Utilising the latent power is not the final solution as load demands on most secondary substation will continue to grow and, as EV update will increase dramatically at the same time, there will come a point when the latent energy is reduced or eliminated. In the future, secondary substation may be designed with additional capacity so a DC ring could be provided to utilise the latent power. More distributed energy resources such as solar PV or wind may be connected to the grid in the future, these could be used to supplement a DC ring with additional power. As distributed energy resources already generate DC current direct connections to a DC ring would be simplified and losses reduced. It may also be possible to integrate Battery Energy Storage Systems to store surplus DC power generated by DER for use when EV owners wish to rapid charge.
How will DC Share aid EV charging in the future?
How much structural change is needed to implement the DC Share scheme?
Changes to the existing infrastructure will essentially be zero as only new equipment will be installed. The new equipment includes AC/DC Grid Tied Invertors (GTI's), DC circuit breakers and isolators, cabling, AC/DC converters within the EV charging points and a SMART control and communications system to monitor and control the entire installation.
How does DC Share lead to fewer wasted assets?
It is possible that load on some secondary substations decreases over time (e.g. if a industrial plant closes), in this case the ‘assets’ at the secondary substation may become under-utilised (or "stranded"). Identifying such substations and including them within a DC ring would ensure all assets were utilised with maximum effect and the available power directed to where it is needed most.
What are the financial benefits of the DC Share project?
The electrical demand from rapid chargers is expected to rapidly grow with the inevitable uptake of EVs over the next decade, putting an enormous strain on the electrical grid. DC Share utilises existing electrical capacity in the network more effectively, meaning that future network enforcement costs can be avoided or deferred. In addition, there is an environmental benefit obtained due to encouraging the large-scale uptake of EVs.
In summary, it is anticipated that the DC Share project will provide the following benefits:
- £162m Net Present Value of financial benefits to 2050
- 1,800 MVA of capacity benefits
- 26,000 tCO2 equivalent of carbon emission reduction
What is the advantage of a DC system for EV charging?
One main advantage is associated with system losses. Using a DC over an AC connection means that the charge points can utilise a higher voltage (in out case 800VDC), meaning that current drawn is lower than if the same was fed from a 415VAC or 240VAC supply, resulting in significantly lower losses (I2R) wihtin the ring. As we are also able to connect the EV directly at DC (with no AC/DC conversion) then the losses at the interface point are also reduced. This means that more of the avaliable power can be used to provide EV charging and not wasted.
What makes DC Share effective for managing the electrical demand with the uptake of EVs?
One main criteria for encouraging the large-scale uptake of EVs is to ensure that EV owners can charge their vehicles to a satisfactory level within a few minutes – similar to ‘filling-up’ at a petrol station. To do this requires much larger ‘plug-in’ power availability than a traditional AC fed trickle charger (mainly for home use). To provide such an increase in power will put a large strain on the existing infrastructure if such connections are made directly to a secondary substation. By using the latent energy in the grid, converting it to DC and sharing it amongst secondary substations in the same geographical area will put less of a strain on the grid when latent energy is available and numerous rapid EV chargers are connected.