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Power Systems, IEEE Transactions on

Issue 2 • Date May 2008

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Displaying Results 1 - 25 of 73
  • Table of contents

    Publication Year: 2008 , Page(s): C1 - 258
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    Freely Available from IEEE
  • IEEE Transactions on Power Systems publication information

    Publication Year: 2008 , Page(s): C2
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    Freely Available from IEEE
  • A Variable Partitioning Strategy for the Multirate Method in Power Systems

    Publication Year: 2008 , Page(s): 259 - 266
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (234 KB) |  | HTML iconHTML  

    An application of the multirate method to differential and algebraic equations (DAEs) is discussed in this paper. Based on the specific formulation of the power systems algebraic equations, an effective algebraic variable partitioning strategy is developed and implemented. The application of the partitioning strategy to an example power system provides validation of the proposed partitioning strategy in terms of speed-up and accuracy. View full abstract»

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  • A Statistical Approach for Interval Forecasting of the Electricity Price

    Publication Year: 2008 , Page(s): 267 - 276
    Cited by:  Papers (32)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (946 KB) |  | HTML iconHTML  

    Electricity price forecasting is a difficult yet essential task for market participants in a deregulated electricity market. Rather than forecasting the value, market participants are sometimes more interested in forecasting the prediction interval of the electricity price. Forecasting the prediction interval is essential for estimating the uncertainty involved in the price and thus is highly useful for making generation bidding strategies and investment decisions. In this paper, a novel data mining-based approach is proposed to achieve two major objectives: 1) to accurately forecast the value of the electricity price series, which is widely accepted as a nonlinear time series; 2) to accurately estimate the prediction interval of the electricity price series. In the proposed approach, support vector machine (SVM) is employed to forecast the value of the price. To forecast the prediction interval, we construct a statistical model by introducing a heteroscedastic variance equation for the SVM. Maximum likelihood estimation (MLE) is used to estimate model parameters. Results from the case studies on real-world price data prove that the proposed method is highly effective compared with existing methods such as GARCH models. View full abstract»

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  • Contingency-Based Zonal Reserve Modeling and Pricing in a Co-Optimized Energy and Reserve Market

    Publication Year: 2008 , Page(s): 277 - 286
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (345 KB) |  | HTML iconHTML  

    Ancillary service markets are a very important part of the standard market design and are under development or implementation on a centralized basis in major U.S. electricity markets. This paper presents the market clearing framework for the co-optimized real-time energy-reserve market that has been developed and implemented in the ISO New England (ISO NE). In this co-optimized market clearing model, reserve products are procured on a zonal basis to satisfy the first and the second contingency protection criteria required by the ISO NE's real-time operations for both the entire area and typical import-constrained areas. The proposed zonal reserve model is derived from simulating each contingency event in the predefined reserve zones. Differing from standard industrial practices, the proposed zonal reserve model recognizes reserve deliverability for nested reserve zones and allocates the zonal total transfer capability between energy and reserves in an economic way. Numerical examples for a two-zone system are presented to demonstrate the validity of this modeling technique. View full abstract»

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  • Risk-Based Allocation of Distribution System Maintenance Resources

    Publication Year: 2008 , Page(s): 287 - 295
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (592 KB) |  | HTML iconHTML  

    Asset management is an important activity in present day distribution system planning and operation. Utilities are constantly striving to optimize the use of resources available for maintenance while ensuring system reliability is within satisfactory limits. This paper proposes a method to allocate maintenance resources to various distribution system assets. To determine the effects of maintenance, a predictive reliability assessment tool is developed. This paper describes the model on which this tool is based. The results obtained from reliability assessment can be used along with an optimizer to allocate resources to various maintenance tasks in a distribution system. View full abstract»

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  • m-k Robust Observability in State Estimation

    Publication Year: 2008 , Page(s): 296 - 305
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (870 KB) |  | HTML iconHTML  

    This paper provides a technique to determine the minimum required measurement set to ensure observability in state estimation even if any meters fail. The technique relies on solving a nonlinear integer programming problem. The proposed procedure is illustrated through a simple example and three case studies based on the IEEE Test Systems. Conclusions are finally drawn. View full abstract»

