Nowadays environmental protection is a great aim in power industry. Energy saving and power quality become more and more important. On the other hand, the publicity of electric vehicles (EVs) causes impacts to the power system since the EV chargers are nonlinear devices and have high current demand. In order to reduce spinning reserve and make use of the power system more efficiently, a flat load profile with low maximum current demand is expected. However, low charging current and short charging time are contrary. To make a compromise, an idea of coordination of charging stations is proposed to reduce the current demand without elongating the charging time greatly. The coordination is achieved by a fuzzy controller that can determine an optimal charging current for each EV in the real time. The controller is designed in such a way that it can be used with existing ordinary chargers. Certainly, EV chargers are no longer to be considered separately. They are treated as a closed process since they are usually connected parallel and take power from a common bus. The controller should monitor not only a charger's internal conditions, but also the external environment. lt keeps track on the external total current demand, internal charging current and charging time to make a decision. Actually the coordination is a stochastic problem and the performance is evaluated by different approaches. The fuzzy rules are tuned to handle up to twelve EVs that start charging at any time instance with any state of charge (SOC) less than 50% of capacity. The results show how the chargers are adaptive to both internal and external changes. Comparing to a constant current charger with mean current output, chargers with coordination require a lower peak current demand.
Coordination of charging stations for electric vehicles
räumliche und betriebstechnische Anordnung von Ladestationen für Elektrofahrzeuge
1999
10 Seiten, 7 Bilder, 5 Tabellen, 5 Quellen
Aufsatz (Konferenz)
Englisch
Coordination of Charging Stations for Electric Vehicles
British Library Conference Proceedings | 1999
|Coordination of charging stations for electric vehicles
Kraftfahrwesen | 1999
|