Due to global warming, air pollution, makes the world to think of a different way of transportation, avoiding IC (Internal Combustion) vehicles and replacing them with electrical ones. These recent concerns about the impact of air pollution on our planet are the main stigma for the initialization of the electrification of the transportation sector. With the starting of the deployment of electric vehicles (EVs) on the market, the impact of EV charging stations loads on the operating parameters of the power system has been noticed. The considerable impact of EV charging station loads on the electricity distribution network cannot be neglected and needs careful attention. With a high penetration of EV charging stations on an existing power distribution network, the impact is higher. The greater the penetration level, the higher the impact on the power grid. The high charging loads of the fast-charging stations results in increased peak load demand, reduced reserve margins, voltage instability, and reliability problems. The degrading performance of the power system due to the negative impact of the EV charging stations can lead to a penalty to be paid by the utility. This thesis aims to investigate the impact of the EV charging station loads on the distribution network congestion like voltage drop, power loading of power system elements, and reliability indices of a power distribution network around Milan, Italy. Furthermore, the study is aimed to be a reference guide for the major Italian distribution system operator (DSO), e-distribuzione, to anticipate the impact its distribution system could face once the penetration level of EV charging station load starts to grow. The analysis was performed on a representation of a real power grid near Milan metropolitan city. The study is conducted on four cases, with different scenarios inside. The different scenarios within the cases include, different EV load penetration percentages, different load growth for different years, loads on the summer and winter. In order the see the characteristics of the distribution network tools like, peak to average ratio of power (PAR), peak power, minimum loading, maximum loading, maximum voltage deviation, are used. The data analyzed and the graph of the simulations are distributed for every 15 minutes in a 24 hours range. It was seen that the power system elements, like the main transformer and distribution lines, will be loaded during peak hours. Regarding the voltage drop, the distribution network is within acceptable limits even if on the high EV charging load penetration time. The voltage at the main substation reaches 1.0 pu in the worst scenario, in which some voltage drop below the limit at the farthest node of the network is anticipated. The power grid was built in DIgSILENT Power Factory and the same software has been used to perform the power flow calculations. MATLAB was used for some calculations and visualizing the result obtained. Finally, to mitigate the distribution network congestion, load optimization and operation policies are discussed.
A causa del riscaldamento globale, l’inquinamento atmosferico induce il mondo a pensare a un diverso paradigma per il trasporto: evitare i veicoli a combustione interna (IC) e sostituirli con veicoli elettrici (EV). Queste recenti preoccupazioni sull’impatto dell’inquinamento atmosferico sul nostro pianeta sono la ragione principale per l’avvio dell’elettrificazione del settore dei trasporti su gomma. Con la diffusione di veicoli elettrici sul mercato, è stato notato che le stazioni di ricarica dei veicoli elettrici possono avere impatti consistenti sui parametri operativi del sistema di distribuzione. Il notevole impatto dei carichi delle stazioni di ricarica sulla rete di distribuzione non può essere trascurato e richiede attenzione. Con un’alta penetrazione delle stazioni di ricarica l’impatto è sicuramente maggiore. Gli elevati carichi delle stazioni di ricarica rapida comportano un aumento della richiesta di carico nel picco, una riduzione dei margini di riserva, l’instabilità della tensione e altri problemi di affidabilità. Le prestazioni degradanti del sistema di alimentazione dovute all’impatto negativo delle stazioni di ricarica per veicoli elettrici possono comportare anche sanzione a carico dei distributori. Questa tesi mira a studiare l’impatto delle stazioni di ricarica sulle reti di distribuzione come, ad esempio, la caduta di tensione, il sovraccarico degli elementi del sistema e gli indici di affidabilità . Inoltre, lo studio ha lo scopo di essere una guida di riferimento per il principale distributore italiano, e-distribuzione, per prevedere l’impatto che il suo sistema di distribuzione potrebbe subire una volta che il livello di penetrazione delle stazioni di ricarica