Domenico Mirri, Gaetano Iuculano, Pier Andrea Traverso, Gaetano Pasini
A different procedure, introduced previously by the authors for evaluating the errors due to the equally spaced sampling technique in the spectral analysis of a periodic signal and applied to the rectangular window, has been used to evaluate the effect of the cascade of two and three rectangular windows. This procedure is based on the assumption that the initial sampling instant can be randomized so that each estimated spectral component can be considered a random variable characterized by its statistical parameters. The theoretical expressions of these parameters were deduced and compared...
Andrzej Dobrogowski, Michal Kasznia
In the paper the data-dependent search for the Maximum Time Interval Error (MTIE) is described. In the first section the authors introduce the problem of time effective MTIE assessment. Then the data-independent method of MTIE assessment based on the estimator formula is described. In the next section the time effective data-dependent process of MTIE search is described. The results of the calculation experiment proved the time effectiveness of the proposed method.
Karel Sokanský, Josef Gavlas, Pavel Válek
The contribution deals with the basic description of a method for the diagnostics of the point of earth fault in the distribution network of 22 kV high-voltage long-distance lines. The method is based on the principle of impedance and uses the superposition of a suitably injected test signal on the line voltage. The method proposed is considered for localising the point of earth fault in the radial high-voltage long-distance lines that are operated with an ineffectively earthed neutral by the arc-suppression coil. The result of the method is not any absolute expression of the distance...
Karel Sokanský, Petr Dušek
Surge wave diagnostics is based on the principle of discharging two identical capacitors (highfrequency surge) into two loads (windings), and subsequent displaying resonant damped processes on loads by means of the two-channel oscilloscope. To increase the ability to identify failures, this signal must be, however, digitised and analysed by means of a mathematical tool. Generally, it has been stated that through this method, one of ten turn-to-turn short circuits can be identified without digitising the signal; after signal digitising, the identification of failures being improved...
Antonio Boscolo, Ivan Vlahinic, Saša Vlahinic
The deregulation of power market requires methods for the identification of the harmonic distortion source, while the increased presence of power electronics as major harmonic sources raises the level of harmonic distortion present in the electric power systems. Different approaches have been proposed for the identification of the source of harmonic distortion, but if direction of power flow is considered, only the harmonic active power is taken under consideration. In this paper, examples are described and simulations are undertaken to examine what is the actual information conveyed by the...
J. Pereira, O. Postolache, P. Girão, H. Ramos
A common solution to measure electrical power is through the use of systems that digitise voltage and current signals. However, several errors can affect the accuracy of such systems, namely transducer errors, sampling errors [1] and analogue-to-digital conversion errors. Sampling errors can be very important especially when low-cost solutions for digitalisation are considered. In this case, besides truncation errors caused by spectral leakage, non-simultaneous sampling of voltage and current signals, due to the absence of sample-and-hold-circuits, can also introduce large amplitude errors....
Rastislav Michálek, Peter Gábor, Peter Fuchs, Ján Hribik, Miloslav Hruškovic
The description of the designed digital threephase registration/calibration electricity meter based on the most recent Texas Instruments TMS320C6711 DSP is given. The description of the rms value calculation and the measurement errors are also given.
Dražen Dorić
A Supervisory Control and Data Acquisition (SCADA) based system for monitoring and control of the energy supply and the peak load in industry plant has been designed and algorithm for short-term energy forecast was implemented. The paper describes design and implementation of Energy Management System (EMS) consisted of cost effective elements combined with SCADA software application, which makes platform for supporting the economical energy management of industrial businesses. Trend SCADA screen with necessary on-line data for operator peak load limiting action was designed and real time...
Davor Pipić, Višnja Henč-Bartolić, Mirko Stubičar
Measurements of the output beam energy of the nitrogen laser were carried out. It is a pulse-operating molecular laser in UV region at a wavelength of λ=337,1 nm, pulse duration of τ=6 ns and output energy of up to 9 mJ, depending on operating conditions.
Evangelos Hristoforou, Kiamal Pekmestzi
In this paper, we present new auto-scaling field sensors based on the magnetostrictive delay line (MDL) technique. The principle of operation is based on the variation of the magneto-elastic response of an array of MDLs with respect to the applied input, which depends on the composition and the annealing history of the material.