This paper presents the technology and testing platform for interoperable e-mobility, infrastructure and power grids at TU Dortmund University. That environment allows to emulate several power grid states and to analyse the behaviour of charging station and EV regarding to both electrical and ICT aspects. Using this technology platform we developed an alternative method for Residual Current Detection with DC components in electrical vehicle charging. Standard methods are not very well suited for these requirements, because they are very expensive and need a manual reset. The method which is presented in this paper detects the fault current by using an AC/DC summation current transformer in the electric vehicle. The fault current is announced by a fault state. A control unit in the charging station detects the fault state which is transmitted by using the control pilot. The cut-off is done by the already existing charging contactor which is included in the charging station. The fault state is transmitted by using the control pilot. The here presented protection method has a comparable security level to typically used protection devices. It allows cost savings by a factor up to 50. It can be used also for cut-off by detecting an isolation failure.
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