8,247 research outputs found

    Power quality and electromagnetic compatibility: special report, session 2

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    The scope of Session 2 (S2) has been defined as follows by the Session Advisory Group and the Technical Committee: Power Quality (PQ), with the more general concept of electromagnetic compatibility (EMC) and with some related safety problems in electricity distribution systems. Special focus is put on voltage continuity (supply reliability, problem of outages) and voltage quality (voltage level, flicker, unbalance, harmonics). This session will also look at electromagnetic compatibility (mains frequency to 150 kHz), electromagnetic interferences and electric and magnetic fields issues. Also addressed in this session are electrical safety and immunity concerns (lightning issues, step, touch and transferred voltages). The aim of this special report is to present a synthesis of the present concerns in PQ&EMC, based on all selected papers of session 2 and related papers from other sessions, (152 papers in total). The report is divided in the following 4 blocks: Block 1: Electric and Magnetic Fields, EMC, Earthing systems Block 2: Harmonics Block 3: Voltage Variation Block 4: Power Quality Monitoring Two Round Tables will be organised: - Power quality and EMC in the Future Grid (CIGRE/CIRED WG C4.24, RT 13) - Reliability Benchmarking - why we should do it? What should be done in future? (RT 15

    Robust Convergence of Power Flow using Tx Stepping Method with Equivalent Circuit Formulation

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    Robust solving of critical large power flow cases (with 50k or greater buses) forms the backbone of planning and operation of any large connected power grid. At present, reliable convergence with applications of existing power flow tools to large power systems is contingent upon a good initial guess for the system state. To enable robust convergence for large scale systems starting with an arbitrary initial guess, we extend our equivalent circuit formulation for power flow analysis to include a novel continuation method based on transmission line (Tx) stepping. While various continuation methods have been proposed for use with the traditional PQV power flow formulation, these methods have either failed to completely solve the problem or have resulted in convergence to a low voltage solution. The proposed Tx Stepping method in this paper demonstrates robust convergence to the high voltage solution from an arbitrary initial guess. Example systems, including 75k+ bus test cases representing different loading and operating conditions for Eastern Interconnection of the U.S. power grid, are solved from arbitrary initial guesses.Interconnection of the U.S. power grid, are solved from arbitrary initial guesses

    Electrical and infrared properties of thin niobium microbolometers near T(sub c)

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    Niobium microbolometers approximately 1 micron wide x 2 micron long x 10 nm thick have been integrated at the feeds of equiangular spiral antennas made of 200 nm thick Nb. The device's current-voltage characteristics and infrared responsivity as a function of DC bias voltage were measured over a range of temperature spanning approximately plus or minus 2 percent around T(sub c). The greatest voltage responsivity occurs well below T(sub c), in a regime where the I-V curve is significantly hysteretic due to self-heating and resembles the I-V curve of a superconducting microbridge

    Time domain analysis of switching transient fields in high voltage substations

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    Switching operations of circuit breakers and disconnect switches generate transient currents propagating along the substation busbars. At the moment of switching, the busbars temporarily acts as antennae radiating transient electromagnetic fields within the substations. The radiated fields may interfere and disrupt normal operations of electronic equipment used within the substation for measurement, control and communication purposes. Hence there is the need to fully characterise the substation electromagnetic environment as early as the design stage of substation planning and operation to ensure safe operations of the electronic equipment. This paper deals with the computation of transient electromagnetic fields due to switching within a high voltage air-insulated substation (AIS) using the finite difference time domain (FDTD) metho

    TRIGA-SPEC: A setup for mass spectrometry and laser spectroscopy at the research reactor TRIGA Mainz

