Showing 37–48 of 203 results
Application of Duffing Oscillators for Passive Islanding Detection of Inverter-Based Distributed Generation Units
Regarding the safetyرایگان!
Regarding the safety and reliable operation of modern distributed generation (DG) systems, an expert diagnosis apparatus is required to distinguish between different events. One of the crucial requirements in DG safe operation is the “islanding detection.” In this paper, a new passive islanding detection method, based on the application of the Duffing oscillators, is suggested for the first time and tested under different network conditions. The method is designed to detect the changes on point of common coupling frequency by identifying the transformation of the Duffing oscillator from “chaotic state” to “great periodic state” and vice-versa. The simulations results, carried out by MATLAB/Simulink, are used to validate the performance of the proposed method. It is shown that the proposed method has excellent accuracy within a minimum detection time, even with the presence of high noise to signal ratios.
Artificial immune system for dynamic economic dispatch
Dynamic economic disرایگان!
Dynamic economic dispatch determines the optimal scheduling of online generator outputs with predicted load demands over a certain period of time taking into consideration the ramp rate limits of the generators. This paper proposes artificial immune system based on the clonal selection principle for solving dynamic economic dispatch problem. This approach implements adaptive cloning, hyper-mutation, aging operator and tournament selection. Numerical results of a ten-unit system with nonsmooth fuel cost function have been presented to validate the performance of the proposed algorithm. The results obtained from the proposed algorithm are compared with those obtained from particle swarm optimization and evolutionary programming. From numerical results, it is found that the proposed artificial immune system based approach is able to provide better solution than particle swarm optimization and evolutionary programming in terms of minimum cost and computation time.
Assessment of Light Flicker Mitigation using Shunt Compensators
The main objectiveofرایگان!
The main objectiveof this paper is to compare the relative effectiveness of shunt compensators in mitigating light flicker caused by arc furnace. A test system comprising an arc furnace model built in PSCADEMTDC is simulated with and without the Static Var Compensator (SVC) and Static Synchronous Compensator (STATCOM). Compensation characteristics of the devices are measured in terms of fficker severity indices (et) using IEC compliant flickermeter model developed in PSCAD/EMTDC. The simulation results demonstrate that the STATCOM has superior flicker reduction capacity than the SVC due to its inherently faster response .
Asymmetric gain-saturated spectrum in fiber optical parametric amplifiers
We demonstrate experرایگان!
We demonstrate experimentally and numerically an unexpected spectral asymmetry in the saturated-gain spectrum of single-pump fiber optical parametric amplifiers. The interaction between higher-order fourwave mixing products and dispersive waves radiated as an effect of thirdorder dispersion influences the energy transfer to the signal, depending on its detuning with respect to the pump, and breaks the symmetry of the gain expected from phase-matching considerations in unsaturated amplifiers. The asymmetry feature of the saturated spectrum is shown to particularly depend on the dispersion characteristics of the amplifier and shows local maxima for specific dispersion values .
Autism Spectrum Disorders in Adults
The term autism wasرایگان!
The term autism was first introduced in 1908. The famous Swiss psychiatrist Eugen Bleuler used the term autism to describe the very aloof and withdrawn condition of some patients with what he called schizophrenia. Leo Kanner (1943), when describing eleven children with “an autistic disturbance of affective contact”, clearly had Bleuler’s thoughts in mind. Likewise Hans Asperger (1944) called the atypical boys in his study “autistic psychopaths”, hereby also alluding to some resemblance with schizophrenia. Despite the fact that “autistic aloofness” does not by far cover the complexity of the pervasive developmental disorder described nowadays as “autism spectrum disorder”, the term has become the common way to describe the large range of individuals with a syndrome characterized by impairments of the development of social and communicative reciprocity and a rigid and restricted repertoire of interests and behaviours. In this chapter a historical overview of the development of a concept in psychopathology will be presented. It may be interesting to note, before entering into the matter, that Bleuler believed that there was a continuum between psychiatric disorders and normality. This is very much in line with the current concept of a broad autism spectrum ranging from severe cases to well-adapted individuals with autistic features bordering what Simon Baron-Cohen would call an autistic condition including 5 % of the population.
Automated Demand Response From Home Energy Management System Under Dynamic Pricing and Power and Comfort Constraints
This paper presentsرایگان!
This paper presents a comprehensive and general optimization-based home energy management controller, incorporating several classes of domestic appliances includingdeferrable, curtailable, thermal, and critical ones. The operations of the appliances are controlled in response to dynamic price signals to reduce the consumer’s electricity bill whilst minimizing the daily volume of curtailed energy, and therefore considering the user’s comfort level. To avoid shifting a large portion of consumer demand toward the least price intervals, which could create network issues due to loss of diversity, higher prices are applied when the consumer’s demand goes beyond a prescribed power threshold. The arising mixed integer nonlinear optimization problem is solved in an iterative manner rolling throughout the day to follow the changes in the anticipated price signals and the variations in the controller inputs while information is updated. The results from different realistic case studies show the effectiveness of the proposed controller in minimizing the household’s daily electricity bill while preserving comfort level, as well as preventing creation of new least-price peaks.
