Electric Power Utilities Research Articles

A DSS Design Model for complex problems: Lessons from mission critical infrastructure

This paper presents a new DSS Design Model for complex, mission critical decision-making situations and its technical, conceptual, and partial empirical evaluation. The new model was derived from conceptual design research and through a deep qualitative field research study at an electric power utility control center—a typical arena for “wicked” problems. The model suggests an iterative process of theory, simulation, and decision-making interactions. The DSS Design Model is validated using a tool instantiation, microgrid mini-case, and current research of a KMDSS for telecommunications. Main findings suggest that broader and more integrated approaches are necessary to design DSS for complex domains.

High Thermoelectric Figure of Merit and Nanostructuring in Bulk p‐type Na1−xPbmSbyTem+2

Thermoelectric materials are special types of semiconductors that function as “heat pumps” and as heat-to-electricity converters. Thermoelectric power generation allows for small size, high reliability, and quiet operation. Efficient thermoelectric-based heat-to-electricity converters require higher performance materials than are currently available. Direct conversion of heat to electricity could be achieved with solidstate devices based on thermoelectric materials. These devices could play an important role in future energy production, conversion, management, and utilization. When a temperature gradient is created across a thermoelectric module, a voltage is generated, owing to the Seebeck effect. This voltage can be used to drive an external load. Currently, there is a strong scientific and technological drive to identify new materials with enhanced thermoelectric figures of merit ZT= (sS/k)T (where s is the electrical conductivity, S the thermopower or Seebeck coefficient, k the thermal conductivity, and T the temperature). The numerator sS is called the power factor PF. Several classes of materials are currently under investigation, including complex chalcogenides, doped PbTe and its solid solutions, such as Pb1 xSnxTe, [5,6] superlattice thin films, and quantum-dot superlattices. Also of interest are skutterudites, metal oxides, and intermetallic clathrates. The superlattice thin-film structures of Bi2Te3/Sb2Te3 grown from chemical vapor deposition, and of PbSe0.98Te0.02/PbTe formed by molecular beam epitaxy (MBE) have figures of merit greater than ZT= 2 (at approximately 300 and 550 K, respectively). The MBE-grown thin films PbSe0.98Te0.02/PbTe are n-type materials and contain pyramid-shaped “nanodots” of PbSe of uniform size (approximately 20 nm), which form spontaneously inside a matrix of PbTe. Because energyconversion applications require materials in large quantities, we seek bulk analogues of these systems with similar figures of merit. A recent contribution to these efforts was the discovery of the n-type Ag-based tellurides AgSbTe2/PbTe, which can exhibit high figures of merit (ZT 1.7 at 700 K) when properly doped. To construct a fully functioning optimal thermoelectric device, both nand p-type materials are needed. To date, there is no p-type counterpart to AgSbTe2/ PbTe with similar performance. The highest figure of merit reported for p-type bulk materials (ZT 1.2 at 700 K) is exhibited by the so-called TAGS system (based on Te, Ag, Ge, and Sb: (GeTe)1 x((Ag2Te)1 y(Sb2Te3)y)x). [23] These Ge-containing materials, though more efficient than PbTe, have found limited use, owing to their high cost and to a lowtemperature phase transition. Recently, we described the ptype materials Ag(Pb1 ySny)mSbTe2+m, which show outstanding thermoelectric properties, reaching a maximum figure of merit of ZT 1.45 at 630 K. Herein, we report that the Ag-free system Na1 xPbmSbyTem+2, with appropriate combinations of m, y, and x, achieves record-high ZT values for a p-type bulk thermoelectric material. The effect of the composition on the thermoelectric properties is profound. We show that the high performance of these materials derives mainly from a low thermal conductivity. High-resolution transmission electron microscopy (HRTEM) demonstrates pervasive nanostructuring in Na1 xPbmSbyTem+2, which may be the root cause for the remarkably low thermal conductivity. The Na1 xPbmSbyTem+2 system was selected for study because it should be naturally prone to create Na,Sb-rich clusters in the lattice. The distribution of Na and Sb ions in the Pb sublattice cannot be random, as would be demanded by a solid solution, because Coulombic forces alone tend to drive the system to clustering at the nanoscale, thereby lowering the overall energy. The results described herein are in agreement with long-standing theoretical predictions that nanostructuring in semiconductors would lead to enhanced thermoelectric figures of merit. The Na1 xPbmSbyTem+2 materials could find applications in devices for power generation from a wide variety of hot sources, for example, vehicle exhausts, coal-burning installations, or electric power utilities. Na1 xPbmSbyTem+2 (y 1) samples (see Supporting Information for synthesis details) exhibit p-type conduction from 300 to 700 K. Ingots with the composition Na0.95Pb19SbTe21 (m= 19, x= 0.05, y= 1) exhibit an electrical conductivity of s= 1422 Scm 1 with a positive thermopower of S= 105 mVK 1 at room temperature. This leads to the relatively high power factor of PF= 15.6 mWcm K . The temperature dependence of the electrical conductivity and the thermopower of Na0.95Pb19SbTe21 are shown in Figure 1A. The conductivity decreases with increasing temperature, which is consistent with degenerate semiconductors, and reaches s= 150 Scm 1 at 700 K. However, the thermopower increases rapidly to S= 357.6 mVK 1 at 700 K, yielding a much higher power factor of PF= 19 mWcm K . For samples of composition Na0.95Pb20SbTe22 (m= 20, x= 0.05, y= 1), an electrical conductivity of s= 1541 Scm 1 and a [*] Dr. P. F. P. Poudeu, Prof. M. G. Kanatzidis Department of Chemistry Michigan State University East Lansing, MI 48824 (USA) Fax: (+1)517-353-1793 E-mail: kanatzid@cem.msu.edu

