2,974 results
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2. Worker Contact with Electricity: The Characteristics of a Workplace Electrical Fatality: Copyright Material IEEE Paper No. ESW2021-06
- Author
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Daniel Majano and Brett Brenner
- Subjects
Engineering ,Construction industry ,business.industry ,Occupational injury ,medicine ,Operations management ,Electricity ,business ,Private sector ,Energy source ,medicine.disease ,Occupational safety and health - Abstract
According to the U.S. Bureau of Labor Statistics, since the introduction of the Occupational Injury and Illness Classification System 2.01 in 2011, half of all private industry workplace electrical fatalities occurred within the construction industry. Between 2011 and 2019, the Occupational Safety and Health Administration (OSHA) recorded that 378 cases of electrical fatalities occurred during construction projects. OSHA reports show that the greatest number of electrically related fatalities occurred in alterations or rehabilitations and in new projects or addition builds. Many of these construction projects were for single-family, duplex, or commercial building projects. In examining incidents where contacted voltage was recorded, 57% of fatalities occurred when a worker contacted an energy source of over 1,000 volts. Contact with energy sources of 480 volts and 7,200 volts accounted for the greatest number of fatalities. Gaining a better understanding of the jobs being completed and the source of energy contacted can help identify the behaviors and actions that need to be addressed to lower the number of electrical fatalities in the workplace.
- Published
- 2021
3. Power Quality Durvey on Italian Industrial Customers: Paper Industries
- Author
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A. Prudenzi, S. Mascitelli, and Maria Carmen Falvo
- Subjects
Engineering ,Textile industry ,business.industry ,Process (engineering) ,Environmental economics ,Customers susceptibility ,Paper industry ,Power quality ,Manufacturing engineering ,Electric power system ,Order (business) ,Secondary sector of the economy ,Production (economics) ,Electricity ,business - Abstract
The paper deals with power quality (PQ) issues in the specific industrial sector of paper fabrication. In this sector a wide research activity has been performed at customers level in order to identify main susceptibilities of the industrial process and to determine costs associated to PQ events. To this aim data, made available both from production process logs and from electricity distributor protection system interruption recordings, have been used. Finally, some real figures of possible costs due to PQ problems have been identified and discussed in details.
- Published
- 2008
4. Energy Conservation and CO>inf<2>/inf<Reduction by Conversion of Paper Document to Electronic Document using High Speed Color Multifunction Device with Document Flow Software
- Author
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K. Masuda and A. Inoue
- Subjects
Reduction (complexity) ,Energy conservation ,Engineering ,Service (systems architecture) ,Software ,Paper document ,Flow (mathematics) ,business.industry ,Embedded system ,Electronic document ,Electricity ,business ,Computer hardware - Abstract
Electricity and paper consumptions were estimated quantitatively for the cases where paper documents can be easily converted to electronic ones using combination of Fuji Xerox's multifunctional device of DocuCentre Color 450 and Fuji Xerox's software of DocuCentre Flow Service. For the typical case reduction of electricity and paper consumption as high as 15% and 0. 79 t was shown to be attained
- Published
- 2006
5. An innovative pricing option for electricity as used by the pulp and paper industry
- Author
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P.W. Magnabosco and M.T. O'Sheasy
- Subjects
Marginal cost ,Engineering ,Cogeneration ,Load management ,business.industry ,Open market operation ,Mill ,Electricity ,Activity-based costing ,business ,Pulp and paper industry ,Energy source - Abstract
The pulp and paper industry relies heavily on electricity as an energy source. Although a major share of the pulp and paper industry's electrical needs are met by cogeneration, a substantial quantity of utility-generated electricity is purchased. The cost of purchased electricity can have a significant "bottom line" impact on mill production costs. Some utilities now have a new and innovative pricing methodology that provides cost benefits to their pulp and paper customers while also allowing utilities to achieve their own load management goals. This pricing concept is based on a utility's marginal cost structure, and is generally known as real time pricing or RTP. This paper provides an explanation of the RTP concept for purchased electricity. It compares and contrasts RTP pricing concepts to more traditional electric rates and describes the potential benefits to the utility's load management strategy. An actual pulp and paper mill's perspectives with RTP are presented from the standpoint of mill operations and the economic benefit of this innovative rate structure. Many mills will have the option to obtain a lower cost supply of purchased electricity in accordance with their process requirements while using operational capabilities in conjunction with the utilities' load management programs. Through the development and use of RTP programs, electric utilities can achieve load management objectives, better use generation resources, and be prepared to compete in an emerging open market place.
- Published
- 2002
6. Electrical energy usage in the pulp and paper industry
- Author
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R.D. Giese, J. Holmquist, and K.R. Amarnath
- Subjects
Engineering ,Electrical load ,Waste management ,business.industry ,Electric potential energy ,Energy resources ,Energy consumption ,Pulp and paper industry ,chemistry.chemical_compound ,chemistry ,Thermal ,Petroleum ,Electricity ,Energy source ,business - Abstract
The authors examine the electrical energy usage in the pulp and paper industry for the continental United States. It is noted that the broad picture of energy required and fuel sources used gives a clear indication of a movement away from oil as an energy source. Internally generated fuel sources of spent liquor and hogged fuel have increased. The steam generated from boilers has increased internally generated electricity. It is pointed out that technologies such as high-yield pulping and impulse drying require less chemicals and reduced thermal requirements. The advanced thermal analysis technique of pinch technology focuses on optimum use of thermal requirements. It is concluded that all of these technologies point the way to more efficient thermal usage and increased demand for electricity. >
- Published
- 2002
7. Social impact of power semiconductor devices (Invited Paper)
- Author
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Bantval Jayant Baliga
- Subjects
Consumption (economics) ,Engineering ,business.industry ,Electrical engineering ,Automotive industry ,Insulated-gate bipolar transistor ,Semiconductor device ,Automotive engineering ,law.invention ,Renewable energy ,Ignition system ,law ,Electricity ,Gasoline ,business - Abstract
Silicon IGBTs are now used in all the major sectors of our economy including transportation, consumer, lighting, industrial, medical, and renewable energy generation. The improved efficiency derived from IGBT-based automotive electronic ignition systems, adjustable speed motor drives, and compact fluorescent lamps has reduced gasoline consumption by over 1 Trillion gallons and electricity consumption by over 50,000 Terra-Watt-Hours. The social impact includes consumer cost savings of more than $15 Trillion and carbon dioxide emission reduction by over 75 Trillion pounds.
