Solid-state circuit breakers (SSCB) show great promise to become the key element in the protection of low-voltage direct current microgrids. SSCBs operate in the microsecond range and employ semi-conductor devices that have strict safe operation area limits. Therefore, the design of the SSCB needs to consider the effects of fault detection delays and semi-conductor safe operation area limitations. This paper derives SSCB design criteria that consider the effect of different detection methods with different detection delays under varying system constraints. The design space is investigated in a sensitivity analysis, which provides insights into the operation boundaries of SSCB and explains how a combination of fault detection methods can reduce the SSCB size. The insights from the theoretical and sensitivity analysis are used to propose an SSCB design flowchart. SSCB prototype is developed and tested in different scenarios under nominal grid voltage and current. The derived design constraints can be used for efficient SSCB design and also to evaluate the effects of different protection schemes on the required SSCB size.
The number of electric vehicles in the Netherlands has sharply increased over the past decade. This has caused a need for the allocation of a substantial amount of new electric vehicle chargers around the country, which in turn has been acknowledged by a variety of legislative bodies. However, the approach of how these new charging infrastructures need to be spatially distributed has yet to be decided, including the distance that an electric vehicle charger could be allocated from the final destination of its driver. The hypothesis of this study is that if residents walk a longer distance to/from these charging stations, the chargers could be shared by a greater number of electric vehicle owners, and the total cost of the new charging infrastructure could be reduced. By using linear integer programming, the minimum cost of allocating new fastcharging stations in a central, densely populated area of Amsterdam, accounting for 7% of the city's population, is calculated. The results show that if residents were to walk for five minutes (roughly 400 metres) instead of two and half minutes (roughly 200 metres), the overall cost of new electric vehicle chargers could be reduced by more than 1 million euros. The study also found that both the cost of new charging stations and their efficiency of use are vastly affected by the portion of the charging infrastructure that is saved for people visiting the area. The findings of this study are discussed in detail, including the proposal of potential further studies.
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