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Industrial and Commercial Power Systems Technical Conference, 2005 IEEE

Date 8-12 May 2005

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Displaying Results 1 - 25 of 42
  • 2005 IEEE Industrial and Commercial Power Systems Technical Conference - Cover

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  • Conference Record - 2005 IEEE Industrial and Commercial Power Systems Technical Conference - Title Page

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  • Copyright

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  • 2005 I&CPS Conference Committee

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  • Previous I&CPS Technical Conferences

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  • Technical program

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  • Index of technical papers

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  • Reactive power compensation for voltage control at resistance welders

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1159 KB)  

    Resistance welders are a source of voltage fluctuations and flicker in industrial power distribution systems. The high-reactance welding transformer that limits the welding current creates a low power-factor load. With hundreds of welders, factories may use synchronized welding cycles that lead to annoying flicker. Other facilities use random timing to prevent flicker, but suffer deep voltage-sags due to simultaneous welding operations. Severe voltage variations reduce the power delivered to the welders, causing reduced heating and poor quality welding joints. The paper examines the design and application of a ministatic VAr compensator to I&C improve the voltage quality on the welding circuits of industrial power distribution systems. The compact range of reactive power demands for robotic welders suggest the use of thyristor switched capacitors. The compensation provides the necessary voltage control for consistent welds with the added benefit of reduced load currents throughout the industrial distribution system. The compensator control is coupled with the welder controls to mitigate the random reactive power mismatches that are often seen with other SVC welding and arc furnace applications View full abstract»

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  • A novel power-factor-correction circuit with high-frequency resonant energy tank for DC-link inverter

    Page(s): 10 - 16
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1150 KB) |  | HTML iconHTML  

    A novel approach of power factor correction (PFC) with a high-frequency resonant energy tank for the DC-link inverter is proposed. As compared with the conventional PFC techniques, this approach is advantageous of lower current stress, lower switching losses, and higher control flexibility. With carefully designed circuit parameters, the proposed topology can exhibit high power factor. The adopted PFC circuit is implemented on a series-parallel load resonant inverter as an illustrative example. The experimental results are provided to validate the theoretical analyses. It is proven that the PFC circuit can achieve nearly unity power factor and very low harmonic distortion View full abstract»

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  • Rule-expert knowledge-based petri network approach for distribution system temperature adaptive feeder reconfiguration switching operation decision reasoning

    Page(s): 17 - 31
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1345 KB)  

    This paper refers to decisions about transferring loads among distribution feeders in switching operations in order to enhance operating performance by combining the daily load characteristics and the variations among customers due to temperature increases using a switching operation decision inference mechanism, based on a rule-expert knowledge-based Petri network (RKBPN) method. Typical customer load patterns obtained in a load survey study are considered to determine the daily load profiles of each distribution feeder, to represent the load behavior more accurately. The current flows of the line switches and distribution feeders are determined by load flow analysis over a single day. A practical distribution system with seven feeders and daily load profiles with temperature sensitivity is selected for performing computer simulations, to demonstrate the effectiveness of the presented methodology. The proposed inference mechanism for reconfiguring the feeder based on the RKBPN approach enhances feeder reconfiguration to promote system contingency and improves load balance by considering the load characteristics of the customers served View full abstract»

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  • Impact of photovoltaic power sources on a power system's capacity reliability levels

    Page(s): 32 - 37
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (956 KB) |  | HTML iconHTML  

    Energy limitations associated with unconventional energy sources e.g., photovoltaic and wind power) can play an important role in capacity adequacy evaluation of present and future electric system configurations. Solar photovoltaic power plants are electric power sources whose output depends on natural factors that are statistically interdependent of the load. Photovoltaic (PV) plants have the significant problematic characteristic that their power outputs are not dispatchable into a power grid by the system operators. Utility dispatchers have virtually no control in regard to the amount of power available from photovoltaic plants at any instant.. This paper presents a new methodology for assessing the reliability of utility and industrial generation systems that include PV plants. The proposed new models are energy based and use a load modification approach (Chowdhury, 1990; Palz, 1978; Jaffe, 1985) for assessing the impacts of photovoltaic electric power plants upon a utility supply system. The method and the models for PV power plant output modeling are illustrated with a simple system example. The methodology is directly applicable to utility and industrial operating system configurations View full abstract»

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  • Application of islanding protection for industrial & commercial generators a working group report

    Page(s): 38 - 51
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1368 KB) |  | HTML iconHTML  