- Published
- 2014
8. Investigation of the effects of fast transients on a transformer's paper insulation
- Author
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Johan J. Smit, T.L. Koltunowicz, D. Djairam, and G. Bajracharya
- Subjects
Engineering ,business.industry ,Electric breakdown ,Life time ,Accelerated aging ,law.invention ,Electricity generation ,law ,Electronic engineering ,Waveform ,Power grid ,Electricity ,business ,Transformer - Abstract
Identifying future trends in the power grid is vital in the extension of the life of its already aging components. Fast transients are the new factors that need to be taken into consideration as their high repetitive frequencies and fast rise times accelerate the aging of the paper insulation in devices such as transformers. As will be outlined below, an aging set-up has been proposed to study these effects on paper insulation in relation to the time to failure. The aging waveform generation is discussed together with the steps taken to assess the influence of the fast transients. Initial test results will be presented on paper samples used in a transmission transformer showing that the transient waveform has a factor of 2 in shortening the life time of the cellulose.
- Published
- 2010
9. Increase of paper mill energy efficiency by optimization energy supply system industry
- Author
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Horia Necula, Adrian Badea, Roxana Grigore, Aneta Hazi, and Gh. Hazi
- Subjects
Engineering ,Cogeneration ,Waste management ,business.industry ,Production (economics) ,Energy supply ,Energy consumption ,Electricity ,AC power ,business ,Process engineering ,Energy accounting ,Efficient energy use - Abstract
Due to the high energy consumption in a paper mill, energy cost is an important part of the overall production cost of paper. Papermaking is a continuous process. Ensuring a continuous energy supply for this process would avoid production losses and supplementary energy consumption for restarting the installations. In this paper we develop an optimization model of the energy supply system from the perspectives of reliability and energy loss. Subsequently we use this model to analyze the energy supply system in order to find some solutions for increasing the energy efficiency and for reducing the cost of accidental outages.
- Published
- 2009
10. Energy and waste saving measures for the paper and wood products industry
- Author
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S. Dunning and T. Ward
- Subjects
Energy conservation ,Engineering ,Documentation ,Waste management ,Wood processing ,Natural gas ,business.industry ,Source reduction ,Energy (esotericism) ,Sample (statistics) ,Electricity ,Environmental economics ,business - Abstract
The forest products industry is one of the largest energy consuming sectors of American industry. As such, it is also one of the eight "Industries of the Future" targeted by the US Department of Energy's Office of Industrial Technologies (DOE-OIT). The Department of Energy is currently spending millions of dollars in cooperative research with forest products firms to develop new energy-efficient technology to improve the competitiveness of US Companies. In addition, DOE has developed technology transfer programs to provide assist in the dissemination of new and existing technology to these firms. These assessments contain recommendations for reducing energy use in all forms (oil, natural gas, electricity, etc.) and cover source reduction of all raw and finished products (water, sewer, paper, packaging, etc.) This paper discusses the various recommendations made during these assessments. It includes the most common energy conservation opportunities and waste minimization opportunities. Sample calculations are provided as well as documentation of resources for additional information.
- Published
- 2002
11. Integration of plug in hybrid electric vehicles and electric vehicles - experience from Sweden
- Author
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Sonja Lundmark, Lina Bertling, David Steen, and Ola Carlson
- Subjects
Engineering ,business.product_category ,business.industry ,Short paper ,Electrical engineering ,computer.software_genre ,Grid ,Automotive engineering ,Wide area ,Work (electrical) ,Harmonics ,Electric vehicle ,Plug-in ,Electricity ,business ,computer - Abstract
Integration of plug in hybrid electric vehicles and electric vehicles (PHEVs and EVs) includes a wide area of topics like grid effects, different charging concepts, charger designs, harmonics from the charger etc. This short paper gives an introduction to ongoing work within this field in Sweden, and shows on research work within the topic at Chalmers University of Technology.
- Published
- 2010
12. Unit Commitment With Probabilistic Spinning Reserve and Interruptible Load Considerations.
- Author
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Aminifar, Farrokh, Fotuhi-Firuzabad, Mahmud, and Shahidehpour, Mohammad
- Subjects
PROBABILITY theory ,MATHEMATICS ,ELECTRIC power systems ,ELECTRICITY ,POWER resources ,ENERGY industries ,INTEGER programming ,MATHEMATICAL programming ,ENGINEERING - Abstract
This paper demonstrates how a probabilistic criterion could be explicitly integrated in the unit commitment (UC) formulation. Both spinning reserve and interruptible load are taken into account as the operating reserve facilities. Incorporating the interruption notice time of interruptible load involves some complexities in the evaluation procedure and problem formulation which is considered in this paper. The expected energy not supplied (EENS) is considered as a probabilistic criterion and a new method is proposed to calculate this index in the presence of interruptible load. The reliability-constrained unit commitment (RCUC) problem is formulated based on the mixed-integer programming (MIP) method that can be solved using large-scale commercial solvers. The effectiveness of the proposed formulation is examined using the IEEE-RTS. Numerical results are presented and the implementation issues are discussed. A number of analyses are examined to evaluate the impact of some important factors on the problem solution. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
13. Weighting Method for Transient Analysis of Underground Cables.
- Author
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Kocar, Ilhan, Mahseredjian, Jean, and Olivier, Guy
- Subjects
ELECTROMAGNETIC devices ,ELECTROMAGNETIC compatibility ,ELECTROMAGNETIC interference ,ELECTRIC power distribution ,ELECTRIC power systems ,ELECTRIFICATION ,ELECTRICAL engineering ,ENGINEERING ,ELECTRICITY - Abstract
Accurate computation of electromagnetic transients for underground cables and overhead transmission lines requires the frequency domain characterization of two matrix functions: propagation and characteristic admittance. The propagation function constitutes a high order Wideband system with inherent time delays. In this paper a weighted fitting technique is presented and advocated for the identification of the propagation function as a rational transfer function. The paper also contributes to theoretical clarifications on vector fitting and orthonormal vector fitting. The application of orthonormal vector fitting is demonstrated together with weighted vector fitting. Although the presentation is also applicable to transmission lines, the numerical examples are focused on underground cables where the frequency dependency problems are more complex. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
14. Optimal Capacitor Allocation in a Distribution System Considering Operation Costs.
- Author
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Park, Jong-Young, Jin-Man Sohn, and Park, Jong-Keun
- Subjects
CAPACITORS ,DIELECTRIC devices ,ELECTRIC capacity ,ELECTRIC power ,POWER resources ,ELECTRICITY ,GENETIC algorithms ,COMBINATORIAL optimization ,ENGINEERING ,MATHEMATICS - Abstract
This paper proposes the planning method for capacitor installation in a distribution system to reduce the installation costs and minimize the loss of electrical energy. The expected life-time of devices with moving parts depends on the total number of operations, which affects the replacement period and replacement decisions for aging equipment under a limited budget. In this paper, the expected device lifetimes are included in the formulation, and the optimal operation status of the devices is determined using a genetic algorithm. The optimal numbers and locations for capacitor installation are determined based on the optimal operation status. Simulation results in a 69-bus distribution system show that the proposed technique performs better than conventional methods. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
15. Multiobjective Optimization for DG Planning With Load Models.
- Author
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Singh, Deependra, Singh, Devender, and Verma, K. S.
