Showing papers in "IEEE Power & Energy Magazine in 1999"
TL;DR: In this article, a novel and sensitive frequency response analysis (FRA) technique for off/on-line condition monitoring of expensive power apparatus is presented. But the main objective is to investigate the applicability of this predictive maintenance technique to diagnosing power transformer failures, to characterize the transformer in a frequency plane for safe operation, and to develop on-line monitoring technique.
Abstract: This letter presents a novel and sensitive frequency response analysis (FRA) technique for off/on-line condition monitoring of expensive power apparatus. The main objective is to investigate the applicability of this predictive maintenance technique to diagnosing power transformer failures, to characterize the transformer in a frequency plane for safe operation, and to develop on-line monitoring technique. The effectiveness of this technique is demonstrated on a 2.5 MVA transformer housed at the High Voltage Laboratory of Pacific Power International (PPI) and then tested on three field transformers. The on-line technique is verified on a single-phase high voltage transformer. This study shows that FRA results are very sensitive to faults. The configuration of the measurement set up, frequency range and terminations play a greater role in getting reproducible, fault-indicating results. The interpretation of the voluminous data and analysis relevant to the faults opens a gateway to develop smart power apparatus.
66 citations
65 citations
TL;DR: In this article, a method for the analysis of the effectiveness of an SVC and a STATCOM of the same kVAr rating for first-swing stability enhancement is presented and the concept is demonstrated with a numerical example.
Abstract: A novel method for the analysis of the effectiveness of an SVC and a STATCOM of the same kVAr rating for first-swing stability enhancement is presented and the concept is demonstrated with a numerical example. The analysis shows that the STATCOM is superior to the SVC for first-swing stability enhancement.
53 citations
TL;DR: In this paper, two different approaches to estimate fault location are presented: spectrum estimation and wavelet analysis, which are tested and compared with simulations of typical transmission systems using the Electromagnetic Transients Program (EMTP).
Abstract: This letter suggests that a voltage recorder, placed next to a circuit breaker not as usual on the side of the substation, but on the side of the transmission line, may reveal the location of permanent faults. Two different approaches to estimating fault location are presented here: spectrum estimation and wavelet analysis. The methods are tested and compared with simulations of typical transmission systems using the Electromagnetic Transients Program (EMTP).
37 citations
TL;DR: In this paper, the changes of current frequency in R, L electric circuits supplied with 50 Hz sinusoidal voltage during changes of the phase angle between current and voltage are investigated.
Abstract: Investigations of the changes of current frequency in R, L electric circuits supplied with 50 Hz sinusoidal voltage during changes of the phase angle between current and voltage are presented. Changes of reactance of the electric circuit are demonstrated as consequences of change of current frequency during the transient process, which is a possible new explanation of the occurrence of the aperiodical component of the current. For fast transient processes of phase angle change, current frequency is different from the voltage frequency.
33 citations
TL;DR: In this article, an index equal to customer interruption costs divided by energy sales (CICs/kWh) overcomes the deficiency of standard reliability indexes such as SAIDI, which ignore the variation in interruption costs with customer type.
Abstract: Standard reliability indexes such as SAIDI ignore the variation in interruption costs with customer type. Thus, expenditure decisions driven by these indices that impact reliability, will not lead to the optimum improvement in value of service to customers. An index equal to customer interruption costs divided by energy sales (CICs/kWh) overcomes this deficiency. It is equally useful for identifying best-business-value solutions to power quality problems. It enables a supplier to decide which portfolio of projects (affecting power quality, or reliability, or neither) earns the highest return on investment, and allows a direct comparison of its value-creation record with that of its competitors.
27 citations
TL;DR: In this paper, the authors argue that a fixation on managing congestion, rather than curing it, and the spectre of market power within local generation markets, enabled by inadequate transmission, threaten to deprive the public of much of the benefit of electric power industry deregulation.
Abstract: The author argues that a fixation on managing congestion, rather than curing it, and the spectre of market power within local generation markets, enabled by inadequate transmission, threaten to deprive the public of much of the benefit of electric power industry deregulation.
