The LCT Harmonic Limits project will undertake desktop research and investigate how many Electric Vehicles (EVs) and Heat Pumps (HPs) can be connected to an LV network prior to harmonic violations being exceeded. This project will model both urban and rural networks, consider the background emissions that are already in existence and also consider varying diversities of LCTs in terms of percentage of EV against HP and also the distribution of LCTs along a given feeder. 

The outcome of the project will aim to enhance our current design processes and standard techniques that focus on the minimum and maximum source impedance requirements before intervention is needed. Updating these standards will give greater confidence in our network and also result in quicker connections to customers.

Benefits

It is common knowledge that we foresee a significant increase in LCT connections surrounding EVs, HPs and BESS within this time period and in doing so, due to the harmonic output that they provide, they may require some form of harmonic assessment from NGED prior to the network being confident the connecting asset will not cause non-conforming issues.

Carrying out these assessments can be a time consuming process, and having a process that allows these assessments to be reduced will inevitably increase staff cost savings. The following page highlights the high level assumptions and information used to inform the potential financial benefits LCT harmonic Limits will bring.

These assumptions are:

• The number of NGED Pole Mounted Transformers (PMT) is 58,000
• The number of NGED Ground Mounted Transformers (GMT) is 127,000
• Harmonic assessment is needed for at least 50% of these sites
• Time take for harmonic assessment is between ½ day to 1 day
• Day rate for assessment is network service day rate of £445
• Assume inflation rate for assessment of 2.5%
• LCT Harmonic Limits process allows 35% reduction of assessments

Spreading out the total number of sites (185,000) over a 16 year period (2024-2040, End of ED4) results in a total number of 11,562 assessments needed to be carried out per year out to the end of RIIO-ED4 (not including additional PMT and GMT that will exist in that time period). As stated in the assumptions, a conservative minimum 50% of sites will need some form of harmonic assessment with the taken for between ½ day and 1 day. The bullet points below outlines the labour cost to carry out assessment based on number of sites and duration it takes. 

• 50% of sites, ½ day assessment (£1.29m / year)
• 80% of sites, ½ day assessment (£2.06 / year)
• 100% of sites, ½ day assessment (£2.57m / year
• 50% of sites, 1 day assessment (£2.57m / year)
• 80% of sites, 1 day assessment (£4.12m / year)
• 100% of sites, 1 day assessment (£5.15m / year)

Based of the above calculations, the below table highlights the baseline costs assessments have to NGED out to the end of the ED4 price control period (2040). 

• 50% of sites, ½ day assessment yielding a summated cost of £26.8m out until 2040
• 80% of sites, ½ day assessment yielding a summated cost of £42.9m out until 2040
• 50% of sites, 1 day assessment yielding a summated cost of £53.7m out until 2040

Having established the baseline figures, it is worthwhile understanding the proposed counterfactual in order to understand the underlying benefits the LCT Harmonic limits project brings. The assumption is that with the LCT Harmonics process in place, the reduction of assessments carried out will be 35% less than the base case. Applying this information to the calculations above, it yields updating costings that will be spent by NGED on carrying out harmonic assessments.

• 50% of sites, ½ day assessment  yielding a summated cost of £17.4m out until 2040
• 80% of sites, ½ day assessment  yielding a summated cost of £27.9m out until 2040
• 50% of sites, 1 day assessment yielding a summated cost of £34.9m out until 2040

Annually, the benefits are estimated to be between £390k-£790k, over the ED2 period between £1.56m-£3.15m and out to 2040, between £6.30m-£12.6m.