<p>Naučna rasprava izložena u ovoj tezi bavi se analizom<br />kvaliteta električne energije. Visok nivo električne<br />energije podrazumeva da su napon napajanja i struja<br />potrošača idealne sinusoide sa tačno određenom<br />amplitudom i učestanošću. Bilo kakva odstupanja od<br />idealnog nazivaju se izobličenja i najčešće se<br />karakterišu sa harmonicima.<br />Poslednjih godina dolazi do naglog razvoja<br />poluprovodničkih komponenata. Takve komponente su<br />uticale na ubrzan razvoj snažnih uređaja energetske<br />elektronike. Ti uređaji su nelinearnog karaktera, što<br />dovodi do pojave harmonika u signalima napona i struja<br />elektroenergetskog sistema. Prvi problem kojim se bavi<br />ova teza je analiza talasnih oblika struja ispravljača.<br />Metode primenjene za analizu su wavelet transformacija<br />(VT) i modulated overlapped transformacija (MLT). MLT<br />nadoknađuje nedostatak VT da dekomponuje signal u<br />odgovarajuće podopsege koji mogu sadržati i više<br />harmonika i daje tačnu informaciju o svakom harmoniku.<br />Obe metode su pogodne za offline analizu. Za online analizu<br />predložen je hibridni metod baziran na diskretnoj<br />Furijeovoj transformaciji (DFT) i adaptivnom pojasnom<br />filteru (EPLL). Hibridni metod je zadržao dinamički<br />odziv DFT-a, dok je EPLL obezbedio sinhronizaciju sa<br />osnovnom učestanošću sistema. Hibridni metod daje<br />dovoljno tačnu informaciju o osnovnom i višim<br />harmonicima samo ako su njihove učestanosti ceolobrojni<br />umnožak učestanosti osnovnog harmonika. U slučaju pojave<br />interharmonika, odnosno kada taj odnos više ne važi,<br />hibridni metod ne daje tačne rezultate. Za analizu takvih<br />signala predložen je novi metod, koji je baziran na<br />adaptivnom diskretnom pojasnom filteru (ANF) t.j. metod<br />koristi diskretni pojasni filter za modelovanje<br />harmonijskih komponenata u ulaznom signalu, dok se<br />prošireni Kalmanov filter (EKF) koristi kao adaptivni<br />mehanizam. Novi metod je preuzeo osobinu ANF-a da može<br />adaptivno da prati promene učestanosti i osobinu EKF-a<br />da ima bolji dinamički odziv. Metode su implementirane<br />na digitalnom procesoru za obradu signala i upoređene sa<br />postojećim metodama. Metode pokazuju prednosti u odnosu<br />na druge metode.</p> / <p>Scientific research in this thesis discusses power quality<br />analysis. High power quality assumes that both the voltage<br />power supply and the load current are ideal sinusoidal signals<br />with a precisely defined amplitude and frequency. Any<br />deviations from this ideal vaweform are considered as distortion<br />and are characterised by harmonics.<br />Over the last few decades, there has been a rapid development<br />of semiconductor components. Such components made an<br />impact on the fast development of power electronics devices.<br />These devices are nonlinear, introducing harmonics in both<br />voltage and current of the power grid. The first issue researched<br />in this thesis is the analysis of the rectifier voltage and current<br />waveforms. Methods used for the analysis are the wavelet<br />transform (WT) and the modulated overlapped transform (MLT).<br />The MLT overcomes the drawback of the WT, which<br />decomposes the signal into subbands that can contain more<br />harmonics, and gives accurate information about every<br />harmonic. Both methods are suitable for offline analysis. For<br />online analysis, a hybrid method is proposed, based on the<br />discrete Fourier transform (DFT) and the adaptive notch filter<br />(EPLL). The hybrid method retains a good dynamic response of<br />the DFT whereas the EPLL provides a synchronisation with the<br />fundamental system frequency. The hybrid method provides<br />accurate information on the fundamental and the higher<br />harmonics only if their frequencies are integer multiples of the<br />fundamental frequency. In the case of interharmonics, i.e. when<br />this integer ratio is not valid, the hybrid method does not provide<br />accurate results. In order to analyse such signals, a new<br />method is proposed. It is based on discrete adaptive notch filter<br />(ANF), i.e. the method uses a discrete notch filter for modeling<br />the harmonic components in the input signal, whereas an<br />Extended Kalman Filter (EKF) is used as an adaptation<br />algorithm. The adaptive notch Kalman filter inherited the<br />property of the ANF to adaptively track changes in the<br />frequency and the property of the EKF to have a faster dynamic<br />response. Methods have been implemented in a digital signal<br />processor and compared with the existing ones. The methods<br />show advantages compared to other methods.</p>
| Identifer | oai:union.ndltd.org:uns.ac.rs/oai:CRISUNS:(BISIS)100921 |
| Date | 16 September 2016 |
| Creators | Knežević Jovan |
| Contributors | Katić Vladimir, Milanović Jovica, Dujić Dražen, Vasić Veran, Strezoski Vladimir |
| Publisher | Univerzitet u Novom Sadu, Fakultet tehničkih nauka u Novom Sadu, University of Novi Sad, Faculty of Technical Sciences at Novi Sad |
| Source Sets | University of Novi Sad |
| Language | Serbian |
| Detected Language | English |
| Type | PhD thesis |
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