26 citations
TL;DR: In this article, three-dimensional graphs of the Poynting vector distribution surrounding a three-phase line are presented to help engineering students understand the physical mechanism of electric energy transmission and its separation in active and nonactive components.
Abstract: This letter presents three-dimensional graphs of the Poynting vector distribution surrounding a three-phase line. Such displays help engineering students understand the physical mechanism of electric energy transmission and its separation in active and nonactive components.
23 citations
TL;DR: The preliminary results show that fuzzy logic can be used for accurate induction motors fault diagnosis if the input data are processed in an optimized way.
Abstract: This letter applies fuzzy logic to induction motors condition monitoring. The preliminary results show that fuzzy logic can be used for accurate induction motors fault diagnosis if the input data are processed in an optimized way.
22 citations
TL;DR: The suitability of applying AI techniques to PZ diagnosis will be established, and a review of existing applications of AI to PQ will be presented.
Abstract: lectric power quality (PQ has been a topic of consideration E for a few decades now, but power quality has acquired intensified interest and i m p o F c e during the last decade for many reasons. A major factor contributing to the importance of the quality of power is the deregulation of the power industry. Customers will demand higher levels of power quality to ensure the proper and continued operation of sensitive equipment and processes. Electric power quality problems are many and are largely dependent on the system configuration and the system equipment. The proper diagnosis of power quality problems requires a high level of engineering expertise, and the required expert knowledge is not in any one area, but is rather in many areas of power knowledge. Despite the existence of numerous capabilities for recording PQ waveforms, there is a great shortage of qualified power systems engineers who can analyze the data and diagnose/solve the problems. New powerful tools of interest to PQ diagnosis are those of artificial intelligence (AI). The use of artificial intelligence techniques in electric power has received extensive attention from many researchers. The AI tools of interest to the electric power community include expert systems (ES), artificial neural networks (ANN), fuzzy logic (FL), and the newer techniques of adaptive neuro-fuzzy systems (ANFS). These tools will be introduced and defined. The problems involved in performing PQ diagnosis will also be exposed. The suitability of applying AI techniques to PQ diagnosis will be established, and a review of existing applications of AI to PQ will be presented.
TL;DR: In this article, the distortion power D as a function of voltage and current harmonics of unlike frequencies is validated by measurements: one concludes that a proper interpretation of Budeanu's definition is correct and agrees with measured results.
Abstract: In a circuit where the load is nonlinear or the source has nonsinusoidal wave forms the apparent power is defined as S=/spl radic/(P/sup 2/+Q/sup 2/+D/sup 2/), where various formulations of distortion power D are reviewed. It is well known that the distortion power D is generated by the cross products of voltage and current harmonics of different frequencies. Accurate experiments are performed to measure the distortion power for a great variety of nonlinear load conditions of a 25 kVA transformer for a range of total harmonic current (THD/sub i/) and total harmonic voltage (THD/sub v/) distortions. The computed distortion power D as a function of voltage and current harmonics of unlike frequencies is validated by measurements: one concludes that a proper interpretation of Budeanu's definition is correct and agrees with measured results.
TL;DR: In this article, a new mathematical formulation for the vertical adjustments of analytically computed capacity factors is proposed. But this formulation is useful for estimating capacity factors at the time of planning and installation of new wind power stations and upgrading of existing wind stations by capacity addition.
Abstract: This letter discusses height extrapolation of capacity factors of a wind power plant. The power law is used to arrive at a new mathematical formulation for the vertical adjustments of analytically computed capacity factors. The Weibull statistical model, using cubic mean of wind speeds, is employed for estimating the capacity factors. The new formulation is useful for estimating capacity factors at the time of planning and installation of new wind power stations and upgrading of existing wind stations by capacity addition.
TL;DR: A real-time monitoring system that can be used to perform automated power quality testing is described, centered on a digital signal processor interfaced to a personal computer (PC).
