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Showing papers in "IEEE Power & Energy Magazine in 1986"


Journal ArticleDOI
TL;DR: In this article, a method for the online testing of a power system is proposed which is aimed at the detection of voltage instabilities, and an indicator L is defined which varies in the range between 0 (noload of system) and 1 (voltage collapse).
Abstract: A method for the online testing a power system is proposed which is aimed at the detection of voltage instabilities. Thereby an indicator L is defined which varies in the range between 0 (noload of system) and 1 (voltage collapse). Based on the basic concept of such an indicator various models are derived which allow to predict a voltage instability or the proximity of a collapse. The indicator uses information of a normal load flow. The advantage of the method lies in the simplicity of the numerical calculation and the expressiveness of the result.

1,012 citations


Journal ArticleDOI
TL;DR: An Industry Assessment Study (IAS) was conducted to evaluate the present reliability of powerhouse motors and to identify design and operational characteristics which, through advanced development, offer the potential of increased motor, and therefore, power plant reliability.
Abstract: An Industry Assessment Study (IAS) was conducted to evaluate the present reliability of powerhouse motors and to identify design and operational characteristics which, through advanced development, offer the potential of increased motor, and therefore, power plant reliability. The primary objective of the IAS was to collect, analyze, and interpret candid, detailed information concerning motor application, operating factors, installation, manufacturer, failures and causes of failures. The survey data covers 6312 motors from 168 generating units representing 65 utilities. This data covers 40 percent of the population surveyed. The large quantity of data allows a meaningful analysis when it is broken down into smaller groupings.

287 citations


Journal ArticleDOI
Chihiro Fukui1, Junzo Kawakami1
TL;DR: An expert system which can estimate possible fault sections using the information on operating protective relays and tripped circuit breakers and is written in Prolog.
Abstract: This paper deals with an expert system which can estimate possible fault sections using information from protective relays and circuit breakers. This system is applicable to dispatching centers and can help dispatchers to judge emergency situations as the first step in restoration procedures. When some faults occur, the system makes inferences based on both knowledge about protection systems and information on the operating protective relays and tripped circuit breakers. The system can give possible answers even in the case of multiple faults and false operations of relays and circuit breakers. This expert system is written in Prolog.

238 citations


Journal ArticleDOI
TL;DR: In this article, a general analysis to predict the steady state performance of an isolated self-excited induction generator feeding a balanced R-L load is presented, and the effect of machine core losses has also been considered.
Abstract: A general analysis to predict the steady state performance of an isolated self-excited induction generator feeding a balanced R-L load is presented. In the analysis the effect of machine core losses has also been considered. It is shown that besides voltage and frequency the analysis can be used to predict the minimum value of terminal capacitance required for excitation as well as for maintaining a constant terminal voltage. Comparison of the predicted and the experimental results shows a good agreement.

174 citations


Journal ArticleDOI
TL;DR: In this paper, a battery energy storage plant for load-frequency control and instantaneous reserve operation is presented, which is based on a test facility in Berlin (West) and the decision was made to build up a full-scale demonstration plant, which will be commissioned in early 1987.
Abstract: Energy storage plants utilizing batteries and thyristor power converters can be operated like pumped hydro storage units. Under the conditions actually prevailing in Europe, load leveling operation of such plants is not economical. Nevertheless, a battery energy storage plant promises both operational and economical advantages for load-frequency-control and instantaneous reserve operation. Queries according to this unconventional operation of batteries have been settled in a test facility in Berlin (West). After two years of test operation a decision was made to build up a full-scale demonstration plant, which will be commissioned in early 1987.

148 citations


Journal ArticleDOI
TL;DR: In this article, a comprehensive sensitivity analysis based on single and multiple point current injection techniques is conducted for uniform and two-layer soils, and the results show that the electric and magnetic fields can be used for detecting broken conductors.
Abstract: The fundamental concepts and analytical development related to electromagnetic fields generated by a network consisting of cylindrical conductors arbitrarily located in a conducting homogeneous soil are described and discussed. This method is applicable to overhead conductor networks as well. A comprehensive sensitivity analysis based on the single and multiple point current injection techniques is conducted. In particular, the surface electric and magnetic fields caused by an impressed current between the center point and the four corner points of a grounding network is examined. The analysis is conducted for uniform and two-layer soils. The results show that the electric and magnetic fields can be used for detecting broken conductors. It is also shown that the longitudinal currents, leakage currents, earth potentials, and magnetic fields are influenced by frequency, points of current injection, and configuration of the network.

