connected to the upstream network in one bus. Finally, the optimal set points of dispatchable units and best topology of MG are determined by scenario aggregation, and these amounts are proposed for the day-ahead operation. In fact, the proposed model is able to minimize the undesirable impact of uncertainties on MG’s benefit by creating different scenarios.
Microgrid Protection Using Communication-Assisted Digital Relays
Microgrids have beenرایگان!
Microgrids have been proposed as a way of integrating large numbers of distributed renewable energy sources with distribution systems. One problem with microgrid implementation is designing a proper protection scheme. It has been shown that traditional protection schemes will not work successfully. In this paper a protection scheme using digital relays with a communication network is proposed for the protection of the microgrid system. The increased reliability of adding an additional line to form a loop structure is explored. Also a novel method for modeling high impedance faults is demonstrated to show how the protection scheme can protect against them. This protection scheme is simulated on a realistic distribution system containing a high penetration of inverter connected Distributed Generation (DG) sources operating as a microgrid. In all possible cases of operation the primary and secondary relays performed their intended functions including the detection of high impedance faults. This system is simulated using Matlab Simulink’s SimPowerSystems toolbox to establish the claims made in this paper.
Modeling of Sediment Management for the Lavey Run-of-River HPP in Switzerland
Reservoir sedimentation hinders the operation of the Lavey run-of-river hydropower plant (HPP) on the Rhone River in Switzerland. Deposits upstream of the gated weir and the lateral water intake reduce the flood release capacity and entrain sediments into the power tunnel. Past flushing operations of the relatively wide and curved reservoir have been inefficient. To improve sediment management, the enhanced scheme Lavey+ with an additional water intake and a training wall for improving flushing was set up. The performance of the enhancement project was tested on a physical model. For its calibration, sediment transport, deposition, and flushing of the present scheme were investigated and compared with prototype measurements. The enhanced scheme was then analyzed in detail to define the flushing discharge and duration, and define the gate operation to ensure maximal erosion of deposits with minimal water loss.
Modified quadrant-based routing algorithm for 3D Torus Network-on-Chip architecture
Due to high performaرایگان!
Due to high performance demands of the consumer electronics and processing systems, like servers, the number of cores is increasing on System-on-Chip (SoC). Networkon-Chip (NoC) is suitable approach for reducing the communication bottleneck of multicore System-on-Chip. With the integration of 3D IC technology, the 3D Network-on-Chip design enhances the execution rate and decreases power utilisation by replacing long flat interconnects with short vertical ones. New compact architectures are possible by arranging the cores in three-dimensions. Optimised routing algorithms can provide higher execution speed along with reduced energy consumption. In this paper an efficient routing algorithm for 3D Torus topology architecture is proposed. A modified quadrant-based routing algorithm for 3D torus NoC architecture is proposed which is primarily based on division of space into different quadrants and also adopting a path which encounters least hops to connect to the destination node. The proposed algorithm is compared with other 3D routing algorithms like XYZ dimension order routing and the simulated results shows that the proposed algorithm has least latency.
New reactive power flow tracing and loss allocation algorithms for power grids using matrix calculation
A novel simple methoرایگان!
A novel simple method is suggested in this paper to evaluate the contributions of the sources (including the generators and branches’ charging capacitances) or the loads to the branches’ reactive flows and losses separately as well as to calculate the sources’ shares in providing the loads’ reactive powers. In the method, the study system is first converted to the system, each branch of which only has reactive loss, using a new technique for modeling the generating branches based on the AC load flow results. The properties of two new matrices (i.e. injection-bus and absorption-bus matrices), which are constituted for theobtained system, are then used to derive three other matrices. These matrices, which express reactivepower productions of the sources in terms of reactive power consumptions of the demands (viz. the loads and branches’ losses) and vice versa, contain the intended contributory factors. Three-bus system is applied to demonstrate the computing process of the method whereas several IEEE systems are used to show its capability to implement on the transmission systems with arbitrary topologies and sizes Some advantages of the method compared to the earlier methods are also illustrated.
Reactive Power Generation Management for the Improvement of Power System Voltage Stability Margin
Voltage stability maرایگان!
Voltage stability margin (VSM) of the power system relates to the reactive power reserves in the network. This paper presents a method to improve the VSM by generator reactive power generation rescheduling. The management of the var generation formulated as an optimization problem and pseudo-gradient evolutionary programming (PGEP) was used to obtain the optimal solution. Modal analysis technique was used to guide the searching direction. Simulation results on the New England 39-bus system demonstrate that the proposed method is effective. Compared with the standard evolutionary programming (SEP), better solution can be obtained, and the convergence speed of the algorithm is improved also. The simulation results show that after the optimal reactive power rescheduling the reactive power reserves of the system is increased and the active/reactive power losses are decreased. The most important advantage is that, the voltage stability margin of power system can be improved without adding new var compensation equipment and changing the active power distribution.