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Power System Technology, 2000. Proceedings. PowerCon 2000. International Conference on

Date 4-7 Dec. 2000

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  • PowerCon 2000 International Conference on Power System Technology [front matter]

    Page(s): i - xiv
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    Freely Available from IEEE
  • Author index

    Page(s): i - vi
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    Freely Available from IEEE
  • Loss-of-load probability calculation using learning vector quantization

    Page(s): 1707 - 1712 vol.3
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    This paper proposes a new method employing learning vector quantization (LVQ) and Monte Carlo simulation to calculate the loss-of-load probability (LOLP) of power systems. LVQ is a type of classification method whose goal is to use data samples to position the codebook vector in such a way that the nearest neighbor classification method will result in the maximum classification accuracy. The proposed method greatly reduces the computing burden of the loss-of-load probability calculation compared to Monte Carlo simulation only. A case study of the IEEE RTS system is presented, demonstrating the efficiency of this approach View full abstract»

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  • Grounding of optical fiber control cable in substation under lightning stroke

    Page(s): 1511 - 1516 vol.3
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    The optical fiber control cable in a substation would be destroyed due to the incorrect grounding method, when a lightning strike hits the substation. The method to generate interference on an optical fiber cable by lightning stroke was analyzed. Different grounding methods were comprehensively discussed by a numerical calculation method. The ideal grounding method for optical fiber cable is to ground the internal strengthening core and the outer metal sheath in the meantime. The electrical field intensity applied inside the optical fiber cable increases with the soil resistivity. The frequency of the interference source is an important factor to affect the interference electrical field generated inside the optical fiber cable. The metal strengthening core has a high potential when an interference source is applied, so the stroke from it to the interior of the terminal equipment should be avoided View full abstract»

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  • Novel approach to partial discharge signals modeling in dielectric insulation void using extension of lumped capacitance model

    Page(s): 1207 - 1212 vol.3
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    Using a lumped capacitance circuit model simulated under the Electromagnetic Transient for DC (EMTDC) program, waveforms of the Whitehead equivalent void model are generated and analyzed. Type of discharge varies within a void and is not readily known due to the uncertainty in the parameters. This paper attempts a model to segregate types of partial discharge (PD) within dielectric insulation on the signal waveform level. The EMTDC program provided a platform to trace the transient stressing of various parts within a void. The uncertain mechanism of discharge signal manifestation, localized at insulation imperfection area, of polymeric insulation is represented by capacitors with variable breakdown conditions. Voids with known sizes are modeled and simulations are carried out to see the transient behavior of breakdown. The modified model helps to visualize the kind of PD activity that goes on within the dielectric occluded void View full abstract»

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  • Development and application effect of polymeric surge ZnO arresters for 500 kV compact transmission line

    Page(s): 1449 - 1454 vol.3
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    500 kV polymeric ZnO surge arresters for a compact transmission line against lightning were developed and have been put into operation. The design of the arrester unit and the series gap are discussed. The calculated results states that the line surge arrester can highly improve the lightning withstand level of compact transmission line, and the line arrester can withstand the effects of lighting View full abstract»

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  • Analysis on influence of long vertical grounding electrodes on grounding system for substation

    Page(s): 1475 - 1480 vol.3
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    A three dimensional grounding system is introduced to decrease the grounding resistance, step and touch voltages of grounding systems in areas with high soil resistivity or with limited areas for grounding systems. The relationship between the number of vertical grounding rods and the grounding resistance is discussed. The new means to add grounding rods to the grounding system with an explosion grounding technique, have efficiently decreased the grounding resistance in the actual grounding engineering. Reasons why vertical grounding rods can efficiently decrease the maximum touch and step voltages of the earth surface above the grounding system are analyzed. Calculated results shows the vertical grounding rods can also effectively decrease the influence of seasonal factor on safety of grounding system. This paper provides the rule to choose the vertical grounding rods in multi-layer soil based on the relationship analysis between the number and the length of the vertical grounding rods View full abstract»

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  • Optimal design analysis of grounding grids for substations built in nonuniform soil

    Page(s): 1455 - 1460 vol.3
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    The optimal design of grounding system can ensure the safety of a substation. The influences of reflective coefficient of double-layer soil and the thickness of top-layer soil and the grounding grid area on the optimum arrangement of grounding system were analyzed by a numerical method. It states the optimum compression ratio (OCR) should be determined by the target function of touch voltage reaching the minimum value. The OCR decreases with the increase of reflective coefficient, when the soil resistivity of the bottom-layer soil is smaller than that of upper-layer soil, the arranged horizontal conductors are more uniform than that when the soil resistivity of the bottom-layer soil is higher than that of upper-layer soil. The formulae to calculate the OCR of double-layers soil structure are obtained from analysis results, which can provide reference for engineers to design the grounding systems of substations with high safety View full abstract»