141 citations


Journal ArticleDOI
TL;DR: In this article, the performance of a series, separately-excited, and shunt motors powered by a solar cell generator and loaded by two different types of loads, one a constant load and one a ventilator load, were analyzed with respect to the transient (starting) and steady state operation.
Abstract: The performance of dc motors (series, separately-excited, and shunt motors) powered by a solar cell generator and loaded by two different types of loads, one a constant load and one a ventilator load, were analyzed with respect to the transient (starting) and steady state operation. Direct current motors are employed in photovoltaic water pumping systems; therefore, the understanding of the system operation and the matching of the system components (solar cells, dc motor type, and load type) are important factors of the system design. Since the solar cell generator in a nonlinear and time-dependent power supply with an output that varies with the insolation (hourly and daily), the performance characteristics of the dc motor are different when supplied by a solar cell generator than when supplied by a conventional constant voltage source. The transient solution was obtained by using an available computer program - SUPER SCEPTRE. The separately - excited (or permanent magnet) motor with a ventilator load was found to be the most suitable for the solar cell generator. The series motor is quite acceptable, but the shunt motor gives poor performance. In all cases the ventilator load is more compatible with the solar cell generator than with the constant load.

139 citations


Journal ArticleDOI
TL;DR: An efficient branch-and-bound algorithm fully exploiting the knowledge of the problem is developed and it is shown that the method is reliable, efficient, and does not require separate testing of network observability.
Abstract: The problem of multiple bad data in state estimation is thoroughly analyzed and a new approach to bad data identification is proposed. The method supersedes the largest normalized residual method as a special case for single or multiple noninteracting bad data. The approach borrows the framework from Decision Theory. The bad data identification is formulated as a combinatorial optimization problem. The optimization takes into account the reliability of the measurements. An efficient branch-and-bound algorithm fully exploiting the knowledge of the problem is developed. The method is reliable, efficient, and does not require separate testing of network observability.

133 citations


Journal ArticleDOI
TL;DR: In this paper, a geometric interpretation of the normalized residuals test for single bad data is presented, and a method for detecting and identifying multiple bad data in electric power networks is developed.
Abstract: A method for detecting and identifying multiple bad data in electric power networks is developed by providing a geometric interpretation of the familiar normalized residuals test for single bad data. This generalized multiple bad data test amounts to determining whether the residual vector lies in a subspace determined by the suspect measurements and whether any portions of that subspace are orthogonal to the residual vector. These tests can be performed efficiently using appropriate projection matrices. Thne notion of critical measurement (removal renders the network unobservable) is extended to critical k-tuples of measurements to determine which bad data hypotheses are actually testable. For example, gross errors in critical measurements are not detectable, and gross errors in a critical pair of measurements are detectable but not identifiable. More generally, k-2 gross errors in a critical k-tuple of measurements are identifiable while k or k-l gross errors are detectable but not identifiable. In essence, the set of testable hypotheses is determined by the geometry of the space spanned by all possible residual vectors. A procedure for selecting and pruning a suspect set of measurements is described. Examples for the IEEE 14 bus network are provided.

111 citations


Journal ArticleDOI
TL;DR: In this paper, a method was developed which uses superposition of steady-state phasor solutions at the fundamental frequency and at the most important harmonic frequencies, with nonlinear inductances represented as harmonic current sources.
Abstract: Saturation effects in transformers and shunt reactors can produce harmonics in power systems. Their magnitude can sometimes be found with an electromagnetic transients program, by going from an approximate linear ac steady-state solution directly into a transient simulation in which the nonlinear effects are included. In lightly damped systems, such simulations can take a long time, however, before the distorted steady state is reached. Therefore, another method was developed which uses superposition of steady-state phasor solutions at the fundamental frequency and at the most important harmonic frequencies, with nonlinear inductances represented as harmonic current sources. This method can either be used by itself, or as an improved initialization procedure for electromagnetic transients programs.