- Subjects
ELECTRICAL load ,ELECTRICITY ,ELECTRIC power ,GENETIC algorithms ,COMBINATORIAL optimization ,DISTRIBUTION (Probability theory) ,POWER resources ,MATHEMATICS ,ENGINEERING - Abstract
This paper presents a multiobjective performance index-based size and location determination of distributed generation in distribution systems with different load models. Normally, a constant power (real and reactive) load model is assumed in most of the studies made in the literature. It is shown that load models can significantly affect the optimal location and sizing of distributed generation (DG) resources in distribution systems. The simulation technique based on genetic algorithms is studied. The studies have been carried out on 16-bus and 37-bus distribution systems. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
16. Scheduling of Head-Sensitive Cascaded Hydro Systems: A Nonlinear Approach.
- Author
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Catalão, J. P. S., Mariano, S. J. P. S., Mendes, V. M. F., and Ferreira, L. A. F. M.
- Subjects
WATER power ,NATURAL resources ,RENEWABLE energy sources ,POWER resources ,ELECTRIC power production ,ELECTRICITY ,ENGINEERING ,MATHEMATICS - Abstract
In this paper, we propose a novel nonlinear approach to solve the short-term hydro scheduling problem under deregulation, considering head-dependency. The actual size of hydro systems, the continuous reservoir dynamics and constraints, the hydraulic coupling of cascaded hydro systems, and the complexity associated with head-sensitive hydroelectric power generation still pose a real challenge to the modelers. These concerns are all accounted for in our approach. Results from a case study based on one of the main Portuguese cascaded hydro systems are presented, showing that the proposed nonlinear approach is proficient. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
17. The Spanish AGC System: Description and Analysis.
- Author
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Egido, Ignacio, Fernández-Bernal, Fidel, and Rouco, Luis
- Subjects
SIMULATION methods & models ,CONFIGURATIONS (Geometry) ,WAVE functions ,ELECTRICITY ,ENGINEERING ,MATHEMATICS - Abstract
This paper describes and analyzes the Spanish AGC system. The differences with respect to a standard hierarchical structure are explained. A simple model useful for simulation is proposed. Using this model, the performance of the system and the influence of several parameters in system response is evaluated. The paper also suggests some changes in the configuration and parameter settings of the system to improve its performance. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
18. A Wide-Band Multi-Port System Equivalent for Real-Time Digital Power System Simulators.
- Author
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Xi Lin, Gole, A. M., and Ming Yu
- Subjects
ELECTRICITY ,ELECTRIC power ,ELECTROMAGNETIC devices ,ELECTRIC transients ,ELECTRIC currents ,ALGORITHMS ,DIGITAL computer simulation ,ENGINEERING ,MATHEMATICS - Abstract
This paper describes a method of developing wide-band multi-port system equivalents for use with real-time digital power system simulators. The proposed equivalent combines a frequency dependent network equivalent (FDNE) for the high frequency electromagnetic transients and a transient stability analysis (TSA) type simulation block for the electromechanical transients. The frequency dependent characteristic for FDNE is obtained by curve-fitting frequency domain admittance characteristics using the vector fitting method. The paper also introduces an approach for approximating the frequency dependent characteristic of large power networks from readily available typical power-flow data. The paper shows how the TSA algorithm can be adapted to a real-time platform. The validity of this method is confirmed with examples, including the study of a multi infeed HVDC system based network. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
19. Robust .Design of a TCSC Oscillation Damping Controller in a Weak 500-kV Interconnection Considering Multiple Power Flow Scenarios and External Disturbances.
- Author
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Simões, Alberto Mota, Savelli, Diego Chaves, Pellanda, Paulo César, Martins, Nelson, and Apkarian, Pierre
- Subjects
OSCILLATIONS ,ELECTRICITY ,ELECTRIC power ,THYRISTORS ,ELECTRIC switchgear ,ENGINEERING ,MATHEMATICS ,ALGORITHMS ,NONSMOOTH optimization - Abstract
The power oscillation damping (POD) controllers implemented in the two thyristor controlled series compensators of the Brazilian North-South (NS) interconnection, in the year 1999, were solely intended to damp the low-frequency NS oscillation mode. These controllers are still under operation and are derived from the modulus of the active power flow in the NS line that is phase-lagged at the frequency of the NS mode and may experience relatively large excursions generated by exogenous disturbances. This paper utilizes the same 1999 data to compare the performance of a proposed robust POD controller design with those of two conventional designs. A recent robust control synthesis algorithm used in this work is based on a nonsmooth optimization technique and has the capability to handle various controller structures, including reduced-order, and to deal with time-domain constraints on both controlled and measured outputs. Moreover, the nonsmooth design technique encompasses multiple operating conditions subject to various test signals, hence building a truly time-domain multi-scenarios approach. According to the results discussed hereafter, this is a key advantage in the industrial context of increasing demand for performance and robustness. The described results relate to a large-scale system model used in the feasibility studies for that interconnection. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
20. Power System Risk Assessment and Control in a Multiobjective Framework.
- Author
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Fei Xiao and McCalley, James D.
- Subjects
RISK assessment ,ELECTRIC power ,ENGINEERING ,MATHEMATICS ,ELECTRICITY ,PROBABILITY theory ,COST ,ELECTRIC potential ,DECISION making ,ALGORITHMS - Abstract
Traditional online security assessment determines whether the system is secure or not, but how secure or insecure is not explicitly indicated. This paper develops probabilistic indices, risk, to assess real-time power system security level. Risk captures not only event likelihood, but also consequence. System security level associated with low voltage and overload can be optimally controlled, using the NSGA multiobjective optimization method. A security diagram is used to visualize operating conditions in a way that enables both risk-based and traditional deterministic views. An index for cascading overloads is used to evaluate the Pareto optimal solutions. This paper shows that the multiobjective approach results in less risky and less costly operating conditions, and it provides a practical algorithm for implementation. The IEEE 24-bus RTS-1996 system is analyzed to show that risk-based system security control results in lower risk, lower cost, and less exposure to cascading outages. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