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  • Development of risk profiles associated with electrical power substation earthing systems

    Page(s): 1341 - 1346 vol.3
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    Electric shock safety criteria and earthing system design methods should provide a level of safety that appropriately reflects the probability of a hazard occurring. This paper provides a risk management framework for the process of hazard identification. It also develops a methodology for modelling the probability of death from a wide range of hazards associated with the electrical power network. The case studies examine the level of shock hazard associated with people moving in or around a substation, and determines the sensitivity of the risk to a range of parameters which might be expected to have significant impact upon that particular shock scenario. The methodology is illustrated using actual case studies, coordinated with a combination of analytical computer modelling (as distinct from simplified empirical techniques) and field current injection test results View full abstract»

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  • Power system stabilization by synchronous condenser with fast excitation control

    Page(s): 1563 - 1568 vol.3
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    This paper presents a method to stabilize a power system with long distance bulk power transmission from an isolated large power plant by a synchronous condenser with fast excitation control. Excitation controls of a generator have achieved great success as a power system stabilizer (PSS). Synchronous condensers have been applied in large numbers to power systems for the control of system voltage and reactive power with high reliability so far. In this study the synchronous condenser with a devised excitation control has been applied for the stabilization of a generator power swing by installing the synchronous condenser at a bus in the transmission line near the generator. A design method based on the damping and synchronizing torques is proposed. The application of H-infinity control is also considered to develop a robust control system View full abstract»

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  • Adaptive power system stabilizer based on fuzzy logic technique with frequency domain analysis

    Page(s): 1299 - 1304 vol.3
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    For improving electric power system stability, synchronous generators in power systems are generally equipped with controllers such as AVR, PSS, and GOV. Since the various oscillation modes occur according to system conditions, these fixed parameter controllers deteriorate the control performance. We propose the adaptive power system stabilizer (PSS) using frequency domain analysis for improving electric power system transient stability. In the proposed method, at first, the frequency components of the generator's swings are detected by online FFT. The conventional PSS parameters are tuned online by the fuzzy logic technique based on the frequency domain analysis. We verify that the proposed adaptive PSS using frequency domain analysis can damp the generator's swings effectively View full abstract»

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  • Simulation of resonance in a small-scale network laboratory

    Page(s): 1635 - 1639 vol.3
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    The department of Electric Power Engineering at the Tampere University of Technology (Finland) has a project for reducing problems caused by harmonics, using a small-scale industrial network laboratory. There it is possible to investigate phenomena which take place in the industrial network. The laboratory consists of motors and other components that can be found in real networks. For harmonic filtering, there is a fifth harmonic filter with two steps. The harmonic filter produces basic frequency reactive power that can be used to compensate the reactive power needed by the laboratory, and to study the effects of the reactive power. The components of the laboratory have been modeled with PSCAD-EMTDC program. The aim of this paper is to present simulations, using the PSCAD-EMTDC program and the laboratory, how the capacitors for reactive power compensation can build up a series resonance circuit for some harmonics. The results of the simulation and laboratory studies are quite similar View full abstract»

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  • Probabilistic comparison and application of international electrical safety criteria

    Page(s): 1347 - 1352 vol.3
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    Investigations have been made into the impact of probabilistic aspects of the shock scenario, yet are rarely applied in practice. To provide reliable design criteria it is necessary to link the electrical shock safety criteria with acceptable risk levels applicable for people, in the context of an electrical power system under earth fault conditions. The paper addresses the basis of the various criteria and identifies inconsistencies that have been introduced when transferring laboratory data to published body current criteria. Interference theory and Monte Carlo simulation techniques are used to statistically appraise the actual level of safety afforded by various safety criteria when compared with the benchmark body current criteria. Directions for rationalisation or change are identified to ensure consistency with physiological criteria and to ensure that appropriate economic, as well as defensible levels of safety are applied to power system installations View full abstract»

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  • Study of relaxation mechanism on a power network

    Page(s): 1383 - 1388 vol.3
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    An attempt was made to study the on-site relaxation mechanism of equipment in a power network consisting of a 30 MVA alternator, a transformer, underground cable and 66 kV SF6 gas insulated switchgear (GIS). The objective of the study is to obtain a signature of the aging of the equipment. Toward this end, measurements were carried out before and after the treatment of the transformer oil, with and without the alternator connected to the transformer. Field difficulties encountered and observation from the tests are reported. The measured data was then used to identify the parameters of the extended Debye model. Furthermore, the validity of the frequency response analysis (FRA) on detecting transformer faults was investigated. It shows that the technique is very sensitive to fault occurrence and much information can be extracted from the test results View full abstract»