104 citations


Journal ArticleDOI
TL;DR: In this article, the authors used the telegraph equations as a line model, voltage and current samples taken at one end of a line within the first 5 ms of fault inception are used to generate instantaneous voltage and currents profiles for the rest of the transmission line.
Abstract: The high frequency components in fault waveforms present undesirable effects to most fault location algorithms and as a consequence filtering of postfault signals, to remove the high frequency transients, is essential for accurate fault location. A fault location algorithm that derives from travelling wave principles can cope with high frequency transients since these basically depend on travelling wave phenomena. The development of such an algorithm is the objective of this paper. Using the telegraph equations as a line model, voltage and current samples taken at one end of a line within the first 5 ms of fault inception are used to generate instantaneous voltage and current profiles for the rest of the transmission line. The voltage and current estimation is based on the solution of the equations of the line model by the method of characteristics. Criteria functions involving any of the square of the voltage, the square of the current, or the product of the two are applied for determination of the fault position. Fault position is given by the peak variation in tangent to the above basic functions. The algorithm finds application in fault location on two and three-terminal networks at both transmission and distribution levels.

Journal ArticleDOI
TL;DR: In this article, the authors developed a methodology for the design of integrated renewable energy systems (IRES) which utilize different manifestations of solar energy to satisfy various energy needs in remote rural areas of developing countries by employing a linear programming approach.
Abstract: Integrated renewable energy systems (IRES) which utilize different manifestations of solar energy to satisfy various energy needs are well suited for the remote rural areas of developing countries By employing a linear programming approach, this paper develops a methodology for the design of IRES The method is quite general and it minimizes an objective function of total annual cost, subject to a set of energy and power constraints A numerical example is included to illustrate the design procedure

Journal ArticleDOI
TL;DR: In this paper, a detailed analysis of the phenomenon of cross-saturation is presented and it is shown that in a smooth-air-gap quadrature-phase machine this phenomenon is similar to the demagnetizing effect of crossmagnetizing armature reaction in a d.c.m. machine.
Abstract: A detailed analysis of the phenomenon of cross-saturation is presented and it is shown that in a smooth-air-gap quadrature-phase machine this phenomenon is similar to the phenomenon of the demagnetizing effect of cross-magnetizing armature reaction in a d.c. machine. In a quadrature-phase smooth-air-gap machine the resultant air-gap flux density distribution is decreased over one half of the pole-pitch and is increased under the other half of the pole-pitch and due to saturation the decrease is greater than the increase. Thus under saturated conditions, if the resultant m.m.f. distribution is displaced from the magnetic axes of the windings, a change in the quadrature-axis magnetizing current will cause a change of flux linkage in the direct-axis winding and vice versa, a change in the direct-axis magnetizing current will cause a change of flux linkage in the quadrature-axis winding. It is an important result that cross-saturation can also exist if the m.m.f. distributions are assumed to be sinusoidal. A physical derivation of the cross-saturation coupling factor is presented and a test is described which shows the existence of cross-saturation. A theoretical analysis of the experiment gives results which are in good agreement with the experimental results.

Journal ArticleDOI
TL;DR: In this article, a gate turn-off thyristor (GTO) converter is used to control reactive power in a superconducting magnet energy storage (SMES) in the wide range between lagging and leading phases.
Abstract: By using GTO's (Gate Turn-Off Thyristor) in place of ordinary thyristors in a conventional six pulse Greatz bridge converter, forced commutation is possible, so in the usage of ac-dc power conversion the reactive power of not only lagging but also leading phase can be absorbed. This feature enables superconducting magnet energy storage (SMES) to control reactive power in the wide range between lagging and leading phases. By virtue of this control ability , SMES will be applicable for a power system stabilyzer. A GTO converter which mainly consists of six GTO's was developed and tested. In this GTO converter, the energy stored in leakage inductances of the transformer is handled by voltage clipper circuit. Then, by using two sets of these GTO converters, we carried out some experiments of simultaneous active and reactive power control of SMES. The experiments on the developed control system were successfully performed and the ability of controlling reactive power in the wide range between lagging phase and leading phase was verified.