21. Mitigation of Subsynchronous Resonance in a Series-Compensated Wind Farm Using FACTS Controllers.
- Author
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Varma, Rajiv K., Auddy, Soubhik, and Semsedini, Ysni
- Subjects
ELECTRIC power factor ,ELECTRIC controllers ,ELECTROMAGNETIC interference ,ELECTRIC power distribution ,ELECTRIC power systems ,ELECTRIFICATION ,ELECTRICAL engineering ,ENGINEERING ,ELECTRICITY - Abstract
The rapid growth of wind power systems worldwide will likely see the integration of large wind farms with electrical networks that are series compensated for ensuring stable transmission of bulk power. This may potentially lead to subsynchronous-resonance (SSR) issues. Although SSR is a well-understood phenomenon that can be mitigated with flexible ac transmission system (FACTS) devices, scant information is available on the SSR problem in a series-compensated wind farm. This paper reports the potential occurrence and mitigation of SSR caused by an induction-generator (IG) effect as well as torsional interactions, in a series-compensated wind farm. SSR suppression is achieved as an additional advantage of FACTS controllers which may already be installed in the power system for achieving other objectives. In this study, a wind farm employing a self-excited induction generator is connected to the grid through a series-compensated line. A static var compensator (SVC) with a simple voltage regulator is first employed at the IG terminal in addition to the fixed shunt capacitor for dynamic reactive power support. The same SVC is shown to effectively damp SSR when equipped with an SSR damping controller. Also, a thyristor-controlled series capacitor (TCSC) that is actually installed to increase the power transfer capability of the transmission line is also shown to damp subsynchronous oscillations when provided with closed-loop current control. While both FACTS controllers--the SVC and TCSC--can effectively mitigate SSR, the performance of TCSC is shown to be superior. Extensive simulations have been carried out using EMTDC/PSCAD to validate the performance of SVC and TCSC in damping SSR. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
22. A Computational Approach to Optimal Damping Controller Design for a GCSC.
- Author
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Ray, Swakshar, Venayagamoorthy, Ganesh Kumar, and Watanabe, Edson H.
- Subjects
INTERCONNECTED power systems ,MATHEMATICAL optimization ,ELECTRIC power distribution ,ELECTRIC power factor ,ELECTRIC controllers ,ELECTRIC power systems ,ELECTRIFICATION ,ELECTRICAL engineering ,ENGINEERING ,ELECTRICITY - Abstract
This paper presents a computational approach for an offline measurement-based design of an optimal damping controller using adaptive critics for a new type of flexible ac transmission system device--the gate-controlled series capacitor (GCSC). Remote measurements are provided to the controller to damp out system modes. The optimal controller is developed based on the heuristic dynamic programming (HDP) approach. Three multilayer-perceptron neural networks are used in the design--the identifier/model network to identify the dynamics of the power system, the critic network to evaluate the performance of the damping controller, and the controller network to provide optimal damping. This measurement-based technique provides an alternative to the classical linear model-based optimal control design. The eigenvalue analysis of the closed-loop system is performed with time-domain responses using the Prony method. An analysis of the simulation results shows potential of the HDP-based optimal damping controller on a GCSC for enhancing the stability of the power system. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
23. Dead-Time Issues in Predictive Current Control.
- Author
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Summers, Terrence J. and Betz, Robert E.
- Subjects
ELECTRONIC systems ,ELECTRONIC equipment ,ENGINEERING ,ELECTRICITY ,ALGORITHMS ,ELECTRONICS - Abstract
Current control in inverter-driven machine systems is the inner most component of the hierarchy of control loops. If the control of current in the machine is not fast and accurate then it is difficult, if not impossible, to build a high-performance drive system. Unfortunately, the implementation of current control in power electronic systems is not ideal. Practical effects can have a significant influence on its performance. This paper examines one of these effects, dead time, and considers the influence it has on the performance of predictive current controllers (PCCs). The paper presents analysis that shows that a PCC implicitly compensates for voltage loss due to dead time. Also, a modified PCC is introduced that reduces the zero-current-clamp problem caused by dead time. Simulation and experimental results are presented to verify the analysis and confirm the performance of the new algorithm. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
24. Adaptive Hybrid Genetic Algorithm for Technical Loss Reduction in Distribution Networks Under Variable Demands.
- Author
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Queiroz, Leonardo M. O. and Lyra, Christiano
- Subjects
ALGORITHMS ,MATHEMATICS ,ENGINEERING ,ELECTRIC power distribution ,POWER transmission ,POWER resources ,ELECTRICITY ,ELECTRIC transients ,MATHEMATICAL optimization - Abstract
In power distribution networks the load varies within any given time frame. It may, therefore, seem that a good approach to reduce losses would be the solving of a network reconfiguration problem to suit each of the significant load variations. However, frequent changes in configuration can trigger outages or cause transient problems; they are best avoided. A recent formulation of this problem explicitly considers load variations and proposes to restrain frequent reconfigurations by assuming that network topologies will remain unchanged for a given planning period. This formulation leads to a much larger optimization problem than that traditionally used for network reconfiguration; moreover, it requires a new approach to optimization which is capable of dealing with energy flows instead of only instantaneous power flows. Such an approach is proposed in this paper, which discusses the design of an adaptive hybrid genetic algorithm that fulfills these new requirements. Key concepts in evolutionary computation and analysis of distribution systems are explored to develop this new algorithm. Application to real case studies certifies its benefits. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
25. Flexible Transmission Expansion Planning With Uncertainties in an Electricity Market.
- Author
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Jun Hua Zhao, Zhao Yang Dong, Lindsay, Peter, and Kit Po Wong
- Subjects
DEREGULATION ,ENERGY industries ,ELECTRIC power ,POWER resources ,ELECTRICITY ,NONLINEAR programming ,MATHEMATICAL programming ,MATHEMATICS ,ENGINEERING - Abstract
Deregulation of the electric power industry has introduced new uncertainties for market participants and made planning of transmission expansion more difficult. More flexible transmission expansion plans are needed, to cope with the increased risks. In this paper, a novel planning approach is proposed to meet the above challenge. In our approach, the planning process is modeled as a mixed integer nonlinear programming (MINLP) problem, so that conflicting objectives can be optimized simultaneously. To minimize planning risks, our method identifies several scenarios based on statistics and expert knowledge; the most flexible expansion plan is selected as the plan that has least adaptation cost. The proposed method is tested with the IEEE 14-bus system. Promising results are obtained to demonstrate the effectiveness of our method. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
26. An Annual Midterm Energy Forecasting Model Using Fuzzy Logic.
- Author
-
Elias, Charalambos N. and Hatziargyriou, Nikos D.