    Many owners of distributed resources such as synchronous industrial plant or commercial facility generators (ICG) are concerned about the requirements for protective relaying when connecting to a local utility. The connection may only be for a short transfer time of a few seconds during paralleling for periodic testing. A tendency is to look at the consequences of just their own ICG trying to serve a much larger utility load without considering that there may be other ICG connected to the same circuit. The power rating of an ICG is not important when considering protective relays required, because several small engine generators of 100 kW or a single larger ICG of 10.0 MW could form an island. Thus, all ICG connected to an electric power system usually are required to have the same protection in place at their point of common coupling. Different scenarios of islanding operation are presented, such as: is it necessary to enforce separation of loads that are outside the premises of the owner of the energy source, while retaining service to loads within the owner's premises, or is it acceptable to simply shut down the ICG until the grid can be restored? A basic step in addressing islanding protection is to have a clear expectation of what is supposed to happen when an island is created. This paper elaborates on the proper required protection and how its operation will prevent undesired consequences to the ICG owner, the utility and to the general public. The paper also discusses actions that take place when the utility supply is disrupted creating an islanding condition, and states reasons why protection required by regulatory agencies, local utilities and documents such as IEEE Standard 1547 "IEEE standard for interconnecting distributed resources with electric power systems" are required of an individual ICG. Consequences of not having the protection in place can permit damage to the generator and/or its prime mover, plus be a hazard to public safety. Examples of th- ese consequences are given. This paper will provide a clearer understanding to ICG owners of why they are required to have specified protective equipment in place View full abstract»

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  • How not to nuisance-trip distributed generation

    Page(s): 52 - 61
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (961 KB) |  | HTML iconHTML  

    This paper provides insight on how to prevent nuisance-trips from occurring on distributed generation (DG). The protection system at the DG interconnection must provide security to allow the DG to be connected to the utility grid, as well as reliably disconnect the DG from the utility grid for a variety of reasons. Most protection systems are set to trip the DG offline in less than one second, and often much quicker (10-30 cycles). Events can occur on the system and within the DG Facility, however, that may lead to undesired trips. These trips occur due to protection elements being set with very close tolerances and the interplay of events that include power surges from cycling of loads within a DG facility, faults within the DG facility that should be cleared by other means, and misapplication of protective elements. Various scenarios that can lead to nuisance tripping of DGs are discussed as well as a feature of modern protective systems that is an event analysis aid, waveform capture, applied at the point of common coupling at the DG facility and the utility View full abstract»

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  • Motor bus transfer: considerations & methods

    Page(s): 62 - 76
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1246 KB) |  | HTML iconHTML  

    This paper addresses the types of motor bus transfer (MBT) available, explores its technical challenges, and analyzes the creation of proper settings when implementing a MBT system for power plant spinning motor auxiliary buses or industrial plant spinning motor buses. Classic approaches are described and conditions are explored that make these transfers proper or improper. Advanced implementations of MBT methodology are explored that use high-speed sensing, decision-making and breaker control to account for the dynamic conditions in and about the plant, such as motor dispatch and loading, new source conditions and faults View full abstract»

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  • Differences in low-voltage fused and unfused power circuit breakers

    Page(s): 77 - 80
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (868 KB) |  | HTML iconHTML  

    This paper will discuss a few key differences between low-voltage fused and unfused power circuit breakers. A few standards are available to help understand the differences. In addition, an example application will be reviewed to show how different testing methods affect the evaluation of fused verses unfused power circuit breakers View full abstract»

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  • ARC flash hazard: the simplified model of ARC current

    Page(s): 81 - 88
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1009 KB) |  | HTML iconHTML  

    A simplified approach of arc modeling is suggested to facilitate the study of the dynamic behavior of the arc current. The behavior of the arc current is obtained as an extension of bolted short-circuit analysis; the waveform of the arc voltage is limited to the fundamental harmonic in phase with the fault current, considering the resistive characteristic of the arc. The arc current calculations by the simplified model are compared with the low voltage equation of the IEEE 1584 standard and tests results conducted by the IEEE 1584 WG. The comparison appears favorable. It encourages an improvement of the model in benchmarking its parameters with experimental results. The simplified method allows to analyze the behavior of the arc fault and to determine easily basic parameters, such as conduction angle, peak value, and the arc power and the arc energy View full abstract»

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  • Electrical design - refined for safety

    Page(s): 89 - 98
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1177 KB) |  | HTML iconHTML  

