Journal Volume 14 Issue 2

Single Sensor Based Photovoltaic Maximum Power Point Tracking Technique for Solar Water Pumping System

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Amine Daoud, Abdelhamid Midoun

The development of photovoltaic (PV) panels has made solar-powered pumps a reality. The pump drivers are usually direct-current (DC) motors, which are fed by power electronic converters with maximum power point tracking (MPPT) to extract the whole energy that the PV panels can generate, depending on environmental conditions including irradiation and temperature. The implementation of the MPPT algorithm essentially involves sensing both an input current and an input voltage. Understandably, such realisation is expensive.

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ATP/EMTP Study of Ferroresonance Involving HV Inductive VT and Circuit Breaker Capacitance

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Mariusz Stosur, Wojciech Piasecki, Marek Florkowski, Marek Fulczyk

Ferroresonance is a phenomenon usually initiated by transients in power networks resulting from, for example, switching operations or ground faults. Non linear behavior of the core of an inductive voltage transformer results in magnetic saturation. Long-lasting ferroresonant states are dangerous to equipment due to prolonged overvoltage and large overcurrents in HV windings. In the present article, numerical simulations of the ferroresonance phenomenon in a HV inductive VT are presented.

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A Hybrid Parallel Active Filter / Off-Line UPS Unit for Computer Loads

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Tarak Ghennam, Mohamed Darwish

A hybrid parallel active filter / off-line uninterruptible power supply (UPS) system is proposed here. The hybrid system contains a single inverter, which acts as a parallel active filter during the normal mode of operation (when the AC supply is available) and also supplies the load with energy from the UPS back-up battery during the back-up mode of operation (when the AC supply is not available, or is beyond the preset tolerance). In both modes of operation, the inverter is controlled in such a way that the line current is a pure sinusoid.

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Power Quality Enhancement of Three-PhaseFront-End Rectifier of UPS System Using Current Injection Technique

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Gunwant A. Dhomane, Hiralal M. Suryawanshi

Power Quality, in terms of power factor and harmonics, is greatly hampered by a three-phase rectifier used as a front-end ac-to-dc converter in many systems including a UPS. This paper presents the high power factor operation of the converter with reduced total harmonic distortion up to 4%. The power quality up gradation is due to high-frequency current injection at the input of the front-end rectifier. A small filter is required at the output for filtering the high-frequency content.

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An Assessment of Power Quality and Electricity Consumer’s Rights in Restructured Electricity Market in Turkey

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Omer Gul

Recently, electricity consumers have shown increasing concern for power quality. Indeed, power quality standards have become higher than before for certain customers due to sensitivity of automation devices. In addition, power quality is affected by the deregulation of power markets in Turkey. In this study, consumers are provided with basic knowledge of power quality and the cost of poor power quality while on the other hand, the existing regulations are evaluated in terms of consumers’ rights so that poor power quality costs and loss are identified and amended.

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Wiener Filtering Applied to Conducted EMI Estimation in Soft Switching Inverter

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Piotr Musznicki, Piotr J. Chrzan, Sławomir Mandrek

This paper presents a method of estimating the conducted electromagnetic interference EMI emissions in soft switching inverters. The estimation process is carried out by a number of Wiener filters, which represent different operational conditions as reflected through subsequent power converter states determined by initial commutation event conditions and propagation path layout. Filters are fed by a semiconductor power switch voltage or current waveforms regarded as sources of perturbation.

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Method of Selection of dv/dt for EMI Current Ringing Attenuation

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Adam Kempski, Robert Smolenski

In this paper, the method of selecting dv/dt for EMI current ringing attenuation is presented. The mechanism for attenuation is first identified using the theoretical approach. It is shown that the attenuation occurs for rise time of the voltage equal to the inverse of the frequency of current ringing. The concept has been experimentally verified in DC chopper and frequency converter arrangements. The proposed method of ringing attenuation can be applied in power converters with flexible gate control and can be also utilised in a wide area of electronic circuits with a trapezoidal excitation for a signal integrity improvement.

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A Hilbert Transform Based Algorithm for Detection of a Complex Envelope of a Power Grid Signals – an Implementation

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Andrzej Wetula

This paper presents an algorithm for the detection of a complex envelope of power grid signals. The algorithm is based on a Hilbert transform. It was prepared for an analysis of low-frequency disturbances, but can also be used as a compex envelope source for other applications. An implementation of the algorithm in a digital signal processor was made to prove an ability of a real-time operation. Analyses with various numerical representations and input signal quantisation were done. Execution times on a DSP were measured. Tests proved that the presented algorithm is able to analyse power grid signals in real-time with satisfying performance.

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The Hilbert transform adaptation for measuring amplitude and phase low-frequency disturbances in power system voltage

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Andrzej Bień

Phase disturbances in electric power signals are neglected and only amplitude (envelope) distortions are discussed in literature. Amplitude disturbances are interpreted as Amplitude Modulation (AM) of the main 50 Hz frequency. Detailed analyses of all disturbances and their sources are presented in this paper. It is shown that AM and narrow band PM (phase modulation) take place in power networks simultaneously, and those two modulations interact with each other. Voltage variation is proposed for disturbance measurement. Theoretical results are verified by field experiments and their results are presented here.

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The Case of Hidden Instantaneous Powers

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Murat E. Balci, Alexander E. Emanuel

This brief communication addresses the case of a dc nonlinear load supplied with a perfectly constant instantaneous power. A careful analysis shows that this condition does not provide optimum transfer of electric energy.

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