- Subjects
FUZZY logic ,MATHEMATICAL logic ,FUZZY systems ,MATHEMATICS ,ENGINEERING ,ELECTRIC power ,POWER resources ,ELECTRICITY ,BIOLOGICAL neural networks ,ARTIFICIAL intelligence - Abstract
The objective of this paper is to present a new fuzzy logic method for midterm energy forecasting. The proposed method properly transforms the input variables to differences or relative differences, in order to predict energy values not included in the training set and to use a minimal number of patterns. The input variables, the number of the triangular membership functions and their base widths are simultaneously selected by an optimization process. The standard deviation is calculated analytically by mathematical expressions based on the membership functions. Results from an extensive application of the method to the Greek power system and for different categories of customers are compared to those obtained from the application of standard regression methods and artificial neural networks (ANN). [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
27. Application of NSGA-II Algorithm to Generation Expansion Planning.
- Author
-
Kannan, S., Baskar, S., McCalley, James D., and Murugan, P.
- Subjects
GENETIC algorithms ,COMBINATORIAL optimization ,MATHEMATICS ,ENGINEERING ,DECISION making ,INVESTMENTS ,COST ,POWER resources ,ELECTRICITY - Abstract
This paper describes use of a multiobjective optimization method, elitist nondominated sorting genetic algorithm version II (NSGA-II), to the generation expansion planning (GEP) problem. The proposed model provides for decision maker choice from among the different trade-off solutions. Two different problem formulations are considered. In one formulation, the first objective is to minimize cost; the second objective is to minimize sum of normalized constraint violations. In the other formulation, the first objective is to minimize investment cost; the second objective is to minimize outage cost (or maximize reliability). Virtual mapping procedure is introduced to improve the performance of NSGA-II. The GEP problem considered is a test system for a six-year planning horizon having five types of candidate units. The results are compared and validated. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
28. Fuzzy Logic Supervisor-Based Primary Frequency Control Experiments of a Variable-Speed Wind Generator.
- Author
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El Mokadem, Mostafa, Courtecuisse, Vincent, Saudemont, Christophe, Robyns, Benoit, and Deuse, Jacques
- Subjects
FUZZY logic ,MATHEMATICAL logic ,FUZZY systems ,VARIABLE speed generators ,ELECTRIC generators ,ELECTRICITY ,POWER resources ,MATHEMATICS ,ENGINEERING - Abstract
In this paper, a primary frequency control strategy based on fuzzy logic, designed for variable-speed wind generators, is proposed and tested on a 2.2-kW test bench. The fuzzy logic supervisor ensures a regular primary reserve for a large range of wind speeds without any wind speed measurement. This supervisor controls simultaneously the generator torque and the pitch angle to keep the primary reserve; it determines in real time the generator power reference value. The fuzzy logic supervisor is compared to a simpler strategy, based only on the control of the generator torque. This classical strategy ensures a regular power reserve only when the wind generator operates at full load, and the generator power reference needs to be determined previously or by the network manager. A procedure for implementing a fuzzy logic supervisor in real time is proposed. The experiments indicate the regularity of the power reserve and the ability to contribute to frequency control. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
29. Identification of Catastrophic Failures in Power System Using Pattern Recognition and Fuzzy Estimation.
- Author
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Hazra, Jagabondhu and Sinha, Avinash K.
- Subjects
ELECTRIC power systems ,ELECTRICITY ,POWER resources ,PROBABILITY theory ,DATABASES ,MATHEMATICAL decoupling ,MATHEMATICAL inequalities ,ENGINEERING ,MATHEMATICS - Abstract
This paper presents a new approach for finding the sequence of events that may lead to catastrophic failure in a power system. The probable sequences (of events) leading to catastrophic failures are identified using risk indices which incorporate the severity as well as the probability of the contingencies. Probable collapse sequences are identified offline for different possible loading conditions using a modified fast decoupled load flow method which considers the voltage and frequency dependence of loads and generator regulation characteristics and stored in a knowledge base. Pattern recognition method and fuzzy estimation are used for online identification of collapse sequences for any operating condition from the stored database (knowledge base). [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
30. An Improved UPFC Control for Oscillation Damping.
- Author
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Guo, J., Crow, M. L., and Sarangapani, Jagannathan
- Subjects
POWER resources ,ELECTRICITY ,ELECTRIC power systems ,OSCILLATIONS ,FLUCTUATIONS (Physics) ,ELECTRIC power production ,ENGINEERING - Abstract
This paper proposes a new control approach for a unified power flow controller (UPFC) for power system oscillation damping. This control is simple to implement, yet is valid over a wide range of operating conditions. It is also effective in the presence of multiple modes of oscillation. The proposed control is implemented in several test systems and is compared against a traditional PI control. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
31. The Dead Band Control of LTC Transformer at Distribution Substation.
- Author
-
Joon-Ho Choi and Seung-Il Moon
- Subjects
ALGORITHMS ,ELECTRIC potential ,POWER resources ,ELECTRICITY ,ELECTRIC power ,ELECTRIC transformers ,CONSUMERS ,ENGINEERING ,MATHEMATICS - Abstract
In this paper, dead band control algorithms using a performance index of the load tap changing (LTC) tap position are proposed to reduce the tap changing operation times. The performance index is defined as the customer voltage quality with the tap position of LTC transformer. In addition, dead band control algorithms using the load diversity values of the feeders are proposed. The mathematical formulations of the proposed dead band control algorithms are introduced. A sample case study is shown to verify the effectiveness of the proposed dead band control algorithms. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
32. Design of the Optimal ULTC Parameters in Distribution System With Distributed Generations.
- Author
-
Miyoung Kim, Hara, Ryoichi, and Kita, Hiroyuki
- Subjects
ELECTRIC power ,POWER resources ,ELECTRICITY ,DISTRIBUTED power generation ,ELECTRIC power production ,DISTRIBUTED resources (Electric utilities) ,ELECTRIC potential ,CONSUMERS ,ENGINEERING - Abstract
In order that the supply of electric power remain stable and sustainable, a certain level of power quality must be maintained while securing energy resources and resolving environmental issues. The distributed generation (DG) has become an essential and indispensable element of such distribution systems from both an environmental and an energy security perspective. However, the installation of DGs in distribution systems may cause variations of voltage on distribution feeder because the DG power outputs may change randomly and dramatically. Generally, the sending voltage at substation in distribution systems can be regulated by an under load tap changer (ULTC) designed to maintain customers' receiving voltages within a predetermined range. Voltage regulation performed by ULTC calls for two parameters: the equivalent impedance and the load center voltage. Therefore, in distribution networks with DG interconnections, these parameters should be designed with attention not only to load variations but also to DG outputs. This paper proposes a method for designing ULTC parameters with reference to variations in DG output. The proposed algorithm is tested with IEEE 13-node system and Korean model network. The results demonstrate the validity of the proposed design method for varying DG distribution. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
33. Day-Ahead Price Forecasting of Electricity Markets by Mutual Information Technique and Cascaded Neuro-Evolutionary Algorithm.
