Nowadays, electrical networks are characterized by currents with a big harmonic content, due to the wide and rapid diffusion of nonlinear loads. The ability to monitor the harmonic components of grid currents is important, and for this reason new methods for the testing of transduscers in this scenario have to be researched. Scientific literature shows that the optimal methodology for the characterization of transducers used for harmonic measurements should be based on the injection of multitone waveforms, similar to those encountered in the grid. It should also be considered that current transducers are generally used for three-phase current measurements, and could be affected by nonlinearities and crosstalk caused by the interaction between different phases. For this reason, tests for the characterization of these current transducers should be carried out by injecting a real three-phase system of multitone currents, not by merely combining three single-phase tests. This type of testing requires the usage of a three-phase generator capable of supplying arbitrary currents, which is usually not available in electrical measurement laboratories, mainly due to its high cost. This thesis presents the analysis and implementation of a low cost three-wire, three-phase arbitrary waveform current generator, with a simple architecture that exploits equipment commonly present in every laboratory devoted to electrical measurements. Firstly, he structure of the generator will be presented, then the focus is moved to the modeling and characterization tecnique of the generator. In the end, the performance of the system will be evaluated, by the generation of multitone current triplets similar to the ones that can by found in the grid.
Oggi, le reti elettriche sono caratterizzate da correnti sempre più ricche di armoniche, a causa della larga e rapida diffusione di carichi distorcenti. Da un lato è importante essere in grado di monitorare le componenti armoniche presenti nelle correnti di rete, dall’altro si rende necessaria la ricerca di nuovi metodi per la caratterizzazione dei trasduttori in questo scenario. La letteratura scientifica mostra che il metodo ottimale per la caratterizzazione dei trasduttori utilizzati per la misura di componenti armoniche sia basato sull’iniezione di correnti multi-sinusoidali, simili a quelle realmente riscontrate nella rete. Bisogna anche considerare che i trasduttori di corrente sono generalmente utilizzati per misure trifase di corrente, con conseguente possibilità di effetti non lineari e diafonia causati dall’interazione tra fasi diverse. Per questo motivo, le prove per la caratterizzazione di trasduttori trifase di corrente dovrebbero essere basate sull’iniezione di un vero sistema trifase di correnti multi-sinusoidali, e non sulla mera combinazione di tre prove monofase. Questa tipologia di prova richiede quindi un generatore trifase che sia in grado di erogare correnti arbitrarie, generalmente non disponibile nei laboratori di misure elettriche principalmente a causa del suo elevato costo. Questa tesi riguarda l’analisi e l’implementazione di un generatore trifase di corrente a tre fili con forma d’onda arbitraria e a basso costo, caratterizzato da un’architettura semplice che sfrutta componenti generalmente presenti in tutti i laboratori di misure elettriche. Verrà approfondita la struttura del generatore, la sua modellizzazione e caratterizzazione, e infine verranno valutate le sue prestazioni nel generare delle terne di correnti multi sinusoidali simili a quelle realmente presenti nelle reti elettriche.
Generatore trifase di corrente con forma d'onda arbitraria e a basso costo
Demetrio, Adriano
2022/2023
Abstract
Nowadays, electrical networks are characterized by currents with a big harmonic content, due to the wide and rapid diffusion of nonlinear loads. The ability to monitor the harmonic components of grid currents is important, and for this reason new methods for the testing of transduscers in this scenario have to be researched. Scientific literature shows that the optimal methodology for the characterization of transducers used for harmonic measurements should be based on the injection of multitone waveforms, similar to those encountered in the grid. It should also be considered that current transducers are generally used for three-phase current measurements, and could be affected by nonlinearities and crosstalk caused by the interaction between different phases. For this reason, tests for the characterization of these current transducers should be carried out by injecting a real three-phase system of multitone currents, not by merely combining three single-phase tests. This type of testing requires the usage of a three-phase generator capable of supplying arbitrary currents, which is usually not available in electrical measurement laboratories, mainly due to its high cost. This thesis presents the analysis and implementation of a low cost three-wire, three-phase arbitrary waveform current generator, with a simple architecture that exploits equipment commonly present in every laboratory devoted to electrical measurements. Firstly, he structure of the generator will be presented, then the focus is moved to the modeling and characterization tecnique of the generator. In the end, the performance of the system will be evaluated, by the generation of multitone current triplets similar to the ones that can by found in the grid.File | Dimensione | Formato | |
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executive_summary_Adriano_Demetrio.pdf
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tesi_Adriano_Demetrio.pdf
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https://hdl.handle.net/10589/215289