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  • Stochastic Security for Operations Planning With Significant Wind Power Generation

    Publication Year: 2008 , Page(s): 306 - 316
    Cited by:  Papers (161)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (397 KB) |  | HTML iconHTML  

    In their attempt to cut down on greenhouse gas emissions from electricity generation, several countries are committed to install wind power generation up to and beyond the 10%-20% penetration mark. However, the large-scale integration of wind power represents a challenge for power system operations planning because wind power 1) cannot be dispatched in the classical sense; and 2) its output varies as weather conditions change. This warrants the investigation of alternative short-term power system operations planning methods capable of better coping with the nature of wind generation while maintaining or even improving the current reliability and economic performance of power systems. To this end, this paper formulates a short-term forward electricity market-clearing problem with stochastic security capable of accounting for nondispatchable and variable wind power generation sources. The principal benefit of this stochastic operation planning approach is that, when compared to a deterministic worst-case scenario planning philosophy, it allows greater wind power penetration without sacrificing security. View full abstract»

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  • Cournot Equilibrium Calculation in Power Networks: An Optimization Approach With Price Response Computation

    Publication Year: 2008 , Page(s): 317 - 326
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1612 KB) |  | HTML iconHTML  

    Since deregulated power markets are very often oligopolistic ones, efficient models that are able to describe strategic behavior of firms must be developed. In particular, transmission constraints can easily increase the opportunities of market players to exercise market power. This paper presents a model that describes the firms strategic interaction, based on Nash-Cournot equilibrium, when the power network is taken into account. Specifically, this paper introduces a new iterative algorithm, that explicitly considers how the production at a certain bus affects the whole network, and consequently models the opportunities for the firms of exercising market power, taking into account their ability to influence the composition of the set of constrained lines. The theoretical basis of the method as well as a case study based on the Central European network is included. View full abstract»

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  • Models for Quantifying the Economic Benefits of Distributed Generation

    Publication Year: 2008 , Page(s): 327 - 335
    Cited by:  Papers (44)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (244 KB) |  | HTML iconHTML  

    We examine some of the most important economic benefits brought about by distributed generation technologies to the distribution utility and the power system. Models are developed that allow the quantification of those benefits in economic terms. In some cases, industry regulators or utilities charge connection fees to the owners of distributed generators, even if they are saving the local utility considerable amounts of money every year in deferred network upgrades, reduced losses, avoided wholesale market purchases and others. Efficient economic systems dictate that a proper share of the indirect benefits created by a given economic activity leads to overall optimal independent decision-making by its participants. Quantifying and allocating the benefits of distributed generation to the owners improves the economic performance of their investments and encourages the implementation of those distributed generation applications most valuable to the system. View full abstract»

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  • Power System Risk Assessment Using a Hybrid Method of Fuzzy Set and Monte Carlo Simulation

    Publication Year: 2008 , Page(s): 336 - 343
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (242 KB) |  | HTML iconHTML  

    This paper presents fuzzy-probabilistic modeling techniques for system component outage parameters and load curves. The fuzzy membership functions of system component outage parameters are developed using statistical records, whereas the system load is modeled using a combined fuzzy and probabilistic representation. Based on the fuzzy-probabilistic models, a hybrid method of fuzzy set and Monte Carlo simulation for power system risk assessment is proposed to capture both randomness and fuzziness of loads and component outage parameters. An actual example using a regional system at the British Columbia Transmission Corpoation is given to demonstrate the application of the presented fuzzy-probabilistic models for system parameters and new system risk evaluation method. View full abstract»

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  • Economic Consequences of Alternative Solution Methods for Centralized Unit Commitment in Day-Ahead Electricity Markets

    Publication Year: 2008 , Page(s): 344 - 352
    Cited by:  Papers (25)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (558 KB) |  | HTML iconHTML  