Abstract: The purpose of this study is to develop and implement a power quality monitoring system that will enable power quality engineers to conduct diagnostic testing in the field. The study is limited to the implementation of hardware and software required to process the analog signals received. A real-time monitoring system that can be used to perform automated power quality testing is described. The system is centered on a digital signal processor (DSP) interfaced to a personal computer (PC). The test signal is input to the system through the A/D board. The signal is analyzed in real-time in the DSP, and the results are transferred to the PC through the communication interface. The PC presents the results and interacts with the user. This system can be used to perform onsite power quality studies.
TL;DR: The electricity supply industry in England and Wales (E&W) was restructured and privatized on Vesting Day, 31 March 1990 Eight years on, the UK government has reviewed the trading arrangements of the E&W electricity market and accepted the regulator's proposal of replacing the day-ahead market (the pool) by several forward markets, a short-term bilateral market, and a balancing market.
Abstract: The electricity supply industry in England and Wales (E&W) was restructured and privatized on Vesting Day, 31 March 1990 Eight years on, the UK government has reviewed the trading arrangements of the E&W electricity market and accepted the regulator's proposal of replacing the day-ahead market (the pool) by several forward markets, a short-term bilateral market, and a balancing market This letter looks at what some economists had examined of the present E&W electricity market under the day-ahead arrangement Such economic analysis may serve as a reference to power engineers elsewhere participating in the restructuring of their electricity supply industries
TL;DR: In this paper, the authors reviewed the existing standards for blackstart capability, standards for the restructured industry, and system blackstart under restructuring, and proposed a new set of standards.
Abstract: Restructuring the electric-power industry may present new challenges for bulk-power reliability. The incentives to maintain and properly deploy system blackstart services that worked for vertically integrated utilities may not work when the system operator, the transmission system, and individual generators are in separate commercial organizations. The four North American power system interconnections are designed to be in continuous synchronized operation. Individual pieces of equipment are taken out of service for maintenance, but each interconnection as a whole is designed to run without interruption. Nevertheless, the power system must be prepared for the rare occasions when all or a major portion of the system is forced out of service. The author reviews the existing standards for blackstart capability, standards for the restructured industry, and system blackstart under restructuring.
TL;DR: The wavelet transform is beginning to be used widely in power engineering and is especially suitable for feature enhancement of transients and thus makes it possible for power disturbances to be classified.
Abstract: The wavelet transform is beginning to be used widely in power engineering. Its effectiveness for analyzing transients with time localized information is now well known. Multiresolution analysis is especially suitable for feature enhancement of transients and thus makes it possible for power disturbances to be classified. In addition, the wavelet transform works well where the Fourier transform fails. A graphical insight is demonstrated in this letter.
TL;DR: In this paper, the spatial vector concept of the instantaneous apparent power is defined and some advantages obtained using these definitions in measuring power in a three-phase system and in vector control of electrical machines are discussed.
Abstract: The spatial vector concept of the instantaneous apparent power is defined. Some advantages obtained using these definitions in measuring power in a three-phase system and in vector control of electrical machines are discussed. Also, a physical interpretation of these definitions is given based on conventional electromagnetic theory.
TL;DR: An integrated congestion management procedure for a real-time operational environment is developed and market price response and coordination of dispatch by the independent system operator are incorporated into the proposed procedure to achieve an overall strategy.
Abstract: This letter discusses congestion management from an open access viewpoint and an integrated congestion management procedure for a real-time operational environment is developed. Market price response and coordination of dispatch by the independent system operator are incorporated into the proposed procedure to achieve an overall strategy.
TL;DR: The long-line model is used to determine the critical power that the line can transmit with and without series compensation, and shunt compensation at the load end of a long transmission line is determined.
Abstract: We determine the shunt compensation at the load end of a long transmission line to maintain the load voltage at a fixed percentage of the sending-end voltage. We use the long-line model to determine the critical power that the line can transmit with and without series compensation.
TL;DR: In this article, an analysis of oligopoly electricity markets, such as the British electricity spot market, is provided, where the main objective is to reveal how the behavior of suppliers affects each other's profit maximization.