Application of artificial neural network methods for the lightning performance evaluation of Hellenic high voltage transmission lines

Feed-forward (FF) artificial neural networks (ANN) and radial basis function (RBF) ANN methods were addressed for evaluating the lightning performance of high voltage transmission lines. Several structures, learning algorithms and transfer functions were tested in order to produce a model with the best generalizing ability. Actual input and output data, collected from operating Hellenic high voltage transmission lines, as well as simulated output data were used in the training, validation and testing process. The aims of the paper are to describe in detail and compare the proposed FF and RBF ANN models, to state their advantages and disadvantages and to present results obtained by their application on operating Hellenic transmission lines of 150 kV and 400 kV. The ANN results are also compared with results obtained using conventional methods and real records of outage rate showing a quite satisfactory agreement. The proposed ANN methods can be used by electric power utilities as useful tools for the design of electric power systems, alternative to the conventional analytical methods.

Wood cross-arms coated with polyurethane resin - tests and numerical simulations

Brazil's electric power utilities have commonly employed native timbers as the main material for manufacturing cross-arms for distribution lines. However, the increasingly high costs of these timbers and Brazil's new environmental laws have contributed to change this situation, spurring research on new materials for application in transmission and distribution systems. This paper discusses two reforested wood species, Pinus elliottii and Eucalyptus citriodora, coated with castor oil-based polyurethane resins, as an alternative material for distribution line cross-arms, from the standpoint of their mechanical and electrical properties and their low cost. Numerical simulations and a complete description of the entire coating process are also part of this work.

Artificial neural network-based software tool for calculating the lightning performance of high-voltage transmission lines

An artificial neural network (ANN) is addressed for evaluating the lightning performance of high-voltage transmission lines. Several structures, learning algorithms and transfer functions were tested to produce a model with the best generalising ability. Actual input and output data, collected from operational Hellenic high-voltage transmission lines, were used in the training, validation and testing process. The method is coded in a comprehensive software program to be used by electric power utilities as a useful tool for the design of electric power systems, as an alternative to the conventional analytical methods. The aims of the paper are to describe in detail the proposed ANN method and the developed software tool and to present the results obtained by its application to operational Hellenic transmission lines of 150 kV and 400 kV. The ANN tool's results are compared with results produced from a conventional method and real records of outage rate showing a quite satisfactory agreement. overvoltages in distributions lines (13) and for lightning protection of high-voltage transmission lines (14). The calculation of the lightning performance of overhead transmission lines presents many uncertainties owing to the random nature of the lightning phenomenon and the lack of reliable data. This is why all the existing methods for the calculation of lightning performance are based on empirical and approximating equations. ANNs can be an effective alternative solution to this problem, as they can present great accuracy and, in many cases, better results using only actual line data in the lightning performance calculations. Moreover, the efficient and economic implementation of ANNs with today's computer technology makes them very attractive tools. In this paper, an ANN method is proposed to identify the lightning performance of high-voltage transmission lines. By testing several combinations of different structures, learning algorithms and transfer functions, we have developed an ANN that presented the best generalising ability among all the other combinations. Actual input and output data, collected from operational Hellenic high- voltage transmission lines w ere used in the training, validation and testing process. The developed method was coded in a comprehensive software program and applied to several operational Hellenic transmission lines of 150 kV and 400 kV so that its accuracy could be validated. The results obtained are compared with those produced using conventional methods and with real records of outage rate.

