Papers by Sreeramulu R Naidu
Projeto Assistido por Computador de um Sistema de Medição para Tensões de 1MV
Revista Tecnologia, 1986
Time domain model for the ferromagnetic core, including the effects of hysteresis and eddy currents
IEE Proceedings A Science, Measurement and Technology, 1991
A time domain model for the ferromagnetic core is presented. The model includes the effects of hy... more A time domain model for the ferromagnetic core is presented. The model includes the effects of hysteresis and eddy currents. Simulation of the nonlinear B-H trajectories is based on Preisach's theory, and it requires only the limiting hysteresis loop as input data. The model has been checked against measurements of the inrush currents obtained for a small transformer. There is satisfactory agreement between the calculated and measured current transients.
Spacer Flashover Time Lags in SF6 Under Fast-Front Impulse Voltages
Gaseous Dielectrics V, 1987
ABSTRACT A measurement system for studying the breakdown of insulator surfaces in sulphur hexaflu... more ABSTRACT A measurement system for studying the breakdown of insulator surfaces in sulphur hexafluoride under fast front (10 ns rise time) voltages is described. Measurements of volt-time characteristics have been made using 3 and 10 mm diameter rod electrodes in a rod-plane configuration with several insulator materials and geometries. The results show that insulator surfaces can have a significant effect on flashover voltage, volt-time characteristics, and flashover probability at very short times to breakdown.
Estimation oftheUtility's andConsumer's Contribution toHarmonic Distortion
Email: Abstract -A method hasbeenpresented fortheallocation of responsibilities between autility ... more Email: Abstract -A method hasbeenpresented fortheallocation of responsibilities between autility andaconsumer withreference tothedistortion of3-phase voltage waveforms atthepoint of commoncoupling. Theinput datarequired forapplying this method arethemeasured voltage andcurrent waveforms atthe pointofcommoncoupling. Thefrequencies inthemeasured waveforms areestimated anda Kalmanfilter isusedto estimate thephasors atthese frequencies. Subsequently, the parameters oftheelectrical system oftheindustrial loadhave beenestimated usingtherecursive least-squares technique. Withthese estimated data, theindividual contributions tothe distortion ofthe3-phase voltage waveforms havebeen calculated. Theproposed method hasbeenillustrated bymeans ofapractical example.
A virtual bridge to compute the resistive leakage current waveform in ZnO surge arresters
2004 IEEE/PES Transmision and Distribution Conference and Exposition: Latin America (IEEE Cat. No. 04EX956)
The measurement and the harmonic analysis of the resistive leakage current present is an efficien... more The measurement and the harmonic analysis of the resistive leakage current present is an efficient parameter for determining the degradation level of metal oxide surge arresters. In this paper, the methodology and results of a novel circuit for measuring the resistive leakage current in metal oxide surge arresters is described. The technique requires the digital acquisition of the voltage applied to the surge arrester and the total current of the arrester. A virtual bridge has been implemented in software Matlab/sup /spl reg// to eliminate the capacitive component. In this implementation the resistive leakage current waveform is computed without the need for an expensive high voltage capacitor. The implementation suggested in this paper agrees well with measurements obtained with a coupling capacitor.
Positive and negative lightning impulse breakdown of rod-plane gaps in nitrogen
The breakdown characteristics of rod-plane gaps in nitrogen and N2-SF6 mixtures are being studied... more The breakdown characteristics of rod-plane gaps in nitrogen and N2-SF6 mixtures are being studied by the authors, [1]. Some preliminary results on the breakdown characteristics of these gaps in pure nitrogen, as a function of rod diameter, gap spacing, gas pressure, and polarity of the applied impulse voltages are presented in this paper.
International Conference on Power Systems Transients …, 1997
Eletrônica de Potência, May 1, 2008
Resumo-Uma estratégia de modulação por largura de pulso (PWM) aplicada a um inversor de tensão de... more Resumo-Uma estratégia de modulação por largura de pulso (PWM) aplicada a um inversor de tensão de quatro braços é proposta neste trabalho. A técnica é utilizada para a geração de tensões trifásicas desequilibradas, incluindo a componente de sequência zero. Ela pode ser facilmente implementada em um processador digital de sinais (DSP) e com custo computacional reduzido em relação a uma estratégia de modulação tridimensional utilizada para este tipo de inversor. A técnica proposta é aplicada com um controle em malha aberta de um restaurador dinâmico de tensão (DVR) laboratorial. Os resultados de simulação e experimental são apresentados para validar a técnica proposta. Palavras-Chave-Componente de sequência zero, inversor de quatro braços, restaurador dinâmico de tensão.
INTERNATIONAL CONFERENCE ON POWER SYSTEMS TRANSIENTS Lightning Protection of Compact Transmission Lines
Determination of the lightning performance of compact transmission lines is described. The tower ... more Determination of the lightning performance of compact transmission lines is described. The tower top transient voltage, following a lightning stroke is determined using the EMTP(ATP) program. Computer models of towers, ground wires and conductors, and the earthing system are presented. Computer simulations include a sensitivity analysis relative to the waveform of the lightning current, stroke location, earth resistivity, type of tower and terrain profile.
Steady-state Response Analysis Of Power Electronic Converters
Eletrônica de Potência
Fault location in distribution systems using the voltage sag-duration table
2014 11th IEEE/IAS International Conference on Industry Applications, 2014
—A fault location technique based on the voltage sag-duration table has been described. The techn... more —A fault location technique based on the voltage sag-duration table has been described. The technique is simple to apply and has the potential to be implemented on-line. It needs the data from power quality meters installed at a few measuring stations. The technique has been demonstrated by simulating faults in realistic distribution networks.
A technique for generating strong shock waves at atmospheric pressures
Journal of Physics E: Scientific Instruments
Elevação do potencial da carcaça de uma subestação isolada a gás SF6 devido a uma operação de chaveamento : simulação digital /
ABSTRACT
A New Approach for Determining the Periodic Steady-State of Circuits with Thyristor-Controlled Reactors
ABSTRACT
A Novel PWM Scheme for the 4-Leg Voltage Source Converter and its Use in Dynamic Voltage Restoration
ABSTRACT
Accurate Modeling of the Three Phase Induction Motor Including Saturation Effects
ABSTRACT
The 4-leg Voltage Source Converter and its Application to Dynamic Voltage Restoration
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A software phase locked loop for unbalanced and distorted utility conditions
2004 International Conference on Power System Technology, 2004. PowerCon 2004., 2004
A software phase locked loop (PLL) for custom power devices is described in this paper. The PLL u... more A software phase locked loop (PLL) for custom power devices is described in this paper. The PLL uses the previous and current samples of the 3-phase utility voltages and separates them into the sequence components. The phase angle and frequency of the estimated positive sequence component are tracked by the first two stages of the PLL. The third stage estimates
Fault location in distribution systems using the voltage sag-duration table
2014 11th IEEE/IAS International Conference on Industry Applications, 2014
—A fault location technique based on the voltage sag-duration table has been described. The techn... more —A fault location technique based on the voltage sag-duration table has been described. The technique is simple to apply and has the potential to be implemented on-line. It needs the data from power quality meters installed at a few measuring stations. The technique has been demonstrated by simulating faults in realistic distribution networks.
Instantaneous Sequence-Components Resolution of 3-Phase Variables and Its Application to Dynamic Voltage Restoration
2007 IEEE Instrumentation & Measurement Technology Conference IMTC 2007, 2007
ABSTRACT
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Papers by Sreeramulu R Naidu