Abstract: The aim of this letter is to provide an analysis of oligopoly electricity markets, such as the British electricity spot market. A model is developed under certain assumptions, first to describe the behavior of such a type of market. The main objective is to reveal how the behavior of suppliers affects each other's profit-maximization. The effectiveness of the proposed methodology is demonstrated on a test electricity industry that contains three different suppliers.
TL;DR: In this paper, a hybrid approach employing a neural network and the extended Ward-type equivalent method for fast online voltage security assessment of a large power system is presented, which results in an excellent external system response to contingencies in the internal system.
Abstract: This letter presents a hybrid approach employing a neural network and the extended Ward-type equivalent method for fast online voltage security assessment of a large power system. The boundary equivalent power injection can be matched quickly by using the proposed approach. Simulation results demonstrate that the new equivalent model results in an excellent external system response to contingencies in the internal system.
TL;DR: The features that make D SPs highly effective computational engines are studied and some applications requiring the high performance of DSPs are explored, including high-frequency converters and real time systems.
Abstract: The advent of programmable digital signal processors (DSPs) is creating a revolution in monitoring, control, and testing of motor drives. Their special architecture and high performance make it possible to implement a wide variety of nontrivial control and measurement algorithms at high sampling rates and reasonable cost. AC motor drives are typically a complex combination of linear, nonlinear, and switching elements. High-frequency converters add another dimension of complexity because of their fast dynamics. Real time systems, therefore, demand the use of high speed data-acquisition and control. DSPs meet the processing requirements imposed by such systems. In this letter, we study the features that make DSPs highly effective computational engines. We explore some applications requiring the high performance of DSPs. The issues involved in adopting a system architecture, selecting a DSP, and developing software for an application are discussed. The methodology described presents broad guidelines that can be intelligently applied to develop DSP-based solutions to meet specific requirements.
TL;DR: In this article, the authors argue that transmission is too important to be left to the government, or its ownership and control unnecessarily divided to the detriment of the public interest, and the best structural form for transmission in the United States is a separate, for-profit independent transmission company.
Abstract: The US transmission network, representing only 7% of electric bills, is vital to a competitive electricity market. The author argues that the network needs to be controlled by people and firms that are completely disinterested in generation market outcomes. Transmission also needs to be controlled by its owners, who will regard further investments in the grid to be strategic, i.e., conducive to their business. Transmission is too important to be left to the government, or its ownership and control unnecessarily divided to the detriment of the public interest. He believes that the best structural form for transmission in the United States is a separate, for-profit independent transmission company.
TL;DR: In a 1999 IEEE PES Winter Meeting panel session on ''Competitive Generation Agreements in Latin American Systems with Significant Hydro Generation'' as mentioned in this paper, the session was sponsored by the IEEE PE Energy Development and Power Generation Committee, and chaired by TJ. Hammons, chair of the International Practices for Energy Development, Power Generation, and Chair of the Power Engineering Chapter, UKRI Section; University of Glasgow, Scotland.
Abstract: This article is based on a 1999 IEEE PES Winter Meeting panel session on \"Competitive Generation Agreements in Latin American Systems with Significant Hydro Generation.\" The session was sponsored by the IEEE PES Energy Development and Power Generation Committee, and chaired by TJ. Hammons, chair of the International Practices for Energy Development and Power Generation, and chair of the Power Engineering Chapter, UKRI Section; University of Glasgow, Scotland.
TL;DR: In this article, the authors report that when the SWM problem is formulated as a mixed integer programming problem considering the constants of cost functions, start-up costs, and minimum production levels, the optimal prices can depart from marginal costs.
Abstract: In microeconomics, social welfare maximization (SWM) is formulated as a continuous problem, with the conclusion that marginal cost (MC) pricing is optimal in that it maximizes the total social welfare for consumers and producers. This is based on assumptions such as free entry/exit, no transaction costs, no externalities, etc. However, this paper reports that when the SWM problem is formulated as a mixed integer programming problem considering the constants of cost functions, start-up costs, and minimum production levels, the optimal prices can depart from marginal costs. The paper does not try to negate marginal cost pricing, but rather serves as a supplement to power economics.