- Author
-
Amjady, Nima and Keynia, Farshid
- Subjects
ELECTRICITY ,ELECTRIC power ,POWER resources ,PRICES ,ALGORITHMS ,ECONOMIC competition ,ARTIFICIAL neural networks ,ARTIFICIAL intelligence ,ENGINEERING - Abstract
In a competitive electricity market, price forecasts are important for market participants. However, electricity price is a complex signal due to its nonlinearity, nonstationarity, and time variant behavior. In spite of much research in this area, more accurate and robust price forecast methods are still required. In this paper, a combination of a feature selection technique and cascaded neuro-evolutionary algorithm (CNEA) is proposed for this purpose. The feature selection method is an improved version of the mutual information (MI) technique. The CNEA is composed of cascaded forecasters where each forecaster consists of a neural network (NN) and an evolutionary algorithm (EA). An iterative search procedure is also incorporated in our solution strategy to fine-tune the adjustable parameters of both the MI technique and CNEA. The price forecast accuracy of the proposed method is evaluated by means of real data from the Pennsylvania-New Jersey-Maryland (PJM) and Spanish electricity markets. The method is also compared with some of the most recent price forecast techniques. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
34. Distributed Transient Stability Simulation of Power Systems Based on a Jacobian-Free Newton-GMRES Method.
- Author
-
Ying Chen, Chen Shen, and Jian Wang
- Subjects
JACOBIAN matrices ,FUNCTIONS of several complex variables ,ELECTRIC power ,ELECTRICITY ,ALGORITHMS ,ENGINEERING ,MATHEMATICS ,STOCHASTIC convergence ,MATHEMATICAL functions - Abstract
As power systems becoming more closely interconnected and are being deregulated in energy markets, distributed simulations among different dispatch centers are highly required for online full system analysis and control applications. In this paper a new algorithm for distributed transient stability simulation of interconnected power systems is presented. Based on a Jacobian-free Newton-GMRES(m) method, this algorithm requires only exchanges of states of boundary buses among different regions. Therefore, it has strong scalability in distributed computing environments built on heterogeneous computing resources. Moreover, several accelerating methods are developed to enhance its efficiency, including continuous preconditioning with adaptive preconditioners, predicting boundary conditions and multistep coordination. The standard IEEE 39-bus system and a real power system with 1165 buses were used as test systems. The test results show that these accelerating methods greatly enhance the convergence rate of the proposed algorithm and reduce communication costs remarkably, which proves the novel algorithm is feasible and can be adopted in wide area networks with high-latency. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
35. Induction Machine Modeling Based on Shifted Frequency Analysis.
- Author
-
Peng Zhang, Martí, José R., and Dommel, Hermann W.
- Subjects
ELECTROMAGNETISM ,ELECTROMAGNETIC induction ,ELECTRIC power ,ELECTRICITY ,EQUATIONS ,TRANSIENTS (Dynamics) ,MACHINERY ,ENGINEERING ,MATHEMATICS - Abstract
Electromagnetic transient program (EMTP) simulators are being widely used in power system dynamics studies. However, their capability in real-time simulation of power systems is compromised due to the small time step used and relatively slow simulation speed. The shifted frequency analysis (SFA) is then proposed to accelerate the EMTP simulations for power system dynamics. The objective of this paper is to extend the SFA method [7] to model the induction machines in EMTP. By analyzing the relationship between rotor and stator physical variables, a phase-coordinate model with lower number of equations is first derived. Based on this, an SFA model is proposed as a general purpose model capable of simulating both fast transients and slow dynamics. Case study results have confirmed the SFA induction machine model is a valuable component for real-time EMTP simulations. It is observed that the SFA model is in excess of 70 times faster than the standard EMTP model when simulating dynamics with frequency spectra close to the fundamental power frequency. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
36. Identifying Power Flow Control Infeasibilities in Large-Scale Power System Models.
- Author
-
Filho, João A. Passos, Martins, Nelson, and Falcão, Djalma M.
- Subjects
ELECTRIC power ,ELECTRICITY ,ENGINEERING ,MATHEMATICS ,STOCHASTIC convergence ,MATHEMATICAL functions ,EIGENVALUES ,MATRICES (Mathematics) ,JACOBIAN matrices - Abstract
This paper describes a methodology to identify potential conflicts among power flow control devices that may slow down or impair convergence. The proposed methodology is based on the eigenvalue analysis of the sparse Jacobian matrix associated with the Newton power flow with controls. Practically identical results are obtained from a smaller control sensitivity matrix. The implementation in a power flow program has been tested using both small- and large-scale systems. The results presented validate and clearly indicate the effectiveness of the proposed technique. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
37. Detection of Flicker Caused by Interharmonics.
- Author
-
Taekhyun Kim, Powers, Edward J., Grady, W. Mack, and Arapostathis, Ari
- Subjects
BANDPASS filters ,FLICKER fusion ,ELECTRIC filters ,LIGHT sources ,LIGHTING ,ELECTRICAL engineering ,ENGINEERING ,ELECTRICITY ,ELECTRIC appliance protection ,ELECTRONICS - Abstract
International standard bodies have specified an instrument capable of detecting and assessing the severity of lighting flicker, which is called a flickermeter. However, a deficiency with regard to flicker caused by high-frequency interharmonics has been reported in the recent literature. In this paper, another deficiency of the International Electrotechnical Commission (IEC) flickermeter with regard to low-frequency interharmonics, whose frequencies are below the difference between the fundamental frequency and the cutoff frequency of a bandpass filter of the IEC standard flickermeter, will be discussed and illustrated based on analysis and numerical experiments. A new approach based on down-up sampling in the discrete-time sample domain is also proposed to address the flicker-detection problem associated with interharmonics. We demonstrate the efficacy of the proposed method by a comparison with the current flickermeter standard in the presence of interharmonics. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
