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.