A. Jrad

Comparison of fully distributed and periodically loaded nonlinear transmission lines

Two different approaches to realizing nonlinear transmission lines (NLTLs) are investigated in detail. In the first approach, the nonlinearity is continuously distributed along the line; in the second, the line is periodically loaded (PL) with discrete nonlinear elements. Measured heterostructure-barrier varactor (HBV) characteristics are used as the nonlinearities in both pulse-compression and harmonic-generation (20-60-GHz tripler) simulations. We point out that the choice of simulation step size is critical in the case of fully distributed (FD) NLTLs, and should be made sufficiently small that no numerical Bragg cutoff frequency appears. For the frequency tripler considered in this paper, simulations show that with PL (PL) NLTLs, 21% efficiency at 210-mW output power and 30% bandwidth can be obtained, whereas only 4.8% efficiency is possible using FD NLTLs. For pulse compression, we find that when properly matched, the FD NLTLs can deliver pulses that are five times sharper than can be obtained with the PL NLTLs. Measured results for an HBV-based PL NLTL frequency multiplier are reported that agree with our simulations, in particular, the 30% bandwidth. The confirmation of the role of the Bragg cutoff frequency in preventing the generation and propagation of undesired harmonics (this improving the conversion efficiency) is obtained from experimental results carried out from hybrid Schottky diodes NLTL measurements.

A cooperative aggregation-based architecture for vehicle-to-grid communications

In the future Intelligent Transportation Systems, vehicles will be equipped with special units giving them the capacity to communicate wirelessly. Furthermore, electric vehicles are expected to take a bigger part of the market in the future. Global preoccupations to reduce carbon emissions and stimulate the use of renewable and sustainable energies have motivated the concept of vehicle-to-grid power, which integrates the electric vehicles within the smart grid (the electricity network of the future). The vehicle-to-grid vision aims to take advantage of these battery equipped vehicles, using them as a storage device for intermittent energy sources, and as a power resource to provide ancillary services to the power grid. This paper focuses on the architectural needs of such a system, specifically at the communications level. It also presents an agent-based model for an aggregative system for vehicle-to-grid communications. The agent-based approach will allow the distributed architecture to benefit from a variety of well-established communication and cooperation mechanisms and methods that can be applied to the vehicle-to-grid concept.

An Agent-Based Approach for Energy Management in Smart-Grids

The advances in Information and Communication Technologies (ICT) permits interactions among the computational and the physical elements of the smart-grid, and provide opportunities for novel energy management techniques allowing thus renewable energy integration and energy price minimization. Few of the current energy management schemes integrate storage aspects. In this paper, we propose an agent-based algorithm for better energy management in the smart-grid using a storage system. Furthermore, we propose a negotiation algorithm to help consumer choose the appropriate producer which provides him the needed energy at the lowest price. Simulation results show that our proposal minimizes the energy costs for each energy demand and reduces conventional energy utilization.

Full Study of the Parallel-Coupled Stub-Loaded Resonator: Synthesis Method in a Narrow Band With an Extended Optimal Rejection Bandwidth

This paper gives a complete theoretical study in a narrow band for the parallel-coupled filters based on short-circuited stub-loaded resonators. It describes a synthesis method for this filter topology, and a complete resonant mode analysis to fully control the spurious frequencies positions. To enlarge the out-of-band rejection, an original technique, based on simple design steps, is used to address tuning of extra transmission zeros. Harmonic was suppressed to better than 35 dB with a wide stopband of more than six time the fundamental frequency. Design equations and design rules are given. Finally, several three-pole bandpass filters are designed and characterized in stripline and miscrostrip technologies to demonstrate the efficiency of the proposed concepts.

A simple and systematic method for the design of tapered nonlinear transmission lines

In this paper, we present an original method, simple to implement, rapid and systematic for the conception of Nonlinear Transmission Lines (NLTL) for shock wave generation. This method is based on SPICE simulations and allows the synthesis of hybrid or monolithic NLTLs.

Synthesis method for the parallel-coupled stub-loaded resonator filters

This paper describes a synthesis method for parallel-coupled filters based on short-circuited stub-loaded resonators. Synthesis formulas were derived for homogeneous medium. Simulations are presented to validate the theory for three relative bandwidths 2, 4 and 8 %. For a proof-of-concept a third-order stripline bandpass filter was designed with a passband ripple of 0.01 dB and a relative bandwidth of 4.5%. Theory, simulations and measurements are in good agreement and thus validate the theory.

Enhancing smart grid operation by using a WSAN for substation monitoring and control

One of the main preoccupations of the next generation power network, i.e. the smart grid, is improving the reliability of the power network. In order to achieve that, monitoring and control applications play an important role, in particular at a substations level. Using a wireless sensor and actuator network is an attractive option for these applications. However, what is missing so far is that information collection should be complemented with the ability to transform significant data into actions in a decentralized manner. In this paper, we address this issue by adopting an agent-based approach. Autonomous agents are embodied in sensor nodes in order to evaluate the importance of collected data and choose an appropriate communication policy. In order to evaluate each phase of the proposed algorithm, different variants are compared with the legacy client/server scheme. Simulation results have shown better performance in terms of network congestion, energy consumption, and transmission delay.

Putting Sensor Data to the Service of the Smart Grid: From the Substation to the AMI

One of the requirements of a smart grid (SG) is making the electrical network and its subsystems aware of their condition. The deployment of various sensing devices plays an essential part in achieving this goal. Nevertheless, data generated by this deployment needs to be well managed so that it can be leveraged for operational improvement. Data aggregation is perceived as an important technique for managing data in the SG in general, and in its Advanced Metering Infrastructure (AMI) in particular. Indeed, data aggregation techniques have been used in order to reduce communication overhead in SG networks. However, in order to fully take advantage of the aggregation process, some level of intelligence should be introduced at concentrator nodes to make the network more responsive to local conditions. Moreover, by using a more meaningful aggregation technique, entities can be accurately informed of any disturbance. This paper contributes an agent-based approach for data and energy management in an SG. It also proposes CoDA, a correlation-based data aggregation technique designed for the AMI. CoDA employs fuzzy logic to evaluate the correlation between several messages received from Smart Meters (SMs). Analysis and simulation results show the benefits of the proposed approach w.r.t. both packet concatenation and no aggregation approaches.

FDTD and SPICE Simulations for Lossy and Dispersive Nonlinear Transmission Lines Used for Pulse Compression : a Comparison

For the first time, we demonstrate the simulation of lossy and dispersive non linear transmission lines (NLTLs) used for pulse compression, by two different time-domain approaches: SPICE and a full wave 3D FDTD. Results show a good agreement between the two approaches. Output pulse risetime is very affected by DC and skin-effect losses.

A combination of transformation optics and surface impedance modulation to design compact retrodirective reflectors

This study proposes a new approach to flatten retrodirective corner reflectors. The proposed method enables compact reflectors via Transformation Optics (TO) combined with Surface Impedance Modulation (SIM). This combination permits to relax the constraints on the anisotropic material resulting from the TO. Phase gradient approach is generalized to be used within anisotropic media and is implemented with SIM. Different reflector setups are designed, simulated and compared for fop = 8GHz using ANSYS® HFSS® in order to validate the use of such a combination.