38. Effect of Sampling Frequency and Harmonics on Delay-Based Phase-Sequence Estimation Method.
- Author
-
Bongiorno, Massimo, Svensson, Jan, and Sannino, Ambra
- Subjects
ELECTRIC power distribution ,ELECTRIC power factor ,ELECTRIC controllers ,ELECTROMAGNETIC interference ,ELECTRIC power systems ,ELECTRIFICATION ,ELECTRICAL engineering ,ENGINEERING ,ELECTRICITY - Abstract
This paper investigates issues related to practical implementation of the one-quarter of cycle-based estimation method [here called delayed signal cancellation (DSC)] for online detection of positive and negative sequence components of three-phase quantities. The detection error due to non-ideal sampling frequency is calculated. Furthermore, the effect of the DSC method on estimation when harmonic components are present in the input signal is analyzed. It is shown how harmonics transfer through the DSC and how a non-ideal sampling frequency affects the estimation of the harmonics. Experimental verification of the analytical results is presented. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
39. Thermal Runaway Characteristics of Bi2212 Coil for Conduction-Cooled SMES.
- Author
-
Kojima, Hiroki, Hayakawa, Naoki, Noguchi, Shinki, Endo, Fumihiro, Hirano, Naoki, Nagaya, Shigeo, and Okubo, Hitoshi
- Subjects
ANALYTICAL chemistry ,FERROMAGNETIC material fluctuations ,TEMPERATURE ,ELECTRIC potential ,HEAT radiation & absorption ,TECHNOLOGY ,ENGINEERING ,ELECTRICITY - Abstract
In this paper, we investigated the thermal runaway characteristics of a conduction-cooled Bi2212 HTS coil with a 4 K-GM cryocooler system under compensating operation for load fluctuations. We measured the temporal evolutions of temperature and voltage distributions of the HTS solenoidal coil for typical current patterns of load fluctuation compensation at different ambient temperatures. On the basis of these experimental results, we constructed a thermal analysis model, and analysed the thermal runaway characteristics during and after the load fluctuation compensation. Based on the results of our experiments and the numerical simulations, we proposed criterion for the monitoring of an HTS SMES system during compensating operation for load fluctuations. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
40. Variance Analysis of Frequency Response Function Measurements Using Periodic Excitations.
- Author
-
D'haene, Tom, Pintelon, Rik, Schoukens, Johan, and Van Gheem, Els
- Subjects
FREQUENCIES of oscillating systems ,ELECTRICAL engineering ,OSCILLATIONS ,VIBRATION (Mechanics) ,ENGINEERING ,ELECTRICITY - Abstract
The influence of disturbing noise and nonlinear distortions on frequency response function measurements using periodic excitations has been studied in detail in the literature. A variance analysis method has been developed that allows one to detect and quantify the nonlinear distortions and the disturbing noise. In this paper, the variance analysis is generalized to detect and quantify the following nonstationary disturbances: 1) nonsynchronous periodic signals, for example, the 50 Hz mains and its harmonics, and 2) nonstationary behavior of the device under test, for example, phase or frequency modulation. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
41. Characterization of Human Metal ESD Reference Discharge Event and Correlation of Generator Parameters to Failure Levels -- Part II: Correlation of Generator Parameters to Failure Levels.
- Author
-
Kai Wang, Pommerenke, David, Chundru, Ramachandran, Van Doren, Tom, Centola, Federico Plo, and Jiu Sheng Huang
- Subjects
COMPLEMENTARY metal oxide semiconductors ,ELECTRONICS ,ENGINEERING ,ELECTRICITY ,TECHNOLOGY ,PHYSICAL sciences - Abstract
Most electrostatic discharge (ESD) generators are built in accordance with the IEC 61000-4-2 specifications. It is shown, that the voltage induced in a small loop correlates with the failure level observed in an ESD failure test on the systems comprised of fast CMOS devices, while rise time and derivative of the discharge current did not correlate well. The electric parameters of typical ESD generators and ESD generators that have been modified to reflect the current and field parameters of the human metal reference event are compared and the effect on the failure level of fast CMOS electronics is investigated. The consequences of aligning an ESD standard with the suggestions of the first paper, of this two-paper series, are discussed with respect to reproducibility and test severity. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
42. Solution to Close-in Fault Problem in Directional Relaying.
- Author
-
Pradhan, A. K. and Jena, P.
- Subjects
ELECTRIC currents ,COMPUTER-aided design ,ELECTRIC transients ,ELECTRIC power factor ,ELECTRIC power distribution ,ELECTRIC power systems ,ELECTRIFICATION ,ELECTRICAL engineering ,ENGINEERING ,ELECTRICITY - Abstract
Directional relays use voltage as the polarizing quantity. When three-phase faults occur close to the relay bus, the available voltage becomes nearly zero and this creates a problem in estimation of the fault direction. The capacitor coupling voltage transformer subsidence transients add to this problem. The memory voltage used as the polarizing quantity at these situations is a compromise. This paper highlights these issues and proposes a simple solution using the power-flow direction in addition to other information. The performance of the technique is evaluated through simulation in Power System Computer Aided Design. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
43. New Challenges in Power System Restoration With Large Scale of Dispersed Generation Insertion.
- Author
-
Thi Thu Ha Pham, Bésanger, Yvon, and Hadjsaid, Nouredine
- Subjects
ELECTRIC power systems ,ELECTRICITY ,POWER resources ,ALGORITHMS ,DISTRIBUTION (Probability theory) ,MATHEMATICS ,ENGINEERING - Abstract
The ability of using dispersed generation (DG) in the distribution system restoration service in the context of smart networks is presented in this paper. The objectives are to reduce the consequences due to a major blackout in terms of the out-of-service load volume, and the duration of restoration process. Based on knapsack problem formulation and network represented graph modeling, a new restoration procedure for distribution network is proposed. An adapted branch-and-bound algorithm is then used to solve the problem. It maximizes the restored loads in distribution by using the DG availability. Simulation results on a study case will be shown to illustrate the proposed procedure and quantify the benefit of using DG in critical situations. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
44. Prediction of Power System Security Levels.
- Author
-
Halilčević, Suad S., Gubina, Ferdinand, and Gubina, Andrej F.
- Subjects
MARKOV processes ,STOCHASTIC processes ,MONTE Carlo method ,NUMERICAL analysis ,ELECTRIC power systems ,ELECTRICITY ,POWER resources ,ENGINEERING ,MATHEMATICS - Abstract
In the paper, Markov chains in conjunction with Monte Carlo simulation are used to predict the power system security level. The new approach uses a Markov chain for each identified security range to track the development of security level through time. Based on the forecasted and recorded data, the proposed procedure offers a useful tool to the system operator to predict a future power system security level. The method has been tested on the Bosnian power system using the recorded data on security levels during a one-year period. The forecasted results show a striking coincidence with the real security levels. By means of a simple and computationally fast method, the system operator can estimate the probability of a power system blackout. The presented method could be incorporated in the wide-area monitoring system in control centers. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
45. A Study on the Effect of Generation Shedding to Total Transfer Capability by Means of Transient Stability Constrained Optimal Power Flow.
