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Inverter-based resources respond differently than synchronous generation sources during power system faults, challenging line protection reliability. Part I of this paper presented cases that challenge line protection schemes. In this paper (Part II), we provide solutions that can be applied to gain a substantial improvement in reliability. [ABSTRACT FROM AUTHOR]

Inverter-based resources respond differently than synchronous generation sources during power system faults, challenging line protection reliability. To understand the reliability challenges, Sandia National Laboratories and North American Electric Reliability Corporation (NERC) led a collaborative study with four inverter manufacturers (mix of Type 3 Wind, Type 4 Wind, and PV Solar) and two North American protective relay manufacturers. As part of this study, an electromagnetic transients program (EMTP) with “real-code” models representing inverter firmware was used to investigate the protective relay response to faults on the modeled power system with the different inverter types. The currents and voltages obtained from the study were then played back through line relay hardware with settings typical of systems with conventional generation. The protective relays exhibited the expected reliability challenges but provided insight into the behavior of inverter-based resources during power system faults. In this paper, we share some of the challenging cases with the responses of the different line protection schemes. Using insight from the various event records, Part II of this paper shows how relay settings can be modified to obtain a substantial improvement in reliability. [ABSTRACT FROM AUTHOR]

A one-eighth spherical surface dielectric resonator antenna (OESS-DRA) is proposed first time. To analyze this thin shell structure, electromagnetic fields distribution is discussed by using the Hertz vector and boundary conditions. We simplify the solution of Maxwell equations by using Hertz vector because the polarization current is primary in the OESS-DRA. The Hertz vector can be expressed the current better. This proposed antenna is composed of one-eighth spherical dielectric shell fed by coaxial probe; and the ground with metal-corner-reflector makes the antenna with high gain and directional radiation properties. To verify this design, a fabricated sample is tested; results show the antenna covering bandwidth 4.56-6.88GHz, a high gain greater than 9.5dBi (peak gain 11.8dBi at 5.0GHz), and a high radiation efficiency over 85% in the entire working frequency band, as well. The OESS-DRA can be a good candidate in 5th generation communication applications.

A directional two-element mm-wave dipole antenna array with reconfigurable patterns is presented in this paper. An substrate integrated waveguide (SIW) 90° coupler is used to realize reconfigurable patterns of the antenna array. The two dipole elements are parallel in space, and there is a distance of λ0/4 (λ0 is the wavelength of the free space) between them. When the two inputs of the 90° coupler are excited, respectively, two completely opposite radiation patterns are able to be achieved. In order to further enhance the directivity of the proposed antenna, two groups of novel zero-index metamaterials and three metallic strips are introduced. As a consequence, a 0.7-1.2 dBi gain enhancement and reduced back lobe are obtained within the working frequencies. The measured amplitudes of S11 and S22 are below -10 dB from 45.5 to 49.5 GHz, and the measured gain is all great than 5 dBi within this band.

A directional slot antenna with a squared arch structure for Wi-Fi applications is proposed in this communication. In general, one antenna can hardly obtain a nonsplitting and relatively consistent radiation beam in both the 2.4 and 5 GHz bands. A relatively consistent horizontal beamwidth in the dual bands is desired to maintain the same sector signal coverage and avoid interfering with adjacent sectors to maximize the data transmission in usage scenarios such as a sports stadium and warehouse. With a squared arch design, the proposed slot antenna can keep the H-plane beamwidth relatively the same in the dual bands. The slot antenna achieves good matching in both the 2.4 (2.4–2.5 GHz) and 5 GHz (4.9–5.9 GHz) bands, and good vertical polarization. An expression describing the condition of generating a nonsplitting beam is derived as a function of the source spacing, and can be used to guide the arch design. Finally, the proposed slot antenna with the squared arch structure is validated by both simulations and measurements of a prototype. [ABSTRACT FROM AUTHOR]

This paper presents a compact 0.92/2.45-GHz dual-band directional circularly polarized (CP) microstrip antenna for handheld radio-frequency identification (RFID) reader applications. The proposed antenna comprises a wideband dual-feed network and two stacked concentric patches assembled by two orthogonally placed vertical probes. The dual-feed network feeds quadrature signals across the RFID bands between 0.92 and 2.45 GHz. The two stacked concentric patches provide resonance frequencies in fundamental mode for lower band and higher band, respectively. Additionally, the antenna features only one connection port and same sense CP radiation at two bands, beneficial to cost and complexity reductions of the dual-band front end of RFID readers. The measurement results show the performances of return loss (RL) > 10\;\textdB, 3-dB gain variation, and axial ratio (AR) < \text3\;\textdB are achieved on the bands 0.911–0.933 GHz and 2.40–2.57 GHz. The measured peak gains are 3.8 dBic at 0.926 GHz and 8.9 dBic at 2.48 GHz. In addition, the antenna provides symmetrical patterns with wide-angle half-power beamwidths and wide-angle 3-dB AR beamwidths. The size of the antenna \text110 \times \text110 \times \text6.6\;\textm\textm^\text3 is much smaller than reported dual-band one port RFID directional CP reader antennas. The antenna appropriates to both ultra-high frequency (UHF) and industrial scientific and medical (ISM) bands in handheld RFID reader applications. [ABSTRACT FROM PUBLISHER]