Auxiliary-Carrier Load-Shift Keying for Reverse Data Telemetry from Biomedical Implants
This paper introduceرایگان!
This paper introduces a new approach for data telemetry from biomedical implantable devices to the external world (also known as reverse data telemetry). In the proposed approach, while power (and perhaps data) is transferred to the implant using a main carrier, a second carrier is also sent to the implant through the same link. The second carrier, which is of higher frequency and smaller amplitude, is envisioned for reverse data telemetry by load-shift keying. In this work, the wireless link is realized with two resonant frequencies using closely-coupled printed spiral coils and LC matching networks. The main and auxiliary carrier frequencies are 1MHz and 10MHz with 5V and 1V peak amplitudes, respectively. While the link is capable of continuously supplying unregulated power of up to 80mW at 4V(peak) to a 100-Ω resistive load, data telemetry at a rate of 100 kbps is successfully tested in the reverse direction.
Battery Energy Storage Station (BESS)-Based Smoothing Control of Photovoltaic (PV) and Wind Power Generation Fluctuations
The battery energy sرایگان!
The battery energy storage station (BESS) is the current and typical means of smoothing wind- or solar- power generation fluctuations. Such BESS-based hybrid power systems require a suitable control strategy that can effectively regulate power output levels and battery state of charge (SOC). This paper presents the results of a wind/photovoltaic (PV)/BESS hybrid power system simulation analysis undertaken to improve the smoothing performance of wind/PV/BESS hybrid power generation and the effectiveness of battery SOC control. A smoothing control method for reducing wind/PV hybrid output power fluctuations and regulating battery SOC under the typical conditions is proposed. A novel real-time BESS-based power allocation method also is proposed. The effectiveness of these methods was verified using MATLAB/SIMULINK software.
Benefits of Power Electronic Interfaces for Distributed Energy Systems
With the increasingرایگان!
With the increasing use of distributed energy (DE) systems in industry and its technological advancement, it is becoming more important to understand the integration of these systems with the electric power systems. New markets and benefits for DE applications include the ability to provide ancillary services, improve energy efficiency, enhance power system reliability, and allow customer choice. Advanced power electronic (PE) interfaces will allow DE systems to provide increased functionality through improved power quality and voltage/volt–ampere reactive (VAR) support, increase electrical system compatibility by reducing the fault contributions, and flexibility in operations with various other DE sources, while reducing overall interconnection costs. This paper will examine the system integration issues associated with DE systems and show the benefits of using PE interfaces for such applications.
Bias Estimation for Evaluation of ATC surveillance systems
This paper describesرایگان!
This paper describes an off-line bias estimation and correction system for Air Traffic Control related sensors, used in a newly developed Eurocontrol tool for the assessment of ATC surveillance systems. Current bias estimation algorithms are mainly focused in radar sensors, but the installation of new sensors (especially Automatic Dependent Surveillance-Broadcast and Wide Area Multilateration) demands the extension of hose procedures. In this paper bias estimation architecture is designed, based on error models for all those sensors. The error models described rely on the physics of the measurement process. The results of these bias estimation methods will be exemplified with simulated data.
Bistability and Switching Properties of Semiconductor Ring Lasers With External Optical Injection
We investigate bothرایگان!
We investigate both analytically and numerically the switching, locking and stability properties of a bistable semiconductor ring laser subject to an external optical injection. Minimum optical power required for the injected signal at certain frequency to switch the lasing direction of a bistable semiconductor ring laser from its initially lasing direction to initially nonlasing direction is determined. Locking to the injected signal and stability of the switched laser are investigated to give an area of reliable switching operation. Correspondingly, numerical simulation has been carried out to find successful switching and stable locking region with variable injection power and frequency, and is compared with the analytical results. The region obtained from simulation coincides well with the intersection of switching, locking and stable locking regions. The relation between switching speed and parameters of injected source is also studied numerically.
Capacity withholding equilibrium in wholesale electricity markets
This paper is a quanرایگان!
This paper is a quantitative study of the capacity withholding incentives in the deregulated wholesale electricity markets and resulting price spikes. For the analysis we used an N-player Nash equilibrium model based on marginal cost functions of the generating firms assuming completely inelastic industry demand and complete information. The current results show that in the case of continuous marginal costs the withholding incentive always exists and the total withholding increases with the increase of the curvature of marginal cost functions and the extent of heterogeneity of the generating firms. The discrete form of real marginal cost functions imposes certain restrictions on the withholding. The analysis shows that there exists a threshold level of market demand below which no withholding occurs and above which the withholding becomes beneficial. The curvature and heterogeneity of marginal cost functions also affect the level of this threshold. The model is applied to the power generation in California ISO area.