Power System

The Public Perception of Power Blackouts

by Helen Brayley

Co-authored with Miles Redfern and Z. Bo

A Matriz do Poder. Uma visão analítica da Globalização e da Anti-Globalização no Mundo Contemporâneo

by Sandra Rodrigues Balão

Published by MGI Ed.

Power Quality enhancement using Dynamic Voltage Restorer

by Krishna Prasad

The ultimate objective of the power system is to
optimize the production while minimizing the production costmore The ultimate objective of the power system is to
optimize the production while minimizing the production cost
and thereby achieving maximized profits while ensuring
continuous production throughout the period. This paper
presents a new control technique to detect and compensate for
the voltage sag& swell and the simulation was checked in the
MATLAB/SIMULINK software and has shown reliable
results.
Index Terms— DVR, voltage dips, swells, interruption, power
quality, VSC.

L'espace public à travers le prisme du pouvoir: quelques éléments de réflexion à partir d'un cas tripolitain (Liban)

by Bruno Dewailly

Induction Generator Model Parameter Estimation using Improved Particle Swarm Optimization and On-Line Response to a Change in Frequency

by Francisco Gonzalez-Longatt

P. Regulski, F. González-Longatt, P. Wall, and V. Terzija., "Induction Generator Model Parameter Estimation using Improved Particle Swarm Optimization and On-Line Response to a Change in Frequency,"
in 2011 IEEE Power & Energy Society General Meeting, Detroit, Michigan, USA, 2011.

An induction generator (IG) is preferred to a synchronous generator in many renewable energy applications. In order to... more An induction generator (IG) is preferred to a synchronous generator in many renewable energy applications. In order to achieve proper control of an induction generator it is important to have accurate knowledge of its model parameters. In this paper, an Improved Particle Swarm Optimization (IPSO) approach is used to estimate the model parameters of an IG. The IPSO is executed based on the response of the active and reactive power flows associated with the IG to a change in the frequency of the external system, which the IG is connected to. This change in frequency is applied when the IG is operating in steady state, to represent the scenario where the IG parameters must be estimated on-line, and during a large disturbance to the system equilibrium. This approach is in contrast to others in the literature that estimate the parameters of an induction machine based on its start-up behavior, or the results of mechanical tests. Therefore, this approach should offer benefits when the parameters of the IG being modeled may vary over time and need to be estimated on-line.

Induction Generator Model Parameter Estimation using Improved Particle Swarm Optimization and On-Line Response to a Change in Frequency

by Francisco Gonzalez-Longatt

P. Regulski, F. González-Longatt, P. Wall, and V. Terzija., "Induction Generator Model Parameter Estimation using Improved Particle Swarm Optimization and On-Line Response to a Change in Frequency,"
in 2011 IEEE Power & Energy Society General Meeting, Detroit, Michigan, USA, 2011.

An induction generator (IG) is preferred to a synchronous generator in many renewable energy applications. In order to... more An induction generator (IG) is preferred to a synchronous generator in many renewable energy applications. In order to achieve proper control of an induction generator it is important to have accurate knowledge of its model parameters. In this paper, an Improved Particle Swarm Optimization (IPSO) approach is used to estimate the model parameters of an IG. The IPSO is executed based on the response of the active and reactive power flows associated with the IG to a change in the frequency of the external system, which the IG is connected to. This change in frequency is applied when the IG is operating in steady state, to represent the scenario where the IG parameters must be estimated on-line, and during a large disturbance to the system equilibrium. This approach is in contrast to others in the literature that estimate the parameters of an induction machine based on its start-up behavior, or the results of mechanical tests. Therefore, this approach should offer benefits when the parameters of the IG being modeled may vary over time and need to be estimated on-line.

Hiroshima

by Glendy Aponte

When looking back on the bombing of Hiroshima, it has been shown that history and politics can come together to... more When looking back on the bombing of Hiroshima, it has been shown that history and politics can come together to influence the opinions of a society.

Écrire l'histoire d'un conflit entre élites dans l'Islande médiévale. Remarques sur la Svínfellinga saga

by gregory cattaneo

Published in the Cahiers de l'Institut de Recherche Stratégique de l'Ecole militaire (IRSEM), 2012.