dovesse iniziare a crescere. L’analisi è stata effettuata su una vera rete elettrica vicino alla città metropolitana di Milano. Lo studio è condotto su quattro casi, con diversi scenari all’interno che includono: diverse percentuali di penetrazione deli veicoli elettrici, diversi tassi di crescita del carico, differenziazione dei carichi in estate e in inverno. Per valutare gli effetti sugli strumenti della rete di distribuzione sono stati utilizzati indici quali il rapporto picco-potenza medio, la potenza di picco, il carico minimo, il carico massimo, e la deviazione massima di tensione. Si è visto che gli elementi del sistema di distribuzione, come il trasformatore di cabina primaria e le linee di distribuzione, verranno sovraccaricati nelle ore di punta. Per quanto riguarda la caduta di tensione, la rete di distribuzione rientra nei limiti accettabili anche per elevate percentuali di penetrazione dei veicoli elettrici. La tensione nella cabina primaria raggiunge 1,0 pu nello scenario peggiore, in cui è prevista una caduta di tensione al di sotto del limite nel nodo più lontano della rete. La rete elettrica è stata costruita utilizzando DIgSILENT Power Factory. Il medesimo software è stato utilizzato per eseguire i calcoli del power flow. MATLAB è stato utilizzato per alcuni calcoli accessori e per visualizzare i risultati ottenuti. Infine, per mitigare la congestione della rete di distribuzione, vengono discusse l’ottimizzazione del carico e l’introduzione di alcune politiche di gestione operativa.
Impact of EV charging stations in power grids in Italy and its mitigation mechanisms
SAMSON MOGOS, AMAN
2019/2020
Abstract
Due to global warming, air pollution, makes the world to think of a different way of transportation, avoiding IC (Internal Combustion) vehicles and replacing them with electrical ones. These recent concerns about the impact of air pollution on our planet are the main stigma for the initialization of the electrification of the transportation sector. With the starting of the deployment of electric vehicles (EVs) on the market, the impact of EV charging stations loads on the operating parameters of the power system has been noticed. The considerable impact of EV charging station loads on the electricity distribution network cannot be neglected and needs careful attention. With a high penetration of EV charging stations on an existing power distribution network, the impact is higher. The greater the penetration level, the higher the impact on the power grid. The high charging loads of the fast-charging stations results in increased peak load demand, reduced reserve margins, voltage instability, and reliability problems. The degrading performance of the power system due to the negative impact of the EV charging stations can lead to a penalty to be paid by the utility. This thesis aims to investigate the impact of the EV charging station loads on the distribution network congestion like voltage drop, power loading of power system elements, and reliability indices of a power distribution network around Milan, Italy. Furthermore, the study is aimed to be a reference guide for the major Italian distribution system operator (DSO), e-distribuzione, to anticipate the impact its distribution system could face once the penetration level of EV charging station load starts to grow. The analysis was performed on a representation of a real power grid near Milan metropolitan city. The study is conducted on four cases, with different scenarios inside. The different scenarios within the cases include, different EV load penetration percentages, different load growth for different years, loads on the summer and winter. In order the see the characteristics of the distribution network tools like, peak to average ratio of power (PAR), peak power, minimum loading, maximum loading, maximum voltage deviation, are used. The data analyzed and the graph of the simulations are distributed for every 15 minutes in a 24 hours range. It was seen that the power system elements, like the main transformer and distribution lines, will be loaded during peak hours. Regarding the voltage drop, the distribution network is within acceptable limits even if on the high EV charging load penetration time. The voltage at the main substation reaches 1.0 pu in the worst scenario, in which some voltage drop below the limit at the farthest node of the network is anticipated. The power grid was built in DIgSILENT Power Factory and the same software has been used to perform the power flow calculations. MATLAB was used for some calculations and visualizing the result obtained. Finally, to mitigate the distribution network congestion, load optimization and operation policies are discussed.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/164414