Edward Bentley

Impact of electric vehicles on power distribution networks

The market for battery powered and plug-in hybrid electric vehicles is currently limited, but this is expected to grow rapidly with the increased concern about the environment and advances in technology. Due to their high energy capacity, mass deployment of electrical vehicles will have significant impact on power networks. This impact will dictate the design of the electric vehicle interface devices and the way future power networks will be designed and controlled. This paper presents the results of an analysis of the impact of electric vehicles on existing power distribution networks. Evaluation of supply/demand matching and potential violations of statutory voltage limits, power quality and imbalance are presented.

Experimental Demonstration of 50-Mb/s Visible Light Communications Using 4

This letter reports the experimental demonstration of an indoor visible light nonimaging multiple-input multiple-output system with an aggregate error free bit rate of 50 Mb/s over a distance of 2 m. The system uses four independent white LED transmitters, each transmitting 12.5 Mb/s of data in the ON-OFF keying nonreturn zero format, and four independent nonimaging optical receivers. The performance of four detection methods ranging from the basic channel inversion to the more advanced space time techniques is compared experimentally. The results gathered demonstrate that the simplest technique is capable of the same bit error rate as the most complex scheme. The system also provides full illumination with a mean level of 350 Lux satisfying the ISO lighting standards for home and office environments.

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This paper theoretically and experimentally investigate the spectrum attenuation of free space optical (FSO) communication systems operating at visible and near infrared (NIR) wavelengths (0.6 μm <; λ <; 1.6 μm) under fog and smoke in a controlled laboratory condition. Fog and smoke are generated and controlled homogeneously along a dedicated atmospheric chamber of length 5.5 m. A new wavelength dependent empirical model is proposed to predict the fog and smoke attenuation operating at visible and NIR wavelengths. Comparison of the new proposed model with the measured continuous attenuation spectrum from visible-NIR in the fog and smoke channels shows a close relationship than the semi-empirical Kim and Kruse fog models. The experimental results also show the selection for the possible appropriate wavelengths from visible-NIR for FSO links to achieve the maximum link span in dense fog conditions.

4 MIMO

This paper presents a mathematical model for car-to-car (C2C) visible light communications (VLC) that aims to predict the system performance under different communication geometries. A market-weighted headlamp beam pattern model is employed. We consider both the line-of-sight (LOS) and non-line-of-sight (NLOS) links, and outline the relationship between the communication distance, the system bit error rate (BER) performance and the BER distribution on a vertical plane. Results show that by placing a photodetector (PD) at a height of 0.2-0.4 m above road surface in the car, the communications coverage range can be extended up to 20 m at a data rate of 2Mbps.

Modeling of Fog and Smoke Attenuation in Free Space Optical Communications Link Under Controlled Laboratory Conditions

In this paper, we experimentally demonstrate a multiband carrierless amplitude and phase modulation format for the first time in VLC. We split a conventional carrierless amplitude and phase modulated signal into m subcarriers in order to protect from the attenuation experienced at high frequencies in low-pass VLC systems. We investigate the relationship between throughput/spectral efficiency and m, where m = {10, 8, 6, 4, 2, 1} subcarriers over a fixed total signal bandwidth of 6.5 MHz. We show that transmission speeds (spectral efficiencies) of 31.53 (4.85), 30.88 (4.75), 25.40 (3.90), 23.65 (3.60), 15.78 (2.40), and 9.04 (1.40) Mb/s (b/s/Hz) can be achieved for the listed values of m, respectively.

Fundamental analysis of a car to car visible light communication system

Electrical power systems are the backbone of industry, society and current civilisation. Power engineers have accumulated the necessary skills and procedures, to enable them to operate the system in the most reliable way possible. The main principles of system operation have not changed much, despite the rapid developments in power electronics, computing, information and communication technologies. This paper surveys existing power networks and their limits in meeting modern developments and environmental concerns. There is an evaluation of the impacts of deployment of new low carbon technologies such as distributed generation and electric vehicles on existing networks, together with the main drivers for change and features of the new concept of the ‘smart grid’. The paper also examines the challenges and benefits that the ‘smart grid’ will bring, and describes the enabling technologies.

A Multi-CAP Visible-Light Communications System With 4.85-b/s/Hz Spectral Efficiency

In this study, a compact design of a highly efficient, and a high luminosity light-emitting diode (LED)-based visible light communications system is presented, which is capable of providing standard room illumination levels and also wide-coverage Ethernet 10BASE-T optical wireless downlink communications over a distance of 2.3 m using commercial white light phosphor LEDs. The measured signal-to-noise ratio of the designed Ethernet system is >45 dB, thus allowing error-free communications with both on-off keying non-return zero and differential Manchester-coded modulation schemes at 10 Mbps. The uplink has been provided via a wireless infra-red link. A comparative study of a point-to-point wired local area network (LAN) and the optical wireless link confirms no discernible differences between them. The design of the transmitter is also shown to be scalable, with the frequency response for driving 25 LEDs being almost the same as driving a single LED. LED driving units are designed to match with the Ethernet sockets (RJ45) that conform to the existing LAN infrastructures (building and portable devices).

Smart grids: energising the future

Power Quality (PQ) issues are increasingly important owing to the widespread use of power electronic devices, such as switch mode power supply, Electric Vehicle (EV) charging systems, etc. Non linear devices used in EV chargers draw non sinusoidal current and distort the input current from the grid resulting in the injection of Harmonic currents. This paper considers the PQ effects of a number of types of EV charging systems, and examines the effects of multiple instances of such chargers on a simulated network. Some designs will tend to cancel certain harmonics produced by others, and others may magnify the levels of particular harmonics. In addition, the paper explores the ability of the PWM charging system to produce harmonic currents at a chosen phase angle allowing cancellation of particular harmonics.

Experimental demonstration of a 10BASE-T Ethernet visible light communications system using white phosphor light-emitting diodes

The market for electric vehicles (EV) is currently limited, but this is expected to grow rapidly with the increased advances in technology, particularly battery technology. Due to their high energy capacity and potential mass deployment, EVs will have significant impact on power networks. This paper presents a novel, user-friendly modelling tool which uses universally accepted, mathematically robust software to allow analysis of the effects of typical loads, microgeneration and EV charging on the distribution network, mainly the low voltage (LV) feeders, 11/0.4 kV substation and also part of the 11 kV section. Network asset ratings, voltage limits and thermal overloads are determined over a 24 hour period. The model allows the user to input any number of houses, schools, shops, microgeneration and EV charging posts which may be connected at each 400 V node. The EV charging post is modelled using pre-set connection times, battery capacity and battery state of charge (SOC). The effects of different EV battery charging scenarios on the LV network are investigated and presented in this paper. Comparison of different charging regimes demonstrates the effectiveness of the modelling tool and gives guidance for the design of EV charging infrastructure as more drivers choose EVs for their travelling needs.

The interactive effects of multiple EV chargers within a distribution network

Different signal processing techniques are available for automatic detection and diagnosis of power quality disturbances. This paper describes the results of a comparison of the effects of frequency deviation on the accuracy of a number of widely used techniques for signal harmonic analysis, together with a means of mitigation of these effects.