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This paper presents a diakoptic-based distributed state estimation (SE) algorithm suitable for large-scale power systems. In the proposed approach the large-scale power system is divided into a certain number of subsystems by removing tie line measurements. Based on diakoptic theory, the SE problem is then partitioned into a number of subproblems which are solved for each subsystem using local computational resources. In subsequent steps, the intermediate subsystem SE solutions are sent to a central computer for completing the state estimation process by taking the tie line measurements into consideration. Phasor measurement units are used to make each subproblem solvable and to coordinate the voltage angles of each subsystem SE solution. Test results on the IEEE 14-bus test bed and IEEE 118-bus test bed are provided. Index Terms--Diakoptics, distributed state estimation, measurement tearing, phasor measurement units, state estimation.

Although there are still uncertainties regarding the extent to which climate change may be occurring, some approximations and reasonable assumptions can be made relating to daily high and low temperatures. Further, urbanization may impact ambient temperature. These temperature models may be used with standardized methods to estimate the loss of life of oil-immersed power distribution transformers. In this way, the impact of increased ambient temperatures on distribution transformer loss of life may be preliminarily assessed. Results of standardized engineering studies for illustrative cases are shown in this paper. Index Terms--Ambient temperature, climate change, distribution engineering, distribution transformers, loss of life, urbanization, IEEE standard C57.91.

With the creation of balancing authorities by the North American Reliability Council that span large portions of the North American interconnection, and stringent requirements for real time monitoring of power system evolution, faster and more accurate state estimation algorithms that can efficiently handle systems of very large sizes are needed in the present environment. This paper presents a distributed state estimation algorithm suitable for large-scale power systems. Synchronized phasor measurements are applied to aggregate the voltage phase angles of each decomposed subsystem in the distributed state estimation solution. The aggregated state estimation solution is obtained from the distributed solution using a sensitivity analysis based update at chosen boundary buses. Placement of synchronized phasor measurements in the decomposed subsystems is also investigated in this paper. Test results on the IEEE 118-bus test bed are provided. Index Terms--Distributed state estimation, phasor measurement units, state estimation, synchronized phasor measurements.

This paper demonstrates the use of a slow-coherency-based generator grouping algorithm and a graph theoretic approach to form controlled islands as a last resort to prevent cascading outages following large disturbances. The proposed technique is applied to a 30 000-bus, 5000-generator, 2004 summer peak load, Eastern Interconnection data and demonstrated on the August 14, 2003 blackout scenario. Adaptive rate of frequency decline-based load shedding schemes are used in the load rich islands to control frequency. The simulation results presented show the advantage of the proposed method in containing the impact of the disturbance within the islands formed and in preventing the impact of the disturbance from propagating to the rest of the system. This is demonstrated by the significant reduction in line flows in the rest of the system and by improved voltage and relative angle characteristics. Based on the suggestion in the joint U.S.-Canadian task force final report on the blackout, load shedding without any islanding is also performed, and results obtained are compared with the proposed controlled islanding method. The islanding method outperforms the load shedding-only method in reducing the transmission line flows, but both methods have similar effects on voltage and relative angle behavior. Index Terms--Blackout prevention, islanding, load shedding, power system stability, slow coherency.

Controlled islanding refers to the controlled separation of an interconnected power system into electrically isolated regions. The objective of this paper is to develop adaptive controlled islanding as a component of an emergency power system control strategy. There are two primary aspects of controlled islanding: 1) where to island and 2) when to island? Assisted by a decision tree (DT) approach, this paper seeks to address the 'when to island' aspect. A decision tree based tool is proposed to recognize conditions existing in the system that warrant controlled islanding. A 29-generator, 179-bus system is employed to demonstrate the tool. Simulation data are used to train DTs, and the online performance of DTs is then evaluated as part of a controlled islanding strategy. Index Terms--Controlled islanding, decision tree, machine learning, power system stability, R-Rdot relay, self healing, special protection systems.

Slow coherency-based generator grouping in power systems is primarily dependent on the participation of generators in the slow modes. In the literature, generator coherency has been typically obtained at a specific operating point. This paper presents a new approach using the continuation method to trace the loci of the coherency indices of the slow modes in the system with respect to variation in system conditions to obtain the updated coherency information between generators. The approach has been applied to a 10-generator 39-bus New England system, and a 29-generator 179-bus model of the WECC system and the impact of load variation on generator coherency indices has been investigated. Index Terms--Continuation method, generator coherency indices tracing, power system dynamics, slow coherency based grouping.