    Many wholesale electricity markets call on the independent system operator (ISO) to determine day-ahead schedules for generators based on a centralized unit commitment. Up until recently, the Lagrangian relaxation (LR) algorithm was the only practical means of solving an ISO-scale unit commitment problem, and it was the solution technique used by most ISOs. Johnson et al. [1] demonstrate, however, that equity, incentive, and efficiency issues will arise from use of LR solutions, because different commitments that are similar in terms of total system costs can result in different surpluses to individual units. Recent advances in computing capabilities and optimization algorithms now make solution of the mixed-integer programming (MIP) formulation by means of branch and bound (B&B) tractable, often with optimality gaps smaller than those of LR algorithms, which has led some ISOs to adopt B&B algorithms and others proposing to do so. With the move towards B&B, one obvious question is whether the use of MIP will eliminate or reduce the issues with LR raised by Johnson et al. Using actual market data from an ISO, we demonstrate that both LR and MIP solutions will suffer the same equity issues, unless the ISO unit commitment problems can be solved to complete optimality within the allotted timeframe-which is beyond current computational capabilities. Our results further demonstrate that the size of the payoff deviations are not monotone in the size of the optimality gap, meaning smaller optimality gaps from B&B will not necessarily mitigate the issues Johnson et al. raise. We show that the use of "make-whole" payments, which ensure units recover any startup and no-load costs not recovered by inframarginal energy rents, can help to reduce surplus volatility and differences to some extent. View full abstract»

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  • The Measurement Outage Table and State Estimation

    Publication Year: 2008 , Page(s): 353 - 360
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (665 KB) |  | HTML iconHTML  

    State estimation uses measurements to obtain important power system operating information ("states"). This paper uses a tabular representation to quantify the effects of measurement failure (i.e., sensor failure or measurement communications failure). The concept of a measurement outage table is introduced to evaluate the state estimator performance under measurement failure conditions. The concept of a condition indicator is used and this includes a study of certain elements of the singular spectrum of the state estimator process matrix. Examples are shown to illustrate the concept. The analysis also shows that using condition indicators for measurement placement may improve the response of the state estimator under measurement failure conditions. View full abstract»

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  • Electricity Markets Cleared by Merit Order—Part I: Finding the Market Outcomes Supported by Pure Strategy Nash Equilibria

    Publication Year: 2008 , Page(s): 361 - 371
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (471 KB) |  | HTML iconHTML  

    In an electricity market cleared by a merit-order economic dispatch we first identify the necessary conditions for the market outcomes supported by pure strategy Nash equilibria (NE) to exist when generating companies (Gencos) game through their incremental cost offers or supply functions. A Genco may own any number of units, each offering to generate power through an incremental cost curve or supply function consisting of multiple blocks. Then, we develop a mixed-integer linear programming (MILP) scheme to find the NE without approximations or iterations. In Part II of this paper, we show how to use these NE to derive a dominant offer strategy in terms of gaming or not gaming that best meet the risk/benefit expectations of the participating Gencos. The MILP scheme is tested on several systems of up to 30 generating units, each with four incremental cost blocks. Finally, based on these results, we carry out a number of numerical analyses of how market power is influenced by the number and size of the competing Gencos. View full abstract»

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  • Electricity Markets Cleared by Merit Order—Part II: Strategic Offers and Market Power

    Publication Year: 2008 , Page(s): 372 - 379
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1770 KB) |  | HTML iconHTML  

    In an electricity market cleared by a merit-order economic dispatch we make use of the mixed-integer linear programming (MILP) scheme derived in Part I to find the market outcomes supported by a pure strategy Nash equilibria (NE). From these NE, we identify offer strategies in terms of gaming or not gaming that best meet the risk/benefit expectations of the participating Gencos. To do this, a number of measures of potential profit gain and loss are developed that quantify the notion of risk/benefit under the possible multiple NE. The NE identification scheme is tested on several systems of up to 30 generating units, each with four incremental cost blocks, also showing how market power is influenced by the number and size of the competing Gencos as well as by the imposed price cap. View full abstract»

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  • Continuous-Wavelet Transform for Fault Location in Distribution Power Networks: Definition of Mother Wavelets Inferred From Fault Originated Transients

