Feb 2018
Electricity Distribution and Electricity Transmission
LV Engine
SPMWEN02
Live
Feb 2018
Dec 2022
SP Distribution, SP Manweb and UK Power Networks
SPEN Innovation Team
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Network Innovation Competition
None
Carbon Emission Reduction Technologies, Electric Vehicles, Low Carbon Generation and LV & 11kV Networks
£6,900,000.00
The integration of low carbon technologies (LCTs) is creating a strain on LV networks. Consequently, there is a need to make a significant change in the way LV networks are planned and operated. Passive LV networks with limited flexibility may not deliver value for money for our customers in a low carbon energy system.
Project LV Engine aims to add flexibility to LV networks by informing the design and selection of intelligent secondary transformers to enable the cost effective uptake of LCTs. It will achieve this objective by carrying out a live network trial of two innovative technologies;
  1. Solid State Transformers (SSTs) as a direct replacement and;
  2. Vacuum Tap Changers as a retrofit option to the conventional secondary transformer (11kV/415V).
This trial will provide the LV network with the flexibility it requires to accommodate future uncertainties in the uptake of LCTs and customer behaviours. LV Engine will demonstrate the first grid trial of SSTs within the UK electricity network and provide valuable learning to other UK DNOs. The project will also make an LV DC supply available to customers to satisfy the increasing demand for Direct Current.
In order to develop a novel and informed approach to the selection of secondary transformers, we propose trialling smart Solid State Transformer (SSTs) within secondary substations and comparing their effectiveness in supporting the LV network with that of conventional MV/LV transformers retrofitted with vacuum tap changers. The trial will lead to policy documents, design tools, technical specifications and a methodology which will inform the optimal selection of the secondary transformers given the specific characteristics of the local LV networks.
This project will trial intelligent transformers for three distinctive applications where potential trial areas have already been investigated.
Application 1 – SST for Voltage Regulation & Power Quality
We have identified potential trial areas where the uptake of PV has been severely limited due to the capacity of the LV network to accommodate further generation without significant network reinforcement. Some of these LV networks supply tower social houses with PV fitted to address fuel poverty.

Application 2 – Vacuum Tap Changer for Voltage Regulation
It is expected that under certain network conditions SSTs may not be the most cost effective solution to reinforce the LV network where the penetration of LCTs is less severe. For this reason, the project will also trial vacuum tap changers as an alternative method of voltage regulation.
Application 3 – SST for LV DC
SSTs are capable of providing a LV DC supply to
satisfy the increasing DC requirements of our customers and reduce network losses. We intend to inform the future DC micro grid by trailing a DC supply for the connection of LCTs, EV charging stations, and large commercial customers. LV DC can also provide a DC link between two secondary substations to add power flow control functionality. This allows load balancing between secondary substations, additional network flexibility, and better utilisation of network assets.
We will use the learning from the aforementioned applications to inform the future selection of the most techno-economical technology given the characteristics of local LV network, reducing costly network reinforcement and delivering value for money to our customers.