In this paper, a new method for optimum coordination of overcurrent relays is proposed. The proposed based on only constraints. Minimization inherently included by setting the time dials to minimum and increasing their values gradually. Configuration changes network are taken into account. does not need any initial solution. It can consider both linear nonlinear relay characteristics models. optimal settings 8-Bus England Norweb networks obtained comparison between existing methods made.

We attempt a comprehensive review of all published research in nondestructive evaluation (NDE) performed with the superconducting quantum interference device (SQUID) magnetometer since first work was reported mid-1980s. The SQUID is most sensitive detector magnetic flux known. energy sensitivity may make it any kind. on SQUIDs for NDE based promise that and various other desirable properties developed instrumentation biomagnetism fields. instruments down to very low frequencies allows them...

An antenna theory (AT) approach in the frequency domain is presented to compute electromagnetic fields radiated by a lightning return stroke. The channel modeled as lossy-wire monopole (a wire with distributed resistance) energized current source at its base, and ground lossy half-space. method of moments used for solving governing electric field integral equation (EFIE) domain. resultant distribution along calculate different distances from channel. All components are evaluated using rapid...

Optimal Relays Coordination Efficient Method in Interconnected Power Systems In this paper an efficient method for optimal overcurrent relay coordination is proposed. the proposed using genetic algorithm, objective function (OF) developed to solve problem of miscoordination six pairs short circuit fault currents. The new OF improved be simple, and efficient. This technique takes into account changes network configuration. efficiency demonstrated by comparing results two different networks...

We review in this paper simplified analytical expressions derived by Wait using the concept of attenuation function for analysis propagation lightning radiated electromagnetic fields over a horizontally stratified ground. Considerations regarding use these formulations as well their domain applicability are given. For case, where upper ground layer has lower conductivity than layer, magnitude can take values greater unity. Time-domain waveforms vertical electric field along ground, obtained...

Traditionally, capacitor placement and conductor replacement have been considered as independent solutions for loss reduction in distribution networks. However, these two methods an inherent coupling relationship, especially at harmonic frequencies. This work presents a joint optimization algorithm both of overhead lines to minimize energy losses the presence harmonics throughout system, such that individual total distortion bus voltages are kept within acceptable levels. All actual...

A decentralized adaptive scheme is proposed in this article for protection coordination microgrids with topological and operational uncertainties. This performed two stages. In the first stage, a traditional fault deployed to clear fault. If isolated successfully, system returns regular fault-free state. not cleared due uncertainties system, second stage of initiated. based on federation structure, set agents around location negotiate reach best strategy upon occurrence single or multiple...

In the alternative current field measurement (ACFM) technique, nonzero value of liftoff distance for magnetic sensor acts as a low-pass filter on surface crack signals, causing errors in detection and sizing. We present blind deconvolution algorithm evaluation signal restoration. The employs available closed-form expressions distribution electromagnetic fields at metal vicinity crack. To examine accuracy algorithm, we use original restored signals sizing by wavelet network inversion method....

In this paper, a modification of the antenna theory (AT) model lightning return stroke to include inductive loading is presented. The distributed energy-storing elements are used in modified AT (designated as ATIL model, where IL stands for loading) control propagation speed upward traveling current wave without using an artificial, higher permittivity dielectric medium, done original model. variation along channel also considered proposed As resistive account attenuation with height....

AbstractThe development of a suitable scheme for protection DC microgrids is still major challenge. This due to the shortage practical experience in appropriate guidelines and standards related uncertainty network topology, absence natural current zero-crossing point systems, dependence fault shape magnitude on various factors. These factors include type converters used network, its location, impedance, system grounding. In this paper, these their impacts comprehensive plan have been...

A neural-network-based technique is described to determine the depth profile of a fatigue crack in metal from output signal an alternating current field measurement (ACFM) probe. The main feature this that it requires only measurements along opening. network uses multilayer perceptron structure for which training database established by systematically producing semi-elliptical multi-hump cracks with narrow openings and random lengths profiles. fast pseudo-analytic ACFM probe simulator also...

This paper presents a new method to find minimum number of Phasor Measurement Units (PMUs), determine the fault locations on transmission network lines in power system. Considering installation cost PMUs, it is important investigate placement scheme PMUs at minimal sense that location observability can be achieved over entire network. In this algorithm introduced an optimization problem for determining place and order accurate any systems. The accuracy suggested independent from type its...

A multiresolution (MR) (wavelet) basis is employed in the method of moments (MoMs) analysis to achieve an efficient evaluation electromagnetic wave coupling inside metallic enclosures with arbitrary-shape openings. In this method, electric field integral equation solved on surface enclosure discretized by triangular meshes. Using MR meshing, different scales problem such as small apertures and narrow slots are represented directly into functions constructed hierarchical sets...

The accuracy of approximate formulas for the evaluation lightning electromagnetic fields above and inside a lossy ground is investigated taking as reference full-wave numerical results obtained using parallel implementation finite-difference time-domain (FDTD) technique. return stroke channel modeled antenna theory model with fixed inductive loading which appropriately incorporated into FDTD algorithm. First, validity Cooray-Rubinstein (CR) formula above-ground horizontal electric field...

This paper proposes an efficient modeling technique for transient electromagnetic analysis of a rectangular metallic enclosure with multiple apertures, using the surface equivalent principle (SEP) and integral equations. The SEP is used to replace apertures by perfect electric conductor surfaces while introducing appropriate magnetic current densities on both sides apertures. As result, problem reduced two independent regions. first region outside which free-space Green's function aid image...

This paper presents a modeling technique to predict the output signal of an open-ended rectangular waveguide probe when scanning arbitrary-shape crack in lossy conductor with finite conductivity. The loss specimen is taken into account by using surface impedance at surface. discretizes shape and applies generalized scattering matrix obtain signal. To validate model proposed this paper, results method are compared measurement those obtained finite-element code. used appropriate inversion...

In this paper, a new technique is developed to evaluate efficiently the Sommerfeld integrals arising from problem of current element radiating over lossy half-space.The annihilation asymptote and branch-point singular behavior spectral Green's function used in technique.The contributions subtracted asymptotic singularity terms are calculated analytically.The results remaining integral that very smooth can be adaptively by using Gaussian quadratures extrapolation methods accelerate...

Power systems are usually subjected to some changes in connections during operation, which leads varied short-circuit levels different parts of them and Directional Overcurrent Relays (DOCRs) may be miscoordination by changing short circuit levels. Therefore, all network topologies should considered for coordination among overcurrent relays a power system. Reduction operating time is highly important protection This paper uses the with time-current-voltage curve respect topologies. improves...