VOLTAGE STABILITY ASSESSMENT AND ENHANCEMENT OF THE THAILAND POWER SYSTEM

This paper presents voltage stability study of the Thailand power system by considering the existing Static Var Compensators, generation and load directions. An approach to determine appropriate voltage settings of existing Static Var Compensators is proposed in order to maximize static voltage stability margin of the system. Two most recent methods, namely Maximum Loading Margin and realistic load direction methods, are applied to the Thailand power system in order enhance loading margin of the system in a practical way. With the applications of the proposed and existing techniques, the highest and practical voltage stability margin of Thailand power system is obtained. This provides a guide for electric power utilities to enhance voltage stability margin of power systems in a practical way.

Impact of intentional islanding of distributed generation on electricity market prices

The battle for electricity customers in an increasingly competitive and deregulated market environment is one of the challenges facing the electric power utilities of today. Customers expect a reliable and efficient supply of power from their utilities. One of the advantages that a distributed generator (DG) can provide to the electric utility and to customers is the possibility of improving the continuity of supply by implementing safe intentional islands in the event of upstream utility supply outage. Implementing intentional islanding of DG in a deregulated era will have an impact on electricity market prices. This problem is considered in this paper by solving the optimal power flow problem while accounting for islanded operation.

MAINTENANCE WORK COORDINATION IN ELECTRICITY DISTRIBUTION

The goal of every electric power utility is to ensure that their customers are able to consume electricity in desired place, at desired time for a competitive price. In order to guarantee the above stated, the supply, the environmental safety requirements and the economical affectivity have to be ensured. The current work focuses on the electronic collaboration among companies and their subsidiaries for the efficient execution of the maintenance work in electricity distribution network. The maintenance work supply chain is a dynamic environment that consists of collaboration companies, each one specializing in a certain set of activities.

Experimental Verification of the Proposed IEEE Performance and Testing Standard for ADSS Fiber Optic Cable for Use on Electric Utility Power Lines

All Dielectric Self Supporting (ADSS) fiber-optic cable jackets are subject to dry band arcing associated with wet, conductive pollution, quantified electrically by ohms per meter, in conjunction with the location of the ADSS in relation to conductor placement on high-voltage transmission structures. In order to determine the suitability of a particular ADSS jacket material to resist dry band arc damage in various levels of pollution as well as for incipient voltage levels, an electrical test, employing equivalency to the dry band environment, has been proposed. A set of desirable hypothetical results are briefly discussed. The tests results described herein, for common polyethylene jacketed ADSS, support the nature of the hypothetical data. It is noted that this is not "pass-fail" but a test that establishes performance criteria. It has been submitted to the fiber optics standards working group.

Modelling a reliable wind/PV/storage power system for remote radio base station sites without utility power

The development of photovoltaic (PV) cells has made steady progress from the early days, when only the USA space program could afford to deploy them, to now, seeing them applied to roadside applications even in our Northern European climes. The manufacturing cost per watt has fallen and the daylight-to-power conversion efficiency increased. At the same time, the perception that the sun has to be directly shining on it for a PV array to work has faded. On some of those roadside applications, particularly for remote emergency telephones or for temporary roadwork signage where a utility electrical power connection is not practical, the keen observer will spot, usually in addition to a PV array, a small wind-turbine and an electrical cabinet quite obviously (by virtue of its volume) containing a storage battery. In the UK, we have the lions share (>40%) of Europe's entire wind power resource although, despite press coverage of the “anti-wind” lobby to the contrary, we have hardly started to harvest this clean and free energy source. Taking this (established and proven) roadside solution one step further, we will consider higher power applications. A cellular phone system is one where a multitude of remote radio base stations (RBS) are required to provide geographical coverage. With networks developing into the so called “3G” technologies the need for base stations has tripled, as each 3G cell covers only 1/3 the geographical area of its “2G” counterpart. To cover >90% of the UK's topology (>97% population coverage) with 3G cellular technology will requires in excess of 12,000 radio base stations per operator network. In 2001, there were around 25,000 established sites and, with an anticipated degree of collocation by necessity, that figure is forecast to rise to >47,000. Of course, the vast majority of these sites have a convenient grid connection. However, it is easy to see that the combination of wind and PV power generation and an energy storage system may be an interesting solution for the more rural and remote applications – particularly those where an electrical supply is not available or practical – and this paper attempts to explore the current practicalities of such a power generation solution for those cellular phone base stations.