Paper coming from the talk: “Ecrire l’histoire d’une rivalité entre élites: quelques remarques sur Oddaverja Þáttr”, International conference, “the historical value of the sagas”, University of Caen Basse Normandie, France, february 2012

Travail présenté à Caen, le 17 février 2012, dans une conférence portant sur la valeur historique des sagas. Travail présenté à Caen, le 17 février 2012, dans une conférence portant sur la valeur historique des sagas.

Hybrid emergency voltage control in power systems

by Tobias Geyer

Reducing Variation in Solar Energy Supply Through Frequency Domain Analysis

by Shrisha Rao

Co-authored with Chandrashekhar Lavania and Eswaran Subrahmanian.
IEEE Systems Journal, vol. 6 (2), June 2012, pp. 196--204. doi:10.1109/JSYST.2011.2162796.

Solar irradiation tends to vary greatly throughout the day. The difference is very large especially between the early... more Solar irradiation tends to vary greatly throughout the day. The difference is very large especially between the early hours of sunshine, and during the peak hours of the day. Yet, it is desirable to supply a nearly constant amount of power to loads or power grids for high reliability. Hence, we propose a technique aimed at reducing the variation in solar power generation. Solar irradiation data is considered as a time-series data and the approach involves conversion of this data to the frequency domain through Fourier analysis. A more balanced supply by a set of plants is devised by interconnecting the plants, which also requires finding the optimum number of plants to connect using the above analysis. The effectiveness of the procedure is demonstrated by applying a suitable supply prediction algorithm over the individual plants and the effective data for the plants, using real data from Nevada, Texas, and California.

Liberalizmden Neoliberalizme Güç Olgusu ve Sistemik Bağımlılık

by Uluslararası İlişkiler

Yücel BOZDAĞLIOĞLU-Çınar ÖZEN, "Liberalizmden Neoliberalizme Güç Olgusu ve Sistemik Bağımlılık", Uluslararası İlişkiler, Cilt 1, Sayı 4 (Kış ), 2004.

Bu çalışmanın ana inceleme konusu sistemik güç olgusudur. Liberal uluslararasıcılık ve neoliberalizm çerçevesinde... more Bu çalışmanın ana inceleme konusu sistemik güç olgusudur. Liberal uluslararasıcılık ve neoliberalizm çerçevesinde teorik olarak tanımlanmaya çalışılan güç kavramı, realizmin tanımladığı güç kavramıyla da karşılaştırmalı olarak incelenmektedir. Bu çerçevede liberal/neoliberal ile realist yaklaşımların güç tanımları arasında büyük bir fark olmadığı, her iki okulun da ulaşılması hedeflenen sonuçlar itibariyle benzeştiği sonucuna ulaşılmıştır. Realizm uluslararası ilişkilerde askeri gücün önemine vurgu yaparken, liberalizm/neoliberalizm ekonomik ilişkilerden kaynaklanan gücün önemine işaret etmiştir. Bu çerçevede ortaya konan sistemik güç, bir devletin diğer devletlerin davranışlarını doğrudan etkileyebilme kapasitesi değil ekonomik ve siyasal sistemin yapısının değiştirilebilmesi sayesinde elde edilen güç olarak tanımlanmıştır. Bu anlamda sistemik güç uluslararası ilişkilerde hegemonyanın oluşturulması ve sürdürülebilmesi için büyük önem kazanmıştır.

Review: Risa Brooks and Elizabeth Stanley (eds.), 2007. Creating Military Power: The Sources of Military Effectiveness. Stanford: Stanford University Press.

by Jonas Hagmann

Published in: H-Net, 2008

Comprising a conceptual framework, seven substantive chapters, a critical individual synthesis reflecting on the book... more Comprising a conceptual framework, seven substantive chapters, a critical individual synthesis reflecting on the book itself and a summary conclusion, this edited book provides a set of constructive conceptual and empirical contributions to international relations, political science, and military studies. Its key argument is that national military power is too often simplistically equated with states' material and human resources, ignoring the divergent effectiveness with which states make actual use of them. In sum, and certain conceptual challenges notwithstanding, Creating Military Power provides a rather well-accomplished and differentiated analysis of the manifold sources of military power, making it a welcomed contribution to the ongoing reconceptualization of military power. With latent US ethnocentrism in some of its chapters, it is also recommendable to all those interested in the state of current US scholarship on international security studies