    Publication Year: 2008 , Page(s): 380 - 388
    Cited by:  Papers (42)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (382 KB) |  | HTML iconHTML  

    The paper presents a fault location procedure for distribution networks based on the wavelet analysis of the fault-generated traveling waves. In particular, the proposed procedure implements the continuous wavelet analysis applied to the voltage waveforms recorded during the fault in correspondence of a network bus. In order to improve the wavelet analysis, an algorithm is proposed to build specific mother wavelets inferred from the fault-originated transient waveforms. The performance of the proposed algorithm are analyzed for the case of the IEEE 34-bus test distribution network and compared with those achieved by using the more traditional Morlet mother wavelet. View full abstract»

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  • When Supply Meets Demand: The Case of Hourly Spot Electricity Prices

    Publication Year: 2008 , Page(s): 389 - 398
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (355 KB) |  | HTML iconHTML  

    We use a supply-demand framework to model the hourly day-ahead price of electricity (the spot price) based on publicly available information. With the model we can forecast the level and probability of a spike in the spot price defined as the spot price above a certain threshold. Several European countries have recently started publishing day-ahead forecasts of the available supply. This paper shows this forecasted capacity is quite successful in predicting spot price movements 24 h ahead. View full abstract»

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  • Peak Load Management in Electrolytic Process Industries

    Publication Year: 2008 , Page(s): 399 - 405
    Cited by:  Papers (22)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB) |  | HTML iconHTML  

    Electrolytic process, employed for manufacturing basic chemicals like caustic soda and chlorine, is highly energy intensive. Due to escalating costs of fossil fuels and capacity addition, the electricity cost has been increasing for the last few decades. Electricity intensive industries find it very difficult to cope up with higher electricity charges particularly with time-of-use (TOU) tariffs implemented by the utilities with the objective of flattening the load curve. Load management programs focusing on reduced electricity use at the time of utility's peak demand, by strategic load shifting, is a viable option for industries to reduce their electricity cost. This paper presents an optimization model and formulation for load management for electrolytic process industries. The formulation utilizes mixed integer nonlinear programming (MINLP) technique for minimizing the electricity cost and reducing the peak demand, by rescheduling the loads, satisfying the industry constraints. The case study of a typical caustic-chlorine plant shows that a reduction of about 19% in the peak demand with a corresponding saving of about 3.9% in the electricity cost is possible with the optimal load scheduling under TOU tariff. View full abstract»

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  • Severe Multiple Contingency Screening in Electric Power Systems

    Publication Year: 2008 , Page(s): 406 - 417
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (554 KB) |  | HTML iconHTML  

    We propose a computationally efficient approach to detect severe multiple contingencies. We pose a contingency analysis problem using a nonlinear optimization framework, which enables us to detect the fewest possible transmission line outages resulting in a system failure of specified severity, and to identify the most severe system failure caused by removing a specified number of transmission lines from service. Illustrations using a three-bus system and the IEEE 30-bus system aim to exhibit the effectiveness of the proposed approach. View full abstract»

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  • Effects of Load Forecast Uncertainty on Bulk Electric System Reliability Evaluation

    Publication Year: 2008 , Page(s): 418 - 425
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (967 KB) |  | HTML iconHTML  

    Load forecast uncertainty is an important factor in long-range system planning and has been shown to have a significant impact on the calculated reliability indices in generating capacity studies. In general, a higher capacity reserve is required to satisfy a future uncertainty load than to serve a known load, at a specified level of reliability. Load forecast considerations are also important in composite generation and transmission system reliability studies, and their associated probability distributions. This paper examines the effects of load forecast uncertainty in bulk system reliability assessment incorporating changes in system composition, topology, load curtailment policies and bus load correlation levels. View full abstract»

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  • Power System “Economic Alarms”

    Publication Year: 2008 , Page(s): 426 - 433
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (693 KB) |  | HTML iconHTML  