Slagging and fouling characteristics of seam 32/33, Panian coalfield, Semirara Island, Philippines

Twenty samples of seam 32/33, the main seam of Panian coalfield in Semirara Island, Antique Province, Philippines, were collected from a borehole drilled at the northeastern edge of the coalfield. The samples were analyzed to characterize the coal geochemistry of the seam and understand why the coals of Semirara Island exhibit a high tendency for slagging and fouling despite its low average ash content. Analysis of the slagging and fouling characteristics of this seam is important because it supplies five electric power utilities and several cement plants in the Philippines. Proximate analyses and vitrinite reflectance measurements designate the rank of the seam as sub-bituminous C, based on ASTM coal classification. H/C versus O/C ratios indicate that the seam is made up largely of huminite, denoting early stages of coalification. Chemical analysis of the ash reveals high contents of Na, Mg, Fe, Ca, Ba and Sr. The strongly negative correlation of these elements with the ash content indicates an organic affinity of the chemical elements of the seam. Owing to enrichment in alkali and alkali-earth elements, slagging and fouling indices indicate that the seam has medium to high propensity for slagging and a severe tendency for fouling. The detrimental characteristics of coal feedstock from Panian mine is mitigated by modifications to the boiler design and operational conditions and by blending with coals imported from Indonesia, China and Australia.

Analytical and Monte Carlo Approaches to Evaluate Probability Distributions of Interruption Duration

Regulatory authorities in many countries, in order to maintain an acceptable balance between appropriate customer service qualities and costs, are introducing a performance-based regulation. These regulations impose penalties-and, in some cases, rewards-that introduce a component of financial risk to an electric power utility due to the uncertainty associated with preserving a specific level of system reliability. In Brazil, for instance, one of the reliability indices receiving special attention by the utilities is the maximum continuous interruption duration (MCID) per customer. This parameter is responsible for the majority of penalties in many electric distribution utilities. This paper describes analytical and Monte Carlo simulation approaches to evaluate probability distributions of interruption duration indices. More emphasis will be given to the development of an analytical method to assess the probability distribution associated with the parameter MCID and the corresponding penalties. Case studies on a simple distribution network and on a real Brazilian distribution system are presented and discussed.

Incorporating Reliability Index Probability Distributions in Financial Risk Assessment with Performance Based Regulation

Regulatory authorities are increasingly adopting performance based regulations (PBR) in the new electric power utility environment. A PBR regime is intended to provide distribution utilities with economic incentives. It could also introduce potential financial risk due to the integration of a reward/penalty structure into the PBR plan. In this new environment, distribution utilities will need to adjust their reliability performance strategy to avoid possible financial risk, and could decide to invest in new capital projects to improve system reliability and be financially rewarded. This article illustrates the utilization of Monte Carlo simulation to develop the relevant reliability indices and their distributions due to reliability improvements in an electric distribution system. Quantitative consideration of the effect of system reliability improvements on the financial risk under imposed reward/penalty structures is presented. This work should be useful for electric power utilities working to reduce their risk and raise their profit in the new regulatory environment.

Management of Information Security for an Electric Power Utility—On Security Domains and Use of ISO/IEC17799 Standard

The issue of information security has become a major concern for the electric power utilities. An increasing amount of money is being spent on the handling of information security. But the issue is delicate. Even though a utility may spend a fortune, it cannot be sure that it is doing the right thing at the right level of expenditures. Therefore, increasing efforts are being put into raising the awareness of information security. Here, the work in Cigre/spl acute/ Joint Working Group D2/B3/C2-01 "Security for Information Systems and Intranets in Electric Power Systems" is presented. The paper focuses on: stressing the importance of handling information security within an electric utility, the dealing with various threats and vulnerabilities, the evolution of Power Utility Information Systems from isolated to fully integrated systems, the concept of using security domains for dealing with information security within an electric utility, and the use of the ISO/IEC 17799 standard.

