Recently, with the increase in local energy generation from Renewable Energy Sources (RESs), the research focuses on developing and integrating RESs into conventional power systems. For this reason, to reduce operational costs and increase efficiency, the concept of smart grids has been introduced. As a result of the development of smart grids, integration of RESs at the distribution level along with local loads and possible energy storage is representing a new structure depicted as microgrids. Microgrids can be classified into Alternating Current (AC) and Direct current (DC) microgrids. Nowadays, the possibility of utilizing DC microgrids, specifically in low voltage levels, has gained huge research interest since it offers several advantages in power systems compared to AC networks such as reduction of power conversion stages which leads to improving efficiency. Consequently, by developing Low Voltage Direct Current (LVDC) distribution networks, essential power electronics and protection devices have recently been a research priority. Regardless of their significant benefits, implementing an efficient and cost-effective protection scheme for a DC system is still a major barrier to LVDC microgrids application. Hence, it is important to investigate the various forms of network configurations and faults that can arise and define how these systems behave in such conditions. This analysis will help to understand the system more precisely and lead to specify innovative over-currents and ground fault protection, since the traditional protections may not work correctly. In this project, we are going to study the different network configurations such as unipolar and bipolar structures for LVDC distribution systems and analyze the system behavior before the presence of a fault and also when different types of fault, such as short circuit and ground fault, are introduced. The behavior of the converter and network in the case of the presence of fault is finally compared with the normal operation mode and explained further.
Di recente, con l'aumento della produzione locale di energia da fonti di energia rinnovabile (RES), la ricerca si concentra sullo sviluppo e l'integrazione di RES nei sistemi energetici convenzionali. Per questo motivo, per ridurre i costi operativi e aumentare l'efficienza, è stato introdotto il concetto di smart grid. Come risultato dello sviluppo delle reti intelligenti, l'integrazione delle FER a livello di distribuzione insieme ai carichi locali e al possibile accumulo di energia sta rappresentando una nuova struttura rappresentata come microgrid. Le microgriglie possono essere classificate in microgriglie a corrente alternata (CA) e corrente continua (CC). Al giorno d'oggi, la possibilità di utilizzare microgrid CC, in particolare a livelli di bassa tensione, ha suscitato un enorme interesse nella ricerca poiché offre numerosi vantaggi nei sistemi di alimentazione rispetto alle reti CA come la riduzione degli stadi di conversione di potenza che porta a un miglioramento dell'efficienza. Di conseguenza, sviluppando reti di distribuzione a corrente continua a bassa tensione (LVDC), l'elettronica di potenza essenziale ei dispositivi di protezione sono stati recentemente una priorità della ricerca. Indipendentemente dai loro vantaggi significativi, l'implementazione di uno schema di protezione efficiente ed economicamente vantaggioso per un sistema DC è ancora un ostacolo importante all'applicazione delle microgrid LVDC. Pertanto, è importante studiare le varie forme di configurazioni di rete e guasti che possono sorgere e definire come questi sistemi si comportano in tali condizioni. Questa analisi aiuterà a comprendere il sistema in modo più preciso e porterà a specificare protezioni innovative per sovracorrenti e guasti a terra, poiché le protezioni tradizionali potrebbero non funzionare correttamente. In questo progetto studieremo le diverse configurazioni di rete come strutture unipolari e bipolari per sistemi di distribuzione LVDC e analizzeremo il comportamento del sistema prima della presenza di un guasto e anche quando diversi tipi di guasto, come cortocircuito e guasto verso terra, vengono introdotti. Il comportamento del convertitore e della rete in caso di presenza di guasto viene infine confrontato con la modalità di funzionamento normale e spiegato ulteriormente.
Fault analysis in an LVDC micro-grid with different configurations using front-end converter
Ashtari, Amirhossein
2020/2021
Abstract
Recently, with the increase in local energy generation from Renewable Energy Sources (RESs), the research focuses on developing and integrating RESs into conventional power systems. For this reason, to reduce operational costs and increase efficiency, the concept of smart grids has been introduced. As a result of the development of smart grids, integration of RESs at the distribution level along with local loads and possible energy storage is representing a new structure depicted as microgrids. Microgrids can be classified into Alternating Current (AC) and Direct current (DC) microgrids. Nowadays, the possibility of utilizing DC microgrids, specifically in low voltage levels, has gained huge research interest since it offers several advantages in power systems compared to AC networks such as reduction of power conversion stages which leads to improving efficiency. Consequently, by developing Low Voltage Direct Current (LVDC) distribution networks, essential power electronics and protection devices have recently been a research priority. Regardless of their significant benefits, implementing an efficient and cost-effective protection scheme for a DC system is still a major barrier to LVDC microgrids application. Hence, it is important to investigate the various forms of network configurations and faults that can arise and define how these systems behave in such conditions. This analysis will help to understand the system more precisely and lead to specify innovative over-currents and ground fault protection, since the traditional protections may not work correctly. In this project, we are going to study the different network configurations such as unipolar and bipolar structures for LVDC distribution systems and analyze the system behavior before the presence of a fault and also when different types of fault, such as short circuit and ground fault, are introduced. The behavior of the converter and network in the case of the presence of fault is finally compared with the normal operation mode and explained further.| File | Dimensione | Formato | |
|---|---|---|---|
|
Thesis report.pdf
accessibile in internet per tutti
Dimensione
13.67 MB
Formato
Adobe PDF
|
13.67 MB | Adobe PDF | Visualizza/Apri |
I documenti in POLITesi sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
https://hdl.handle.net/10589/188173