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    The research reactor TRIGA Mainz is an ideal facility to provide neutron-rich nuclides with production rates sufficiently large for mass spectrometric and laser spectroscopic studies. Within the TRIGA-SPEC project, a Penning trap as well as a beam line for collinear laser spectroscopy are being installed. Several new developments will ensure high sensitivity of the trap setup enabling mass measurements even on a single ion. Besides neutron-rich fission products produced in the reactor, also heavy nuclides such as 235-U or 252-Cf can be investigated for the first time with an off-line ion source. The data provided by the mass measurements will be of interest for astrophysical calculations on the rapid neutron-capture process as well as for tests of mass models in the heavy-mass region. The laser spectroscopic measurements will yield model-independent information on nuclear ground-state properties such as nuclear moments and charge radii of neutron-rich nuclei of refractory elements far from stability. This publication describes the experimental setup as well as its present status.Comment: 20 pages, 17 figure

    Pendekatan psikologi dakwah menangani histeria remaja muslim di Selangor

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    Gejala histeria dalam kalangan remaja di Malaysia merupakan epidemik sosial yang telah lama berlaku dalam masyarakat. Kejadian tersebut mengganggu proses pengajaran dan pembelajaran, psikologi, jasmani dan spiritual remaja. Pelbagai pendekatan pencegahan dilakukan oleh remaja dan pihak sekolah dalam menangani gejala yang berlaku, namun tidak menunjukkan pengurangannya. Oleh itu kajian ini bertujuan mengenal pasti konsep histeria, menganalisis faktor dan simptom histeria remaja, mengenal pasti pendekatan psikologi dakwah untuk menangani histeria, mengkaji kaedah pencegahan yang dilakukan remaja terhadap gejala histeria serta menganalisis hubungan antara faktor, simptom dan langkah pencegahan. Reka bentuk kajian adalah kajian tinjauan dengan menggunakan instrumen soal selidik dan temu bual. Seramai 122 orang responden yang mengalami histeria dari 10 buah sekolah di Selangor dipilih secara persampelan kelompok dan seramai 9 orang pelajar yang mengalami histeria ditemu bual. Temu bual turut dijalankan terhadap kaunselor, pakar psikiatri dan perawat perubatan Islam bagi menyokong dapatan kajian. Hasil kajian mendapati terdapat lima faktor histeria dalam kalangan remaja Muslim iaitu faktor psikologi, tekanan keluarga dan persekitaran, kepercayaan dan kebudayaan dan amalan keagamaan. Manakala dari aspek simptom, terdapat tiga bentuk simptom iaitu simptom gangguan emosi, psikiatri dan gangguan makhluk halus. Dari sudut pencegahan, remaja yang mengalami histeria kerap menggunakan pencegahan secara tazkiyah al-nafs, perawatan Islam dan psikiatri. Hasil analisis hubungan antara faktor dan simptom histeria mendapati faktor yang berhubung secara signifikan dengan ketiga-tiga simptom histeria adalah faktor psikologi, tekanan persekitaran dan kepercayaan dan kebudayaan. Manakala dari aspek pencegahan terdapat hubungan yang signifikan antara pencegahan tazkiyah al-nafs dan perawatan Islam dengan simptom gangguan emosi. Implikasi kajian dapat membantu pelbagai pihak dalam menangani punca dan simptom histeria remaja dengan menggunakan pendekatan psikologi 3 dakwah

    Distributed photovoltaic systems: Utility interface issues and their present status

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    Major technical issues involving the integration of distributed photovoltaics (PV) into electric utility systems are defined and their impacts are described quantitatively. An extensive literature search, interviews, and analysis yielded information about the work in progress and highlighted problem areas in which additional work and research are needed. The findings from the literature search were used to determine whether satisfactory solutions to the problems exist or whether satisfactory approaches to a solution are underway. It was discovered that very few standards, specifications, or guidelines currently exist that will aid industry in integrating PV into the utility system. Specific areas of concern identified are: (1) protection, (2) stability, (3) system unbalance, (4) voltage regulation and reactive power requirements, (5) harmonics, (6) utility operations, (7) safety, (8) metering, and (9) distribution system planning and design
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