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  • Dynamic security contingency ranking and generation reallocation using time domain simulation based severity indices

    Page(s): 1275 - 1280 vol.3
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    Fast contingency screening and efficient preventive control are two of the necessary integral functions of dynamic security analysis (DSA). Contingency screening requires the use of severity indices, and for DSA such an index should be a measure of system stability. In this paper, three time-domain simulation based indices are proposed for ranking of contingencies and generation rescheduling in DSA. These indices are energy margin index (EMI) based on hybrid extended equal area criteria (EEAC), transient energy index (TEI) based on hybrid transient energy function (TEF), and critical clearing time (CCT). Results on realistic power systems are presented to show their relative merit for use in contingency screening and generation rescheduling View full abstract»

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  • Field experience with the new platform-mounted DVRTM

    Page(s): 1323 - 1328 vol.3
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    Installation of the world's first platform-mounted dynamic voltage restorer (DVRTM PM) prototype on a major North American utility system to protect a critical customer load from power system voltage disturbances ushers in a new era of power quality solutions available for overhead distribution systems on the utility side of the revenue billing meter. The DVRTM PM built by Siemens for the Electric Power Research Institute (EPRI) was installed at the Northern Lights Community College in Dawson Creek, B.C. where it provides protection for 600 kVA of load from disturbances coming from the utility 25 kV distribution system that serves the college. The early success of the DVRTM PM demonstration in Canada has implications for the Australian market where in excess of 90% of the 11 and 22 kV networks are bare conductor overhead lines. As a consequence, customers are exposed to the voltage sags that the DVRTM is designed to mitigate. Smaller critical customer loads can now be offered improved power quality network solutions on the 11 or 22 kV distribution systems that were not previously available. In Victoria alone, there are approximately 14,000 customers (or groups of commercial/industrial customers) who would benefit from such a network solution. This paper describes the DVRTM PM and the demonstration project installation, commissioning, and field operation to date. Future equipment designs are also discussed View full abstract»

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  • Investigation on electrical performance of semiconducting glazed insulators under natural pollution in Thailand

    Page(s): 1229 - 1232 vol.3
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    On economic reasons, high voltage overhead lines are widely utilized for transmitting electrical power for a long distance. In such a way, insulators have to be used as insulating supporters in various environments. In polluted area, the electrical performance of insulators will be degraded. The polluted insulators will have lower withstand voltage, flashover can occur easily when the air becomes wet by very higher humidity or fog, which affects on the reliability of the power system. It is supposed that such problems can be solved by utilizing semiconducting glazed insulators. This paper reports the three years results of experimental investigation on semiconducting glazed insulator exposed in differently polluted areas, in which equivalent salt deposit densities (ESDD) have been known, namely industrial chemical pollution, salt from sea and dust pollution. The investigation was carried out on small long rod insulators with rating at 33 kV. The test samples are porcelain and silicone insulators with leakage distances of 60 cm and 84 cm respectively. The flashover test on natural polluted insulators were performed in a clean fog chamber after the insulator samples had been hung in specified polluted areas for different periods, e.g. 5 month, 8 months, 10 months and 12 months. The investigation was conducted for three years. The tests procedure were performed in accordance with IEC 507-1991. The comparison of flashover voltage results under wet condition with clean fog are made between normal glaze and semiconducting glazed insulators and silicone insulator as well. The results show that flashover voltage of the semiconducting glazed insulators with different kinds of natural pollutions are about 2-3 times higher than of normal glazed insulators and a little bit higher than that of silicone rubber insulators View full abstract»

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  • An application of interior-point based OPF for system expansion with FACTS devices in a deregulated environment

    Page(s): 1407 - 1412 vol.3
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    This paper presents the formulation of AC optimal power flow (OPF) with deregulation issues and the effect of flexible AC transmission systems (FACTS) devices. A predictor-corrector interior-point nonlinear-programming (PCIPNLP) algorithm has been developed to solve the problem. Only minor changes are required to the present OPF function in a modern EMS for social welfare maximization to obtain the optimized bid-based dispatch and nodal spot prices. The incorporation of FACTS devices for system expansion can ease the difficulties caused by transmission congestion. It is found that PCIPNLP technique is very effective for the modified OPF solution for congestion relief under deregulation. Test results suggest that the incorporation of FACTS devices can not only utilize the existing lines, but also reduce load curtailment and increase market profit View full abstract»

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  • Truncation effects of FFT on estimation of dynamic harmonics in power system

