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Propagation of current harmonics on power oscillations. Ideal sinusoidal voltages are assumed. 

Propagation of current harmonics on power oscillations. Ideal sinusoidal voltages are assumed. 

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Conference Paper
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The paper addresses the impact that time varying angular frequencies observed in electrical signals can have on the calculation and separation of components from the instantaneous electric power signal. Instantaneous power theories provide various methods for calculating the instantaneous power components in an electrical network. These methods are...

Context in source publication

Context 1
... I pharm is the amplitude of the current harmonic and α the phase shift of the harmonic content between the balanced three phases. Fig. 4 shows the harmonic components in a frequency spectrum representation based on the Fourier series, assuming constant frequency ...

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... The low inertia in such systems requires properly implemented controllers in order to maintain satisfying operation conditions. However, also the advanced inverter control may produce time-varying oscillations in conditions with varying load demand [1]. Hitherto, data acquisition-and measurement system have generally been based on the basic assumption of constant fundamental frequency and harmonics that are integer multiples of the fundamental frequency [2,3]. ...
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Modern electrical systems have introduced distributed generations and power converters. This brings out different issues such as low inertia of the grids and an increasing number of harmonics and non linear distortions injected. However, the fluctuations of instantaneous frequency are arguably the most characteristic feature of microgrids. Frequency drift during step load change as well all quasi-periodic fluctuation has an impact on various conditions as generators’ prime movers and governor’s characteristic. Quasi periodic frequency fluctuations can have besides detrimental effect on electrical receivers’ work, especially electric motors will be affected. The thesis aims at providing a deep insight into the phenomena of non-constant instantaneous frequency. Origin of instantaneous frequency fluctuations are analyzed, tools for the phenomenon identification are proposed. These considerations are based on careful analysis of data from the Norwegian power system and behavior of three real marine systems onboard of a ro-ro ship with shaft generator, research-training ship during work of auxiliary generating sets as well as integrated power system of ship with electrical propulsion. For each ship, the cases of rough and calm sea are compared. To analyze data, the empirical mode decomposition algorithm and the Hilbert transform implemented in Matlab will be used.
... The low inertia in such systems requires properly implemented controllers in order to maintain satisfying operation. In addition to the harmonic pollution, advanced inverter control may produce time-varying oscillations in conditions with varying load demand [1]. The role of these invertes are to serve as an interface between the generation source and the loads. ...
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... After an extensive study of IEC Standard 61000-4-7 measuring methods, [4] states that these methods do not produce accurate results in environments with time-varying angular frequency. Keeping the aforementioned problems of nonlinearities and time-varying quantities in mind, measurements and estimation in isolated microgrids should rather be based on instantaneous amplitude and frequency rather than the usage of average values [1,5]. With improved data acquisition-and measurement tools, the supervisory control systems in isolated microgrids may perform better actions, and earlier hidden distortions may be revealed. ...
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