LV & 11kV Networks
Efforts to decarbonise energy generation and heat and transport will place increasing demands on distribution networks, particularly so for the low voltage (LV) networks closest to our customers, where DNOs have the obligation of supplying customers their electricity demand, within tightly defined voltage limits which their consumer electronics have been designed to expect, and at a sufficient quality (harmonics, sags, swells and flicker). Analysis carried out by Imperial College to support our RIIO-ED1 business plan predicted an increasing trend of voltage issues and demand rises that could overload transformers and underground cables, requiring £132.6m of network reinforcement during the RIIO-ED1 period if reinforced by conventional means.
Meshed networks offer one potential part of the answer. In meshed networks, customers are supplied by two or more different routes through the LV network, with the result that their demand can be shared across substations reducing heavily loaded transformers, voltage fluctuations tend to be suppressed, losses are reduced, and customers benefit from in-built resilience to high voltage (HV) network faults. The Smart Grid Forum identified meshed networks as a significant component of a smart network. UK Power Networks has run some parts of its networks meshed for many years. In urban and central business districts, there is potential for further meshing.
Power electronics devices will be used for the first time, in combination with remote configuration and informational tools, to access latent/spare capacity that already exists, in shorter timescales than conventional reinforcement. This solution allows a faster response to LV demand changes and higher utilisation of existing assets. Should reinforcement be required in the future, the equipment can be redeployed. The increased visibility will also aid the effectiveness of network planning. The project is expected to demonstrate headline savings of £2.36m across 36 trial sites, whilst importantly providing greater flexibility, faster connections and reducing the risk of long interruptions due to HV faults. We estimate that these can scale up to a saving of £112.8m on a rigorous discounted cashflow basis releasing up to 162 MW in shared capacity in the latter half of ED1 and ED2 across the whole of GB.