| dc.description.abstract | As part of reducing the emissions from personal transportation EV adoption is expected to rise
dramatically in the coming decade. Whilst this has a positive effect on climate targets issues the
current distribution networks for electricity were not built to accommodate the large rise in EV. This
problem can be tackled in a number of different ways, such as by expanding network capacity, or
including of storage at the distribution level. This thesis, however looks at price based incentives to
mitigate the adverse effects of EV charging on distribution grids. In particular a restructuring of
distribution grid tariffs was considered. Distribution grid tariffs are the tariffs paid by customers to
distribution system operators (DSOs) for use and maintenance of the grid. Currently most
customers connected to the low voltage distribution grid pay a flat rate for the grid tariffs. However,
by restructuring these grid tariffs incentives can be provided in order to make sure EVs use the
flexibility which exists in the charging sessions in order to limit congestion issues. In particular this
study will look at public charging, that is charging points (CPs) connected to the distribution network
and operated by a charging point operator (CPO).
Two particular proposals for grid tariff redesign were assessed. In the capacity subscription plus
model (CAP+) the customer chooses a subscribed capacity, that is a power up to which the customer
can freely use the grid. This subscribed capacity has options at a few different capacity sizes with
associated costs. When the customer exceeds the subscribed capacity an exceedance fee has to be
paid for each exceeded kilowatt-hour. The other considered option is a particular case of dynamic
grid tariffs where the CPO pays differing prices for power used at particular times. How much power
can be used at each time at the differing price levels is determined the day ahead. This tariff design
bundles all CPs connected to the same transformer, thus the total power is what matters rather than
the individual power of the CPs.
A perfect information model was constructed to find the optimal CPO behavior on a cost-wise basis
under the different tariff designs (current, dynamic and CAP+). It is evident from the results that if
the tariff design is left unchanged, and no alternative measures are taken to address the issue of
transformer overloading due to EV charging at public charging points, problems are likely to occur.
Introducing the CAP+ tariff design can mitigate part of this problem. But as the CAP+ tariff design
focusses on individual usage peaks rather than the collective network peak which causes this
transformer overloading it is not as effective at reducing transformer overloading as the Dynamic
tariffs can be.
For the implementation of a tariff design more factors need to be considered, however. The
regulatory authority (ACM) is responsible for accrediting a tariff design and considers factors such as
non-discrimination, simplicity, transparency and more. In this regard the dynamic tariffs are more
controversial as it requires technological capabilities and has a fairly complicated mechanic involving
predicted transformer loads. Whether the advantages of the dynamic tariff design in terms of
efficient network use, and thus overall costs reductions, outweigh the problems with current
legislation and these regulatory principles is, in the end, a decision to be made by the regulator and
is left outside the scope of this research. | |