- Author
-
Hakim, Lukmanul, Kubokawa, Junji, Yue Yuan, Mitani, Tomohisa, Zoka, Yoshifumi, Yorino, Naoto, Niwa, Yoshihito, Shimomura, Kimihiko, and Takeuchi, Akira
- Subjects
ELECTRIC transients ,ELECTRIC appliance protection ,POWER resources ,ELECTRICITY ,ELECTRIC power systems ,LAGRANGE equations ,DIFFERENTIAL equations ,ENGINEERING ,MATHEMATICS - Abstract
In nowadays deregulated market, total transfer capability (TTC) calculation, which is the basis for evaluating available transfer capability (ATC), has been becoming more significant. During the last decade, transient stability constraints have been included in the optimal power flow approach to maximize TTC. However, no previous work on investigating the effect of generation shedding action to TTC has been reported. Therefore, in this paper, we propose a TTC maximization by means of transient stability constrained optimal power flow considering the generation shedding action. Proper selection of the generator to shed is based on its Lagrange multiplier value of transient stability constraint. Our simulation results show how TTC can be increased to anticipate possible generation shedding. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
46. A Generic Operations Framework for Discos in Retail Electricity Markets.
- Author
-
Algarni, Ayed A. S. and Bhattacharya, Kankar
- Subjects
ELECTRICITY ,POWER resources ,ELECTRIC power ,ECONOMIC competition ,ELECTRIC industries ,DECISION making ,COST ,ENGINEERING ,MATHEMATICS - Abstract
A generic operations framework for a distribution company (disco) operating in a competitive electricity market environment is presented in this paper. The operations framework is a two-stage hierarchical model in which the first deals with disco's activities in the day-ahead stage, the Day Ahead Operations Model (DAOM). The second deals with disco's activities in real-time and is termed Real-Time Operations Model (RTOM). The DAOM determines the disco's operational decisions on grid purchase, scheduling of distributed generation (DG) units owned by it, and contracting for interruptible load. These decisions are imposed as boundary constraints in the RTOM and the disco seeks to minimize its short-term costs keeping in mind its day-ahead decisions. A case-study is presented considering the well-known 33-bus distribution system and three different scenarios are constructed to analyze the disco's actions and decision-making in this context. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
47. Decentralized Optimal Power Flow Control for Overlapping Areas in Power Systems.
- Author
-
Hug-Glanzmann, Gabriela and Andersson, Göran
- Subjects
POWER resources ,ELECTRICITY ,ELECTRIC power ,ELECTROMECHANICAL devices ,MATHEMATICAL physics ,ENGINEERING ,MATHEMATICS - Abstract
The task of controlling a power system is generally accomplished by several entities, each responsible for a distinct part of the system. For the enhancement of the system security, controllable devices such as FACTS devices are installed and operated by these entities. But in order to avoid conflicting behavior coordination is needed, leading to the concept of multiarea control. In this paper, it is assumed that the areas are determined independently from each other according to the influence of the control devices. As a consequence, overlapping areas may result necessitating an extension of the applied multiarea control method based on approximate Newton directions. In addition, it is taken into account that part of the grid might not be included in any of the areas. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
48. Assessment and Enhancement of Small Signal Stability Considering Uncertainties.
- Author
-
Rueda, José L., Colomé, Delia G., and Erlich, Istvan
- Subjects
PROBABILITY theory ,MONTE Carlo method ,STOCHASTIC processes ,NUMERICAL analysis ,ELECTRIC power ,ELECTRICITY ,OSCILLATIONS ,ENGINEERING ,MATHEMATICS - Abstract
This paper proposes a probabilistic small signal stability assessment (PSSSA) methodology based on the application of Monte Carlo approach for iterative evaluation, via modal analysis of small signal stability (SSS). Operation states represented by random values of generation and demand are analyzed. A probabilistic instability risk index based on cumulative probability distribution function of damping ratios of oscillatory modes is calculated, as well as a power system stabilizer (PSS) devices location index based on eigenvectors and participation factors, which are considered random variables. Moreover, the impact of long-distance power flows on oscillatory modes (OM) and how the damping of OM depends on the orientation and magnitude of power flows is investigated. Further, an additional index concerns qualitatively the determination of transfer capability as affected by small signal stability. PSSSA is tested on a reduced order model of New England-New York's interconnected system considering uncertainties around three different system conditions separately: highly loaded, fairly loaded, and lowly loaded. The results highlight the main advantages of PSSSA over deterministic SSS studies such as instability risk assessment, small signal stability enhancement through adequate PSS location, and the proposal of possible restrictions for transfer capability in order to avoid poorly damped oscillations in the face of the diversity in power system operation. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
49. Investigation of StatComs With Capacitive Energy Storage for Reduction of Voltage Phase Jumps in Weak Networks.
- Author
-
Hailian Xie, Ängquist, Lennart, and Nee, Hans-Peter
- Subjects
ENERGY storage ,ELECTRIC power supplies to apparatus ,POWER (Mechanics) ,FORCE & energy ,ELECTRIC potential ,FLUCTUATIONS (Physics) ,ELECTRICITY ,ENGINEERING ,MATHEMATICS - Abstract
The voltage at the point of common coupling (PCC) in a weak network is very sensitive to load changes. A sudden change in active load will cause both a phase jump and a magnitude fluctuation in the bus voltage (voltage at the PCC), whereas reactive load changes mainly affect the voltage magnitude. With the addition of energy storage to a static synchronous compensator (StatCom), it is possible to compensate for the active power change as well as providing reactive power support. In this paper effective active power compensation schemes are proposed. Simulation and experimental results verify the compensation schemes by showing that a StatCom with energy storage can significantly reduce phase jumps and magnitude deviations of the bus voltage under load disturbances. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
50. Wide-Area Measurements-Based Two-Level Control Design Considering Signal Transmission Delay.
- Author
-
Dotta, Daniel, e Silva, Aguinaldo S., and Decker, Ildemar C.
- Subjects
ELECTRIC power ,ELECTRICITY ,TIME delay systems ,STOCHASTIC convergence ,COMMUNICATION ,MATRICES (Mathematics) ,ENGINEERING ,MATHEMATICS - Abstract
In this paper the design of power system stabilizers for small-signal stability using phasor measurements is considered. An approach based on optimal control with structural constraints is proposed to design a two-level control structure. Time delays are included in the design. The method is combined with order reduction to ensure faster convergence of the design algorithm and to facilitate the choice of the weighting matrices for damping inter-area modes. The control scheme is discussed and modal analysis and time-domain simulations of two Brazilian equivalent systems are performed to assess the control performance. The robustness to loss of communication links, topological changes, and variations of time delay is evaluated. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
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