This paper presents a method to identify synchronous generator parameters from on-line data measured at the terminals of the machine. An observer for estimation of synchronous generator damper currents is designed and implemented. The observer-estimator is used in a Graphic User Interface (GUI) application. Possible internal machine fault conditions can be detected and remedial action can be applied. Noise filtering and bad data detection and rejection are implemented to increase the reliability of the estimates. Saturation of the synchronous generator inductances is also considered. Secondary objectives include calculation of the error characteristics of the estimation, development of an index of confidence, study of the observability of generator parameters, and evaluation of alternative GUI features. Index Terms--Damper currents, filtering, graphic user interface, modeling, observer, on-line measurements, parameter estimation, pseudoinverse, saturation, state estimation, synchronous generator, visualization.

This paper provides a summary of the state of electric power engineering education through descriptions of professional society activities, Internet resources, and results of a worldwide survey conducted in March 2003. Index Terms--Engineering education, Internet resources.

This paper contains an analog to the Fourier series (FS) based on the cosine-and-sine function cas(center dot). The new series is related to the Hartley transform, and therefore, it is termed the Hartley series (HS). Properties and applications of the Hartley series are discussed in general. The technique is valuable for the assessment of power quality in industrial and commercial power distribution systems. In particular, the impact of switched and pulse modulated loads and ac/dc converters may be analyzed. The paper also contains an example in which an industrial distribution system impacted by a six-pulse rectifier load is analyzed.

The current status of parallel processing as used in electric power systems analysis is presented. The use of parallel processing is induced by the need for rapid solution in power system problems. For a specific problem, a separate derivation has to be made that could be used as a parallel algorithm. The answer has to done in a parallel machine with compatible architecture and algorithms. The last decade has seen research done on algorithm development and the evaluation of multiprocessor architectures has just began. Hardware development still has no definite path with existing machines suitable only for research work.

This letter contains the analysis of the increase of fault current due to the installation of distributed resources or merchant plants. An index called the average change of fault (ACF) current is proposed. The ACF can be applied to indicate the contribution of the increase of fault current and to allocate the responsibility of system upgrades among the owners of distributed resources. Index Terms--Dispersed generation, distributed resources, fault current calculation, power distribution.

This paper reports on new efforts in the modernization of the basic undergraduate courses and a graduate curriculum in electric power engineering. The main focus of the paper is the modernization of the way power engineering is portrayed to students. The motivation is the recognition of the new deregulated and restructured environment in power engineering and the broadening of the area in general. At the undergraduate level, a multimedia approach is described in which renovation of the curriculum is done in such a way as to allow broadening of the subject material. At the graduate level, new efforts in power electronics and electric power quality are described. The implementations of changes as those reported here were made at several universities including Arizona State University. Index Terms--Education, energy conversion, power electronics.

This letter explains the duality between the generation unit commitment problem and the distribution restoration problem. The importance of this observation is that extensive analysis and prototyping of efficient solutions to the unit commitment problem can be applied to the distribution restoration problem. Index Terms--Distribution engineering, distribution restoration, duality, unit commitment.

This letter describes electric power quality as an important component of electric power engineering education. Because power quality engineering relies on signal processing concepts as well as applied power engineering, students in both undergraduate and graduate educational programs find the topics cross-disciplinary, practical, and motivational. Index Terms--Power distribution, power engineering education, power quality.

In this letter, modification to an existing formula for determining the contribution of generation companies to unscheduled flows in electric power networks is presented. The enhanced form of the contribution factor formula provides two options for calculating the contribution of generation companies based on the magnitudes of all the minor loop flows and the largest minor loop flow induced, respectively. A numerical example for a modified IEEE 30-bus test system is provided. Index Terms--Contribution factors, loop flow, unscheduled flow, vector norm.

A manpower shortage is forecasted for qualified electric power engineers as the number of retirees exceeds new hires. This letter discusses the opportunities and challenges of the distant e-learning (e-training) for electric power engineers and presents the progress of two programs established in North America. The experience is augmented by observations from a sampling at other universities. E-learning is suggested as a measure for enhancing power engineering professional training. Index Terms--Continuing education, e-learning, power engineering education.

Controlled islanding is a special protection strategy aimed at preventing a system-wide blackout as a result of the cascading of low probability events. This letter addresses the main issues and proposes a conceptual framework for a centralized and proactive controlled islanding strategy. Index Terms--Controlled islanding, out-of-step relay, power system stability, R-Rdot relay, special protection system.

The least-squares method has been used extensively for state estimation in electric power engineering. However, this method is not always suitable when the process matrix is characterized by structural defects. This letter demonstrates the Huber function technique in a power engineering application. This technique is a slight departure from the leastsquares method and downweighs large residuals. A statistical test to identify possible structural imperfections in the model is introduced. Index Terms--Huber, least squares, multicollinearity, rank, robust estimation, state estimation, synchronous generators.