Journal ArticleDOI
TL;DR: In this paper, the fundamental concepts and analytical development related to the low frequency electromagnetic fields generated by a single current-carrying conductor immersed in a medium of infinite extent and in a conducting half-space are described and discussed.
Abstract: The fundamental concepts and analytical development related to the low frequency electromagnetic fields generated by a single current-carrying conductor immersed in a medium of infinite extent and in a conducting half-space are described and discussed. It is shown that vertical conductors buried in earth are not detectable by above earth surface measurements of magnetic fields. Examples and numerical results involving energization of typical intact and broken single conductors are then described and commented on. It is shown that earth surface potentials and above earth magnetic fields are significantly distorted by a break in horizontal and oblique conductors. Finally, experimental measurements on a model with considerable heterogeneities confirm the significant influence of conductor discontinuities on the potential and magnetic field profiles.

Journal ArticleDOI
TL;DR: In this paper, the authors discuss observations of induced voltages on the experimental overhead distribution line at a power plant facing the Japan Sea from October 1984 through March 1988, and the induced voltage waveforms generated on a distribution line were calculated by means of improved numerical analysis which took the height of the stack into consideration.
Abstract: The authors discuss observations of induced voltages on the experimental overhead distribution line at a power plant facing the Japan Sea from October 1984 through March 1988. Waveforms of induced voltage from lightning strokes to a high stack of the power plant were measured simultaneously with the current waveforms of the lightning stroke to the stack. The polarity of lightning-induced voltage is opposite to that of lightning stroke current, regardless of the season. Except for unusual conditions, lightning induced voltages have a unipolar waveform. The lightning-induced voltage on the closest point of a distribution line to the lightning striking point is the maximum. The induced voltage waveforms generated on a distribution line were calculated by means of improved numerical analysis which took the height of the stack into consideration. The calculated results agree better with the measured waveforms than made those made by means of an earlier analysis method. It is clarified that bipolar induced voltages are not produced by usual lightning stroke currents. >

Journal ArticleDOI
TL;DR: In this article, the average values for the exponents of a weighted harmonic factor are derived for transformers, induction and universal machines as they occur in electrical appliances, based on a theoretical loss analysis and on experimentally obtained temperature data.
Abstract: Average values for the exponents of a weighted harmonic factor are derived for transformers, induction and universal machines as they occur in electrical appliances. The derivation is based on a theoretical loss analysis and on experimentally obtained temperature data [1,2]. The influence of the temperature on the lifetime of the above electromagnetic devices is discussed. An attempt has been made to recommend a limit for the value of the weighted harmonic factor which indirectly limits the sum of the weighted amplitudes of occurring voltage harmonics in a distribution system. Thus a criterion has been devised which judges harmonic voltage spectra based on the temperature increase they produce in an electromagnetic apparatus. As an example, two possible sets of voltage harmonic spectra are discussed that would protect consumers, as well as utility systems, from adverse effects. The work described has been supported by the U.S. Department of Energy.

Journal ArticleDOI
M. Kanoe1, G. Takahashi1, Tadashi Sato1, M. Higaki1, Mori Etsunori1, Kiyoshi Okumura1 
TL;DR: In this article, an optical voltage and current measuring system based on the electrooptic effect in bismuth germanium oxide Bi4Ge3O12 and magneto-optic effects of borosilicate crown glass for the purpose of utilization in electric power systems was developed.
Abstract: Recently, optical voltage and current measuring methods based on a principle different from that of the existing apparatus have been developed. As the most promising method among them, a voltage measuring method which uses an electrooptic effect called the Pockels effect and a current measuring method which uses a magnetooptic effect called the Faraday effect have been proposed. The authors have developed an optical voltage measuring system based on the electrooptic effect in bismuth germanium oxide Bi4Ge3O12 and a current measuring system based on the magnetooptic effect of borosilicate crown glass for the purpose of utilization in electric power systems. As a result of the development, high accurate voltage and current measuring systems such as non linearity error less than ±0.4% and temperature stability less than ±1.0% were obtained. Furthermore, short-circuit current was measured with the current measuring system, and an accuracy within 0 to -4% in the range of 30 kApeak to 150 kApeak was obtained. When the measuring systems were mounted on the model of 70 kV class gas insulated switchgears, it was verified that the measuring systems had satisfactory linearity and temperature stability.