Network diagnosis is crucial in managing a wireless sensor network (WSN) since many network-related faults, such as node and link failures, can easily happen. Diagnosis tools usually consist of two key components, information collection and root-cause deduction, while in most cases information collection process is independent with root-cause deduction. This results in either redundant information which might pose high communication burden on WSNs, or incomplete information for root-cause inference that leads false judgments. To address the issue, we propose DID, a directional diagnosis approach, in which the diagnosis information acquirement is guided by the fault inference process. Through several rounds of incremental information probing and fault reasoning, root causes of the network abnormalities with high credibility are deduced. We employ a node tracing scheme to reconstruct the topical topology of faulty regions and build the inference model accordingly. We implement the DID approach in our forest monitoring sensor network system, GreenOrbs. Experimental results validate the scalability and effectiveness of this design. [ABSTRACT FROM AUTHOR]

We introduce a series of geographically weighted (GW) interactive graphics, or geowigs, and use them to explore spatial relationships at a range of scales. We visually encode information about geographic and statistical proximity and variation in novel ways through gw-choropleth maps, multivariate gw-boxplots, gw-shading and scalograms. The new graphic types reveal information about GW statistics at several scales concurrently. We impement these views in prototype software containing dynamic links and GW interactions that encourage exploration and refine them to consider directional geographies. An informal evaluation uses interactive GW techniques to consider Guerry's dataset of 'moral statistics', casting doubt on correlations originally proposed through visual analysis, revealing new local anomalies and suggesting multivariate geographic relationships. Few attempts at visually synthesising geography with multivariate statistical values at multiple scales have been reported. The geowigs proposed here provide informative representations of multivariate local variation, particularly when combined with interactions that coordinate views and result in gw-shading. We argue that they are widely applicable to area and point-based geographic data and provide a set of methods to support visual analysis using GW statistics through which the effects of geography can be explored at multiple scales. [ABSTRACT FROM AUTHOR]

A wideband space-time channel model is defined, which captures the multiple dependencies and variability in multicell system-wide operating environments. The model provides a unified treatment of spatial and temporal parameters, giving their statistical description and dependencies across a large geographical area for three outdoor environments pertinent to third-generation cellular system simulations. Parameter values are drawn from a broad base of recently published wideband and multiple-antenna measurements. A methodology is given to generate fast-fading coefficients between a base station and a mobile user based on the summation of directional plane waves derived from the statistics of the space-time parameters. Extensions to the baseline channel model, such as polarized antennas, are given to provide a greater variety of spatial environments. Despite its comprehensive nature, the model's implementation complexity is reasonable so it can be used in simulating large-scale systems. Output statistics and capacities are used to illustrate the main characteristics of the model. [ABSTRACT FROM AUTHOR]

Modern digital relays use innovative algorithms to fulfill busbar protection requirements of fast operating times for all busbar faults, security for external faults with heavy current-transformer (CT) saturation, and minimum delay for evolving faults. This paper describes a reliable protection system that includes busbar protection and advanced zone selection; the protection system is suitable for the protection of multiple busbar arrangements. The protection system consists of several protection principles and measuring techniques using instantaneous and phasor quantities in a unique combination to achieve reliable busbar protection with minimum CT performance requirements. [ABSTRACT FROM PUBLISHER]

In this paper, the accuracy of location estimation of ad hoc deployed sensor nodes for a wireless sensor network in the presence of noisy environment and obstacle is discussed. Considering estimation accuracy, energy efficiency, and range independency, we propose a localization scheme using a mobile anchor node equipped with a directional antenna based on the geometry technique, called LSWD: Localization Scheme for Wireless Sensor Networks using Directional Antenna, this scheme make use of directional antenna concentrates energy on a particularly direction with high gain and narrow covering area. Without increasing hardware and computational complexity, sensor nodes estimate their positions using the minimum number of beacon information. Our localization scheme is verified by network simulation software. The result shows that the proposed localization algorithm has higher accuracy and energy efficiency than other localization schemes. 1. [ABSTRACT FROM AUTHOR]

A novel wavelet-based directional protection scheme is presented. Using the theory of wavelet singularity detection as a powerful signal processing tool, the initial arrival of the traveling wave and its sign can be identified reliably. Characteristics of the proposed directional protection algorithm are analyzed and the result of simulation studies are given. The wavelet based directional protection scheme solves several problems existing in current protective relays and is suitable for use as an ultra-high-speed UHV/EHV transmission line protective relay. [ABSTRACT FROM PUBLISHER]