How to Efficiently Incorporate FACTS Devices in Optimal Active Power Flow Model

by Anibal Azevedo

A.T. Azevedo, A.R.L. Oliveira, M.J. Rider, S. Soares, , Journal of Industrial and Management Optimization, ISSN 1547-5816, Volume 6, Number 2, pp. 315-331, 2010

This paper presents for the first time how to easily incorporate facts devices in an optimal active power flow model... more This paper presents for the first time how to easily incorporate facts devices in an optimal active power flow model such that an efficient interior-point method may be applied. The optimal active power flow model is based on a network flow approach instead of the traditional nodal formulation that allows the use of an efficiently predictor-corrector interior point method speed up by sparsity exploitation. The mathematical equivalence between the network flow and the nodal models is addressed, as well as the computational advantages of the former considering the solution by interior point methods. The adequacy of the network flow model for representing facts devices is presented and illustrated on a small 5-bus system. The model was implemented using Matlab and its performance was evaluated with the 3,397-bus and 4,075- branch Brazilian power system which show the robustness and efficiency of the formulation proposed. The numerical results also indicate an efficient tool for optimal active power flow that is suitable for incorporating facts devices.

Security constrained optimal active power flow via network model and interior point method

by Anibal Azevedo

AZEVEDO, Anibal T. de; CASTRO, Carlos A.; OLIVEIRA, Aurelio R.L.  and  SOARES, Secundino. Security constrained optimal active power flow via network model and interior point method. Sba Controle & Automação [online]. 2009, vol.20, n.2, pp. 206-216. ISSN 0103-1759.  doi: 10.1590/S0103-17592009000200008.

This paper presents a new formulation for the security constrained optimal active power flow problem which enables the... more This paper presents a new formulation for the security constrained optimal active power flow problem which enables the representation of three basic constraints: branch outage, generator outage and multiple equipment congestion. It consists of a network model with additional linear equality and inequality constraints and quadratic separable objective function, which is efficiently solved by a predictor-corrector interior point method. Sparsity techniques are used to exploit the matricial structure of the problem.Case studies with a 3,535-bus and a 4,238-branch Brazilian power system are presented and discussed, to demonstrate that the proposed model can be efficiently solved by an interior point method, providing security constrained solutions in a reasonable time.

Interior point method for long-term generation scheduling of large-scale hydrothermal systems

by Anibal Azevedo

A.T. Azevedo, A.R.L. Oliveira, S. Soares, Annals of Operations Research, ISSN 0254-5330, DOI 10.1007/s10479-008-0389-z, Friday, July, 04, 2008. Published on-line.

This paper presents an interior point method for the long-term generation scheduling of large-scale hydrothermal... more This paper presents an interior point method for the long-term generation scheduling of large-scale hydrothermal systems. The problem is formulated as a nonlinear programming one due to the nonlinear representation of hydropower production and thermal fuel cost functions. Sparsity exploitation techniques and an heuristic procedure for computing the interior point method search directions have been developed. Numerical tests in case studies with systems of different dimensions and inflow scenarios have been carried out in order to evaluate the proposed method. Three systems were tested, with the largest being the Brazilian hydropower system with 74 hydro plants distributed in several cascades. Results show that the proposed method is an efficient and robust tool for solving the long-term generation scheduling problem.

A nonlinear model for the long-term hydro-thermal generation scheduling problem over multiple areas with transmission constraints

by Anibal Azevedo

Co-Authored with Leonardo S. A. Martins and Secundino Soares. Published in Power Systems Conference and Exposition - PSCE, March 15-18, Seattle, USA,2009

This paper presents a nonlinear model with individual
representation of plants for the centralized long-term... more This paper presents a nonlinear model with individual
representation of plants for the centralized long-term hydrothermal
scheduling problem over multiple areas. In addition
to common aspects of long-term scheduling, this model takes
transmission constraints into account. The ability to optimize
hydropower exchange among multiple areas is important because
it enables further minimization of complementary thermal
generation costs. Also, by considering transmission constraints
for long-term scheduling, a more precise coupling with shorter
horizon schedules can be expected. This is an important characteristic
from both operational and economic viewpoints. The
proposed model is solved by a sequential quadratic programming
approach in the form of a prototype system for different case
studies. An analysis of the benefits provided by the model is also
presented.