Journal ArticleDOI
TL;DR: Bohn was Eximbank's first vice president and vice chairman, U.S. Ambassador and executive director of the Asian Development Bank, and special assistant to the Secretary of the Treasury as mentioned in this paper.
Abstract: Bohn was Eximbank's first vice president and vice chairman, U.S. Ambassador and executive director of the Asian Devel¬ opment Bank, and special assistant to the Secretary of the Treasury. From 1967 until 1981, Bohn served as division manager for North America and vice president, correspon¬ dent banking at Wells Fargo Bank in San Francisco. Earlier, he was manager of the bank's International Group in Los An¬ geles and spent four-and-one-half years in Tokyo as vice president and Far East representative.

Journal ArticleDOI
TL;DR: In this paper, a method for determining the costeffectiveness of wind energy and the economic limitations of penetration into electrical power systems is presented based on a Monte-Carlo approach which simulates the hour-byhour operation of the power system.
Abstract: A method for determining the costeffectiveness of wind energy and the economic limitations of penetration into electrical power systems is presented. It is based on a Monte-Carlo approach which simulates the hour-by-hour operation of the power system. The hourly random variations in wind and load are modeled in addition to the operating constraints inherent in conventional generation. The economic assessment is based on a selected one-year simulation period, Two examples of the application of this method are given.

Journal ArticleDOI
TL;DR: In this paper, the steady-state performance of the variable speed constant frequency double output induction generator (VSCF-DOIG) is investigated, where the generator is subjected to a strict control strategy in which the stator current is kept constant and equal to its rated value.
Abstract: The steady-state performance of the variable speed constant frequency double output induction generator (VSCF-DOIG) is investigated. The generator is subjected to a strict control strategy in which the stator current is kept constant and equal to its rated value. This allows the generator to deliver rated power from its stator terminals, while from its rotor terminals a variable power output is obtained that is proportional to its rotor speed. Thus more than rated power can be extracted from the induction machine without overheating. The theoretical results of this investigation are verified experimentally.

Journal ArticleDOI
TL;DR: A brief survey of the application of the magnetic equivalent circuit method in evaluation of steady and transient states in induction machines is described in this paper, taking into account machine geometry, type of windings, rotor skewing, magnetizing curve etc., this method is able to solve transients in ac machines.
Abstract: A brief survey of the application of the magnetic equivalent circuit method in evaluation of steady and transient states in induction machines is described in this paper. Taking into account machine geometry, type of windings, rotor skewing, magnetizing curve etc., this method is able to solve transients in ac machines. Sample calculations are provided, showing the influence of the number of stator and rotor slots, initial conditions, rotor skewing and saturation on electromagnetic and mechanical values during transients.

Journal ArticleDOI
TL;DR: In this article, a methodology to predict the performance of photovoltic generator based on long-term climatological data and expected cell performance is described, which is used to calculate the probability distribution function parameters for each hour of a typical day of any season, week or day.
Abstract: This paper describes a methodology to predict the performance of photovoltic (PV) generator based on long term climatological data and expected cell performance. The methodology uses long term historical data on insolation to calculate the probability distribution function parameters for each hour of a typical day of any season, week or day. Once the probability distribution function parameters are calculated, they are used to evaluate the predicted hourly, daily, weekly and seasonal capacity factors of a particular design of a PV panel/array at a particular site. Long term insolation data from Sterling, Virginia have been utilized with Solarex SX-110 panel designs to predict PV array performance.

Journal ArticleDOI
TL;DR: A new travelling wave digital protection scheme to be used as an ultra high speed (UHS) EHV/ UHV transmission line relay is presented and achieves significantly improved security and dependability.
Abstract: A new travelling wave digital protection scheme to be used as an ultra high speed (UHS) EHV/ UHV transmission line relay is presented in this paper. Some of the potential problems and limitations associated with other travelling wave schemes are avoided. Verification of the relay operating principles is presented through digital computer numerical simulation using an electromagnetic transients program (EMTP) in conjunction with simulation of the proposed algorithm. Parallel digital processing is incorporated through multi-microprocessor implementation. Hardware and software of a multiprocessor prototype are managed in a way to fit the algorithm requirements in as simple a construction as possible. The resulting scheme achieves significantly improved security and dependability, in addition to the main features: fault classification and UHS phase selection in selective-pole schemes with minimum communication between the protected ends.