Role of Semiconducting Screens on Water Treeing in Medium Voltage XLPE Cables

Water treeing is a predominant mechanism of premature failure of underground XLPE distribution cables. Recent studies show that insulation degradation is due to injection of hydrophilic ionic species into the insulation and its rupture under the action of electromechanical and electro chemical processes operating at the microscopic level in the presence of strong field enhancement. Therefore, the ionic contamination in semicon screens as well as in the matrix of insulation play dominant role. But, most of these findings are based on the studies carried out on molded insulation plaques. The present study focuses on the role of contaminants in the semiconducting screens of medium voltage XLPE insulated cables commonly used in electric power utilities. Effect of two purposely selected ionic aqueous species on the treeing parameters evolved in these cables as a result of accelerated stress aging in the presence or absence of outer semiconducting screens, has been studied. Results show that ionic impurities present in semicon screens that belong to transitional metallic group, do catalyze the treeing process. If the semiconducting screens are produced and extruded over insulation using extra clean carbon then these will act as a barrier toward the degradation of cable’s insulation. Based on the results and their analysis it is postulated that if some suitable ion trapping materials are blended in the base matrix of semiconducting screens, the water tree growth in polymeric insulation can be effectively retarded.

05/00200 Development of high-efficiency woody biomass co-firing technology for electric power utilities in Japan: Takahashi, Y. et al. Proceedings of the International Technical Conference on Coal Utilization & Fuel Systems, 2003, 2, (28), 1139–1148

05/00200 Development of high-efficiency woody biomass co-firing technology for electric power utilities in Japan: Takahashi, Y. et al. Proceedings of the International Technical Conference on Coal Utilization & Fuel Systems, 2003, 2, (28), 1139–1148

Nitric acid loss rates measured in power plant plumes

Measurements of HNO3, NOx, NOy, and CO2 in the plumes from electric utility power plants located in eastern Texas are used to determine the HNO3 loss rates in the planetary boundary layer during plume transport. These 1 Hz measurements were obtained from the National Center for Atmospheric Research Electra aircraft flying on clear afternoons in a well‐mixed planetary boundary layer during the Texas Air Quality Study in August and September of 2000. The analysis uses data obtained in 48 crosswind transects of plumes from seven different power plants on six flight days. The NOx lifetime was found to vary from 1.3 to 3.1 hours in these plumes, indicating that the measurements were obtained during periods of rapid photochemical activity. The HNO3 loss rate was 0.45 ± 0.21 hour−1 in power plant plumes that were advected over rural regions. Particle size distributions measured in the plumes indicated that gas phase HNO3 was not lost to particle formation. Meteorological effects and land use were also investigated as possible causes for the observed HNO3 loss rates, which were insensitive to the land cover and measured wind speeds and boundary layer heights. The HNO3 loss rate measured in most plumes was more than 4 times greater than what is calculated from deposition velocities and the measured boundary layer height.

Electric vehicles charge forward

This article reviews the status of electric vehicles/hybrid electric vehicles (EV/HEVs) worldwide and their state of the art, with emphasis on the engineering philosophy and key technologies. The importance of the integration of technologies of automobile, electric motor drive, electronics, energy storage and controls, and the importance of the integration of society strength from government, industry, research institutions, electric power utilities, and transportation authorities are addressed. The challenged of EV commercialization is discussed. EV is a multidisciplinary subject involving broad and complex aspects. However, it has core technologies; chassis and body technology, propulsion technology, and energy source technology. The electric propulsion system is the heart of the EV. It consists of motor drive, transmission and controller, plus the integration with engine power train in the case of the HEV.

Occupational injury surveillance among electric utility employees.

Currently, there are only limited injury surveillance data for the electric utility workforce. To address this gap, an Occupational Health Surveillance Database for electric power utilities was established for epidemiologic monitoring and intervention program evaluation. Injury rates varied across utility occupations, such as, managers, line workers, and meter readers, ranging from 0.18 to 9.63 per 100 employee-years based on more than 500,000 employee-years of observation. Compared with male workers, the risk of injury among female workers was lower overall, although their risk was higher in nonoffice occupations than their male counterparts. Across the period 2000 to 2002, three of four companies that experienced decreases in workforce size also experienced noticeable increases in injury rates. Our results suggest that benchmarking and prevention efforts should be directed at specific occupational groups and specific injury types.

The Stae of the Art of Electric Vehicles

In a world where environment protection and energy conservation are growing concerns, the development of electric and hybrid vehicles (EV/HEV) has taken on an accelerated pace. The dream of having commercially viable electric/hybrid vehicles is becoming a reality. EVs and HEVs are gradually available in the market. This article reviews the present status of electric and hybrid vehicles worldwide and their state of the art, with emphasis on the engineering philosophy and key technologies. The importance of the integration of technologies of automobile, electric motor drive, electronics, energy storage and controls, and the importance of the integration of society strength from government, industry, research institutions, electric power utilities and transportation authorities are addressed. The challenge of EV commercialization is discussed.