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Focuses on the reliability and power quality at Champion International Corp. paper mill in Deferiet, New York. Numerous process interruptions experienced by Champion; Voltage sags emanating from the Niagara Mohawk Power Corp. transmission system; Causes and location of faults; Mitigation techniques.

Secondary or low-voltage (LV) networks are applied in many large cities throughout the U.S., and in some other countries. Various grounding schemes have been employed for the primary systems supplying these secondary networks. In this paper, characteristics of the different grounding schemes for the substation and primary feeders that supply the LV networks are reviewed. The impacts of primary system grounding on the ground fault currents, the unfaulted line-to-ground voltages, as well as the voltage sags in the LV network have been considered for the single line-to-ground fault on the primary. The differences between systems with network transformers having the delta- or grounded-wye-connected primary windings are discussed. The relationships between grounding characteristics and protection settings, including actual examples, have been documented. [ABSTRACT FROM AUTHOR]

This paper introduces an innovative concept for the use of multispectral stereo pair of satellite images to identify dangerous trees and plants along overhead transmission rights of way. Multispectral satellite images of the right of way are scanned automatically and the color (wavelength) of each pixel is analyzed. This scanning identifies healthy vegetation which may contain trees that endanger the line. Using multispectral stereo images, the height of each pixel is determined and the distance from the conductor is calculated. When this distance is less than the danger zone surrounding the conductors, the identified object or tree is assumed to endanger the line. Case studies using satellite images in the vicinity of Scottsdale, AZ and San Diego, CA demonstrate the feasibility of the proposed method. Details are given for prototype software development for satellite image scanning to determine tree interference with overhead transmission lines. [ABSTRACT FROM AUTHOR]

This paper focuses on the energy storage system and the power electronic interface included in microsources of the CERTS microgrid. CERTS stands for the Consortium for Electric Reliability Technology Solutions. The consortium was formed in 1999 to research, develop, and disseminate new methods, tools, and technologies to protect and enhance the reliability of the U.S. electric power system and efficiency of competitive electricity markets. To provide the plug-and-play feature and the power quality requirements of the CERTS microgrid, all microsources regardless of their prime mover type must have a unified dynamic performance. This necessitates attaching an energy storage module to some or all of the microsources. The storage module is attached to the prime mover through a power electronic interface that couples the microsource to the microgrid. Details of the energy storage module, the power electronic interface and the corresponding controls are described. Performance of an example microsource, which includes a synchronous generator, a storage module and an electronic interface, is studied. Dynamic performance of the example microsource when operating in the CERTS microgrid is evaluated based on digital time-domain simulations in the EMTP-RV software environment. Effectiveness of the storage module, the electronic interface and the corresponding controls in enhancing the microsource performance is verified. [ABSTRACT FROM AUTHOR]

Abstract-Partial discharges (PDs) generate wideband radio-frequency interference which can be used for noninvasive monitoring of discharges. This paper presents a novel method based on this principle for PD monitoring of substations. The significant advantage of this method lies in the ability to detect PD sources in energized equipment anywhere within a substation compound during normal operating conditions. The results obtained from the prototypes installed in the U.K. and U.S. substations are reported. Results include correlation with apparent charge and daily recordings obtained before, during, and after the failure of a 132-kV current transformer and 69-ky voltage transformer. [ABSTRACT FROM AUTHOR]

This paper demonstrates the results from a detailed study of the overvoltage protection of a particular 400/150-kV 400-MVA power transformer. The work presented here is based on a real-life power system substation design and data and initiated by Danish TSO Energinet.dk as a consequence of serious transformer overvoltag damage. A simulation model for the entire system consisting of overhead line, transformer, surge arrester, and earth grid has been created in PSCADIEMTDC. The main focus has been put on the earth grid, which has been submodeled in detail in MATLAB using an electromagnetic transient approach based on the thin-wire program made by J. H. Richmond for NASA in 1974. The earth grid model is verified with excellent agreement compared to already published results. The overvoltage performance of the particular case is analyzed, and it shows that the transformers LIWL have probably been exceeded. It is clearly illustrated that the transient performance of the earth grid plays an important role in the overall overvoltage protection system design. [ABSTRACT FROM AUTHOR]

This paper presents the validation of a numerical model based on the full-scale broken insulator tests on a 138-kV high-voltage steel transmission line. The University of Wisconsin and the Electric Power Research Institute performed these tests in 1978. A finite-element model of the line is developed to perform incremental nonlinear dynamic analysis, carried out in the time domain. Upon validation of the numerical model with the test results, a sensitivity study is carried out for various insulator lengths, ice thicknesses, and initial tensions to determine the effects of these parameters on the impact loads on the tower cross arm. Results of the study show that the impact loads are less sensitive to the change in insulator length but they do vary significantly when the ice loads and the initial tensions are increased. Studies of this type are now possible and are cost effective because of the use of commercial software not available at the time of the original research. [ABSTRACT FROM AUTHOR]

This paper develops statistical models for estimating the impacts of tree trimming on electric power system outages under normal (nonstorm) operating conditions. The models are based on an extensive data set from Duke Power, a company in the southeastern U.S., and the models used are a negative binomial generalized linear model and a Poisson generalized linear mixed model (GLMM). The results show that: 1) increasing tree trimming frequency does lead to a decrease in the number of outages on the electric power distribution system; 2) the effects of tree trimming on different circuits can be differentiated and measured; and 3) the Poisson GLMM provides a good fit to the data in this situation. In particular, the results of the model show that for the Duke Power system, one would have expected, on average, 0.9 fewer outages per circuit over the 43-month data recording period if the time between tree trimming cycles was decreased by 1 yr across the whole system. These models could be applied to other power systems, and the results should be useful for power managers in setting tree trimming frequencies and in focusing on the most frequent trimming efforts on those circuits for which trimming will have the greatest benefit. [ABSTRACT FROM AUTHOR]

This paper describes the identification of a common mold (i.e., fungus) growing on nonceramic insulators (NCIs) in service, and analyzes its impact on the electrical performance. The insulators evaluated were line posts removed from a 138-kV transmission line serving the interior (away from the coast) regions in Florida. The insulators had housings made from different types of silicone rubber (SR) and ethylene propylene rubber (EPR) polymer families. Electrical tests performed include surface resistance measurements and determination of contamination withstand capability (CWC) using the clean-fog procedure. Changes in the CWC were correlated to material changes by using micro-Fourier transform infrared (FTIR) analysis and surface resistance measurements. It was concluded that the mold growth is dependent on material formulation and outdoor environment. On SR insulators that exhibited mold growth, there was a reduction in the CWC when compared to the same insulator without the mold; however, even the reduced level of CWC was superior to that obtained on similarly rated EPR and porcelain insulators without any visible mold growth. Lastly, simple methods to remove the mold from the insulators are listed. [ABSTRACT FROM AUTHOR]