    A typical electrical system and equipment layout is designed to conform with certain standards such as National Fire Protection Association's NFPA 70 or International Electrotechnical Commission's IEC 60364-1. The occupational safety and health administration also sets forth design safety standards for electrical systems under 29 CFR Subpart S 1910.302-308. These documents contain fundamental principles of safety for protection against electric shock, thermal effects, overcurrent, fault currents, and overvoltage. After an initial electrical system design is complete, and the electrical system studies, including short circuit, protective device, and arc flash calculations are performed, current knowledge of arc flash hazard may dictate that the electrical design be refined for safety. An electrical design-refined for safety would consider methods to eliminate or reduce electrical failures, to lower any fault current magnitude, and to increase speed of protective device clearing. The purpose of this presentation is to identify and document the benefits to be gained from the use of such things as high resistance grounding, "see-through" rigid barriers, "fingersafe" fuses, insulated buses and terminal covers, arc resistant switchgear and controlgear, "enhanced safety" motor control centers, and/or appropriate personal protective clothing/personal protective equipment. "Electrical design-refined for safety" is an innovative and cost effective way to complement and supplement regulations and codes requirements. It can enhance employees' safety without excessive reliance on administrative controls. It can eliminate or reduce the burdens associated with obtaining special permits required for common tasks, such as meter reading, lock out/tag out, etc. "Electrical design-refined for safety" is the careful application of engineered safety features to enhance safety for personnel who must, from time to time, work in an environment affected by proximity to exposed energized e- lectrical conductors and circuit parts View full abstract»

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  • The lightning protection of a complex of structures (LPCS)

    Page(s): 99 - 105
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1006 KB) |  | HTML iconHTML  

    The standard IEC 61024 provides information for the design of lightning protection of structures (LPS). In determining the position of the air-termination system two methods are generally suggested: the protective angle method and the rolling sphere method. The paper discusses some additional criteria for the LPS with reference to a case study of a complex of strategic buildings constituted by existing and historical structures. The paper suggests the mark map that allows to determine globally the interactions between the structures of the complex. It is a graphical method performed by rolling a sphere with a variable radius related to the protection level and to the height of the structure View full abstract»

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  • Mitigation of flash hazard using transformers on industrial machines

    Page(s): 106 - 115
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1190 KB) |  | HTML iconHTML  

    The control of incident energy and subsequent flash-protection boundary for systems using large blocks of power has been established, which uses either the direct protection of fuses or the controlled switching of a circuit breaker. This paper will explore the use of isolation transformers on industrial machines to achieve similar results View full abstract»

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  • An integration of ANN wind power estimation into UC considering the forecasting uncertainty

    Page(s): 116 - 124
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1134 KB) |  | HTML iconHTML  

    The development of wind generation has rapidly progressed over the last decade. With the advance in wind turbine technologies, wind energy has become competitive with other fuel-based generation resources. The fluctuation of wind, however, makes it difficult to optimize the use of wind power generation. Current practice ignores the possible available capacity of the wind generation during the unit commitment scheduling. This may cause operation issues and waste usable capacity when the installation of the wind generation increases. An accurate wind capacity forecasting is essential for efficient wind energy and capacity dispatching. To ensure the system reliability, one also has to consider the forecast uncertainty when integrating the wind capacity into generation planning. This paper discusses the development of an artificial neural network based wind forecast model with the consideration of wind generation uncertainty by using probabilistic concept of confidence interval. The data from a wind farm located in the Southern Oklahoma is used for this study View full abstract»

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  • Artificial neural network based on-line partial discharge monitoring system for motors

    Page(s): 125 - 132
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1054 KB) |  | HTML iconHTML  

    Corona discharge (CD) and partial discharge (PD) indicate early stages of insulation problems in motors and generators. Early detection of CD/PD will enable better coordination and planning of resources such as maintenance personnel, ordering of parts, etc. Most importantly, one can prevent catastrophic failures during normal operations. In decades, on-line PD measurement has been used to find loose, delaminated, overheated, and contaminated defects before these problems lead to failures. As a result, on-line PD monitoring has become an important tool for planning machine maintenance. Many methods are available to measure the PD activities in the operating machines. The electrical techniques usually measure the currents by means of a high frequency current transformer at neutral points or detect the PD pulses via high voltage capacitors connected to the phase terminals. Those methods are generally expensive and easy to be interfered by the noise due to the considerations of the high frequency and low signal levels. Instead of using high frequency analysis, this paper extracts the low frequency characteristics of PD/CD faults and develops a low cost PD/CD on-line health monitoring system for motors. The system employs an artificial neural network (ANN) with multiple sensors inputs for PD/CD diagnostic task. The proposed algorithms and circuits are implemented and tested in the laboratory environment. Results show that the system is sensitive and accurate View full abstract»

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  • Load profile synthesis and wind power generation prediction for an isolated power system

    Page(s): 133 - 138
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1001 KB) |  | HTML iconHTML  

    This paper investigates the load composition by load survey study and predicts the wind power generation with a probabilistic network for an isolated power system. The power consumption by each customer-class with the application of load patterns and the total power consumption of all customers within the same class can be obtained and calculated. Probabilistic neural network (PNN) solves the wind power generation based on the wind speed for an offshore island in Taiwan. With the hourly wind speed and load composition, the power generation of diesel generators has been obtained. Results of this study demonstrate that wind power generation can economically and effectively replace the generation of the diesel power plant and provide partial power supply capability for the net peak load requirement View full abstract»

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