This project will use smart meter data to provide improved visibility of the existing capacity headroom along the length of feeders, and to improve the targeting in location and time of active and reactive power management of V2G, (also known as Volt/Var or Volt/Watt control techniques), while improving the confidence that assets will remain within thermal and voltage limits.
Benefits
The NGED SILVERSMITH NIA project assessed the impacts of LCTs on LV assets, proposing a series of archetype networks that were modelled to determine whether voltage or thermal constraints would apply, and how they might be mitigated if so. Uptake of LCTs was modelled based on NGED’s Distribution Future Energy Scenarios and included exports from solar PV and a limited number of battery storage installations, but not V2G. The export capacity from V2G is therefore additional to the capacity shown in these results.
The plot below shows a modified version of the timeline for the LV6 archetype, representing a typical suburban underground radial feeder serving domestic customers with 3- or 4- bedroom houses. The grey line shows predicted maximum export capacities form the LV feeder, and other dotted lines show how investments in the voltage rise and thermal loading capacity would be needed so that the predicted export can be accommodated. The line in red has been added to incorporate an uptake of V2G of up to 45% of customers based on figures from the National Grid ESO Future Energy Scenarios (‘Leading the Way’), with 33 customers on the LV feeder and with coordinated exports of 7 kW V2G chargers. This assumes no diversity in the V2G operation, which is plausible as a response to an aggregator request will tend to align these exports in time. The figures are also conservative as they also ignore the likely occurrent of clustering and the possibility that customers will have three-phase chargers. Exports including V2G now exceed the available voltage rise capacity much earlier (2028 rather than 2032) and also exceed the thermal constraints around 2037.
Taking this archetype as an example, the voltage rise investment of £9.5k per LV feeder would be brought forward by 4 years due to V2G. However, the peak exports causing this investment are likely to occur rarely, only when demand is low and both the PV and V2G exports occur simultaneously. The V2G dynamic headroom methods therefore avoid bringing forward this investment, while retaining the customer value of V2G exports for the majority of discharging events when not all exports occur at the same time.
Avoiding bringing this investment forward saves £368 per LV feeder, based on a £2,495 cost to provide the additional voltage rise capacity through manual tap changes, assuming a discount rate of 3.5% and time period of 4 years. If this avoided early investment applies to 10% of feeders, then there is a saving of £1.9m over the 54,064 feeders that this archetype represents.
Over the GB distribution system, this saving can approximately be scaled by the number of domestic households served, 28 million across GB compared to 8 million for NGED, suggesting a GB-wide saving of £6.6m. Clearly this estimate involves significant assumptions, but it is also conservative in as calculations here are only based on the LV6 archetype, covering 16% of the LV feeders in the NGED license, but the techniques could be applied throughout, wherever V2G customers are likely to occur. It has also been assumed that the savings only apply in 10% of feeders within one archetype but savings could also apply more widely, albeit at a later date.
There is a further risk that V2G would necessitate bringing forward the thermal capacity upgrades from 2037 to 2035. The V2G dynamic headroom can also mitigate this, although the thermal capacity upgrades would still be required in the longer term.