    Page(s): 1155 - 1160 vol.3
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    This paper investigates the truncation effects of the fast Fourier transform (FFT) on harmonic estimation in the power system. Special efforts are concentrated on the voltage and the current with time-varying waveforms. The effects on the time response of the dynamic harmonic estimation are discussed. An overlap truncation method is proposed to achieve a faster response. A full-converter fed DC drive is used as an example to illustrate the implementation of the overlap truncation method and group-harmonic identification for dynamically evaluating the harmonic distortion of a power system View full abstract»

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  • An improved evolutionary programming approach for distribution loss reduction by feeder switching

    Page(s): 1419 - 1424 vol.3
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    This paper proposed an improved evolutionary programming (IEP) technique to minimize distribution feeder losses. In the minimization process, switches were indicated by pre-assigned integers. In this paper, the authors focused on the minimization of the real power loss, as well as on voltage and current constraints subjected to the radial network structure. Many tests were conducted to show its effectiveness View full abstract»

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  • Dynamic characteristic test of protective relay for double circuit using real time digital simulator (RTDS)

    Page(s): 1461 - 1464 vol.3
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    Dynamic characteristics of the digital distance relay and PCM current differential relay are described in this paper. It is difficult to achieve various fault simulation using conventional static type tests, while RTDS can handle not only various fault modeling but also dynamic characteristic test modeling because it is a full digital and real time simulator. Thus, this paper describes a test procedure, using RTDS, to verify the high possibility of malfunction cases for the distance relay and PCM current differential relay. In this paper, test modeling is established and then simulation for this test model is performed with RTDS. The results are compared with the ones calculated by PSS/E and by hand calculation View full abstract»

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  • Adaptive setting of digital relay for transmission line protection

    Page(s): 1465 - 1468 vol.3
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    The distance relay is the most widely relay used in transmission line protection because it is applicable not only as main protection but also as back-up protection. However, the protection range of the distance relay is always fixed in the unchangeable operating range while the power system varies and therefore the distance relay is the one that is the most highly influenced by the power system changes. In this regard, this paper describes an approach to minimize the maloperation of the distance relay due to the power system changes through changing protection range of the distance relay into optimal condition in response to the load variation and power system condition. Also malfunction of the distance relay in case of high resistance ground faults could be minimized through modeling the protection range into a quadratic function View full abstract»

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  • Research on drum feedwater distribution style of sub-critical pressure natural circulation boiler

    Page(s): 1521 - 1525 vol.3
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    The paper develops a down-comer feed style (DFS) of drum feedwater distribution of natural circulation boiler based on the study of working process in the drum, which can greatly release the drum metal thermal stress by balancing the temperature field of drum wall. The characteristics of the DFS compared to the normally used pressure distribution mode at present are discussed in detail. The paper analyzes the hydraulic characteristics after the down-comer feed style is adopted. It is concluded that DFS is safe on circulation and simple in design, and can be widely used in subcritical pressure natural circulation boilers View full abstract»

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  • Branch-and-bound dispatching for feeder capacitors on distribution system

    Page(s): 1569 - 1573 vol.3
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    A new branch-and-bound algorithm for the placed capacitors dispatch on a distribution feeder in daily system operation is presented in this paper. An efficient branching method based on the heap data structure and a simple intuitive bounding rule based on the forecast hourly loads are proposed to reach an optimum capacitor dispatching schedule and minimize the total feeder losses. The operation constraints, including bus voltage limits and maximum allowable number of switching operations for each switchable capacitor, have been taken into account to optimize the real-time scheduling problem under varying loading conditions. The feature of the devised solution algorithm is their numerically fast computation and mathematically justified optimality. To demonstrate the effectiveness of the proposed approach, capacitors dispatch on a distribution feeder of the Taiwan Power Company (TPC) is studied. Numerical computation gives satisfactory results and illustrates that the devised approach locates the optimum schedule in greater loss reduction and less computation time than many existing techniques View full abstract»

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  • Simulation and analysis of voltage sag mitigation using active series voltage injection

    Page(s): 1317 - 1322 vol.3
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    The analyses of voltage sag and its mitigation techniques have received a lot of attention in recent years. Through the fictitious three-phase voltages and the voltage conversion, a new method that can be used to instantaneously quantify the magnitude, duration and phase-angle jump of voltage sag is described in this paper. Considering the actual power quality disturbances, a low pass filter is used to obtain the RMS value of the voltage. The deficiencies of the classical RMS computations for classifying voltage sags are overcome with the proposed method. The method is efficient for the evaluation of voltage sags and the injection for correcting voltage sags in real time on series compensation devices. Taking into account the actual disturbances and the injection capability, the control strategy used in series device is given. Finally, simulation results ate presented to demonstrate the validity of the proposed method View full abstract»

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