Wake effect in wind farm performance: Steady-state and dynamic behavior

by Francisco Gonzalez-Longatt

F. González-Longatt, P. Wall, and V. Terzija, "Wake effect in wind farm performance: Steady-state and dynamic behavior," Renewable Energy, vol. V, p. PP, 2011.

The aim of this paper is to evaluate the impact of the wake effect on both the steady-state operation and dynamic... more The aim of this paper is to evaluate the impact of the wake effect on both the steady-state operation and dynamic performance of a wind farm and provide conclusions that can be used as thumb rules in generic assessments where the full details of the wind farms are unknown. A simplified explicit model of the wake effect is presented, which includes: the cumulative impact of multiple shadowing, the effects of wind direction and the wind speed time delay. The model is implemented in MATLAB® and then integrated into a power system simulation package to describe the wake effect and its impact on a wind farm, particularly in terms of the wake coefficient and overall active power losses. Results for two wind farm layouts are presented to illustrate the importance of wind turbine spacing and the directionality of wind speeds when assessing the wake effect during steady-state operation and dynamic behavior.

Kaleidoscope of roles: valuing the agencies of the audience, client and the designer

by Yoko Akama

Presented at Include 2007 conference, Designing with people, Royal College of Art, London, UK, April 2-4, 2007.

This paper broadens the discussion on the inclusiveness of design process. It discusses an inclusive approach to... more This paper broadens the discussion on the inclusiveness of design process. It discusses an inclusive approach to communication design projects that values the agencies of various stakeholders involved. In particular, this paper explores the importance of the designers’ human agency to enable a human-centred approach in the practice of communication design. The paper draws on data drawn from design-led investigations and interviews with design practitioners. These were undertaken as part of the author’s practice-led doctorate research, which is situated in the field of communication design.

What roles do people play during the design process? How does this affect the design outcome? The paper argues that the multiplicity of perspectives is vital to the design process in creating engaging and meaningful outcomes for all concerned. A dialogic interaction that occurs between various people in the project facilitates multiplicity of perspectives. The paper concludes with a proposition for communication design to embrace the notion that designing is an interpersonal, complex and layered process that includes the multiple roles that people have.

Induction Generator Model Parameter Estimation using Improved Particle Swarm Optimization and On-Line Response to a Change in Frequency

by Francisco Gonzalez-Longatt

P. Regulski, F. González-Longatt, P. Wall, and V. Terzija., "Induction Generator Model Parameter Estimation using Improved Particle Swarm Optimization and On-Line Response to a Change in Frequency,"
in 2011 IEEE Power & Energy Society General Meeting, Detroit, Michigan, USA, 2011.

An induction generator (IG) is preferred to a synchronous generator in many renewable energy applications. In order to... more An induction generator (IG) is preferred to a synchronous generator in many renewable energy applications. In order to achieve proper control of an induction generator it is important to have accurate knowledge of its model parameters. In this paper, an Improved Particle Swarm Optimization (IPSO) approach is used to estimate the model parameters of an IG. The IPSO is executed based on the response of the active and reactive power flows associated with the IG to a change in the frequency of the external system, which the IG is connected to. This change in frequency is applied when the IG is operating in steady state, to represent the scenario where the IG parameters must be estimated on-line, and during a large disturbance to the system equilibrium. This approach is in contrast to others in the literature that estimate the parameters of an induction machine based on its start-up behavior, or the results of mechanical tests. Therefore, this approach should offer benefits when the parameters of the IG being modeled may vary over time and need to be estimated on-line.

Modelo Dinámico para Celda de Combustible: Aplicación en Generación Distribuida

by Francisco Gonzalez-Longatt