    Power system alarms are used as advice to system operators relating to problematic operating conditions. In this paper, conventional alarms and alarm processing as well as the electrical signals that produce those alarms are revisited with a view of incorporating signals that relate to marketing of electrical energy (e.g., locational marginal prices, and forward market positions). The augmented alarms, termed "economic alarms" are intended to be public information, distributed to all power market players. The issues of divulging system information publicly are discussed. An illustrative example of the concept is presented. View full abstract»

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  • Computing Large-Scale System Eigenvalues Most Sensitive to Parameter Changes, With Applications to Power System Small-Signal Stability

    Publication Year: 2008 , Page(s): 434 - 442
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (325 KB) |  | HTML iconHTML  

    This paper describes a new algorithm, named the sensitive pole algorithm, for the automatic computation of the eigenvalues (poles) most sensitive to parameter changes in large-scale system matrices. The effectiveness and robustness of the algorithm in tracing root-locus plots is illustrated by numerical results from the small-signal stability analysis of realistic power system models. The algorithm can be used in many other fields of engineering that also study the impact of parametric changes to linear system models. View full abstract»

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  • Modeling Real-Time Balancing Power Market Prices Using Combined SARIMA and Markov Processes

    Publication Year: 2008 , Page(s): 443 - 450
    Cited by:  Papers (22)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (281 KB) |  | HTML iconHTML  

    This paper describes modeling of real-time balancing power market prices by using combined seasonal auto regressive integrated moving average (SARIMA) and discrete Markov processes. The combination of such processes allows generation of price series with periods where no demand for balancing power exists. The purpose of the model is simulation of prices to construct scenario trees representing possible realization of the stochastic prices. Such scenario trees can be used in planning models based on stochastic optimization to generate bid sequences to the balancing market. The spread of the prices in the tree and the shape of the scenarios are of central importance. Model parameter estimation methods reflecting the demands on scenario trees have therefore been used. The proposed model is also applied to data from the Nordic power market. The conclusion of this paper is that the developed model is appropriate for modeling real-time balancing power prices. View full abstract»

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  • An Optimal Pricing Scheme in Electricity Markets Considering Voltage Security Cost

    Publication Year: 2008 , Page(s): 451 - 459
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1143 KB) |  | HTML iconHTML  

    Optimal pricing in electricity markets has emerged as a multifunctional task for the grid managers as well as a major concern for the electricity providers and users. In this paper an optimal power flow problem is developed to take into account wider dimensions of the task by linking short-term and long-term performances of power systems via security pricing. The emphasis here is on the voltage stability phenomena as a security cost. The stochastic nature of power systems is taken into account to overcome the conservativeness associated with the severest single contingency approaches. This is done by inserting the approximated discrete processed risk data into the problem as a spline function to avoid lengthy iterative solutions. An effective combined offline and online procedure is then proposed to solve the optimization problem via the interior point method, preserving both the swiftness and precision of the solution. The effectiveness of the proposed problem definition and solution is confirmed through calculating locational marginal prices for a benchmark power system. View full abstract»

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  • Stochastic Joint Optimization of Wind Generation and Pumped-Storage Units in an Electricity Market

    Publication Year: 2008 , Page(s): 460 - 468
    Cited by:  Papers (114)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (807 KB) |  | HTML iconHTML  

    One of the main characteristics of wind power is the inherent variability and unpredictability of the generation source, even in the short-term. To cope with this drawback, hydro pumped-storage units have been proposed in the literature as a good complement to wind generation due to their ability to manage positive and negative energy imbalances over time. This paper investigates the combined optimization of a wind farm and a pumped-storage facility from the point of view of a generation company in a market environment. The optimization model is formulated as a two-stage stochastic programming problem with two random parameters: market prices and wind generation. The optimal bids for the day-ahead spot market are the ldquohere and nowrdquo decisions while the optimal operation of the facilities are the recourse variables. A joint configuration is modeled and compared with an uncoordinated operation. A realistic example case is presented where the developed models are tested with satisfactory results. View full abstract»

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Aims & Scope

Covers the requirements, planning, analysis, reliability, operation, and economics of electric generating, transmission, and distribution systems for general industrial, commercial, public, and domestic consumption.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Antonio J. Conejo
The Ohio State University