Journal ArticleDOI
Satoru Yanabu1, Y. Satoh1, T. Tamagawa1, E. Kaneko1, S. Sohma1 
TL;DR: In this article, an axial magnetic field electrode was developed for vacuum circuit breakers, through various improvements in its structure, this electrode has been refined for practical application in vacuum circuit breaker interrupters.
Abstract: About ten years ago, an axial magnetic field electrode was developed for vacuum circuit breakers. Since then, through various improvements in its structure, this electrode has been refined for practical application in vacuum circuit breaker interrupters. The application has successfully covered not only medium-voltage circuit breakers, but also high-voltage (84kV), dc current and large-current circuit breakers. In this paper, our ten years' experience in this area are described.

Journal ArticleDOI
TL;DR: Large scale simulation results, including use of relay outputs for discrete supplemental control action; additional details on design and testing of the microprocessor based relay; and experience during an extensive monitoring period at Malin Substation on the Pacific AC Intertie.
Abstract: A new out-of-step relaying concept has been previously reported. The concept involves augmaenting apparent resistance (R) measurement with rate-of-change of apparent resistance (Rdot) computation. The new R-Rdot relay thus has more intelligence for control decisions. This follow-up paper presents the following new information: large scale simulation results, including use of relay outputs for discrete supplemental control action; additional details on design and testing of the microprocessor based relay; and experience during an extensive monitoring period at Malin Substation on the Pacific AC Intertie. The relay is now energized for initiating controlled separations at several locations within the Western North American Power System.

Journal ArticleDOI
TL;DR: An Artificial Intelligence (AI) based, on-line Turbine Generator diagnostic expert system which is is presently under development is described, using the inputs from a number of sensors to evaluate the condition of the equipment and communicate appropriate action.
Abstract: An Artificial Intelligence (AI) based, on-line Turbine Generator diagnostic expert system which is is presently under development is described. Utilizing the inputs from a number of sensors, the diagnostic system evaluates the condition of the equipment and communicates appropriate action. This is an improvement over present monitoring systems which simply apply alarm limits to the value of each sensed variable. In comparison to a monitoring system, a diagnostic system identifies equipment and instrument problems earlier with a higher degree of accuracy.

Journal ArticleDOI
TL;DR: In this article, a 3n analytical approach is presented to evaluate the probability distributions associated with the reliability indices of electric distribution systems with radial configurations and the results of a study on sample configuration are presented in this paper.
Abstract: Reliability indices of an electric distribution system are functions of factors such as component failures, repairs and restoration times which are random by nature. These indicies are, therefore, random variables and can be described by probability distributions. The mean values of the probability distributions associated with the reliability indices are very useful and conventional reliability analysis is normally only concerned with these values. There is, however, an increased awareness of the need to evaluate parameters which give information regarding the variation of the indices around their mean values. This paper presents 3n analytical approach to evaluate the probability distributions associated with the reliability indices of electric distribution systems with radial configurations. The results of a study on sample configuration are presented in this paper.

Journal ArticleDOI
TL;DR: A magnetic direction-finding network for the detection of lightning cloud-to-ground strikes has been installed along the east coast of the United States as mentioned in this paper, where most of the lightning occurring from Maine to Florida and as far west as Ohio is detected.
Abstract: A magnetic direction-finding network for the detection of lightning cloud-to-ground strikes has been installed along the east coast of the United States. Most of the lightning occurring from Maine to Florida and as far west as Ohio is detected. Time, location, flash polarity, stroke count, and peak signal amplitude are recorded in real time. Flash locations, time, and polarity are displayed routinely for research and operational purposes. Flash density maps have been generated for the summers of 1983 and 1984, when the network only extended to North Carolina, and show density maxima in northern Virginia and Maryland. Computer-based display systems that access this network in real time are now in use to evaluate the usefulness of the data.