Project Summary

The D-Suite beta phase meets three of Ofgem’s SIF Round Two Innovation Challenges: Preparing for a net zero power system; Improving energy system resilience and robustness; and Accelerating decarbonisation of major energy demands. It will be achieved by developing partially rated power‑electronic devices (D‑STATCOM, D‑SOP, D‑ST) integrated with a production‑grade LV Design Tool and Network Level Control System (NLCS) that together aims to address the growing challenges in low voltage (LV) electricity distribution networks caused by the rapid uptake of decarbonisation technologies such as EVs, heat pumps and distributed generation.

LV networks are increasingly experiencing voltage excursions, high transformer utilisation and severe phase imbalances. Traditional reinforcement approaches are often costly and disruptive. D-Suite seeks to develop and trial partially rated LV PEDs that offer a flexible, cost-effective alternative to conventional reinforcement.

The project is developing three core PED technologies as follows:

• Distribution Smart Transformer (D-ST) which is based on Unified Power Flow Controller (UPFC) architecture. The target Core Services of this device includes Voltage control per phase at the outgoing terminal, imbalanced load cancellation to reduce phase current imbalance seen upstream and controlled power flow to share capacity between neighbouring substations.
• Distribution STATCOM (D-STATCOM) which is a shunt-connected device for reactive power compensation and phase voltage balancing. The expected Core Services include voltage control per phase at the point of connection, power factor correction by regulating reactive power to reduce upstream flows/losses, imbalanced load cancellation to improve asset utilisation and phase voltage profiles.
• Distribution Soft Open Point (D-SOP) which is a back-to-back AC/DC/AC converter for dynamic feeder interconnection and bidirectional power flow control. The expected Core Services include controlled active/reactive power flow between two LV networks via back‑to‑back conversion, voltage control per phase through reactive power injection/absorption, imbalanced load cancellation ensuring no imbalance is transferred between the two interconnected substations.

These devices are supported by an operational LV Design Tool, developed by Newcastle University, which enables optimal siting and sizing of PEDs based on network constraints, technical benefits and cost effectiveness.

Innovation Justification

The D‑Suite project demonstrates novel and ambitious energy network innovation by introducing a fundamentally new approach to managing low‑voltage (LV) network constraints. Rather than relying on traditional reinforcement, which is costly and disruptive, D‑Suite deploys advanced Power Electronic Devices (PEDs), including D‑STATCOM, D‑SOP and D‑ST, combined with a production‑grade LV Design Tool and Network Level Control System (NLCS). This integrated solution actively controls voltage, phase imbalance and power flow in real time, enabling flexible, cost‑effective reinforcement deferral and accelerating the connection of low carbon technologies (LCTs) such as EVs and heat pumps.

The project builds directly upon the SIF Alpha Phase by addressing gaps identified during early prototyping and stakeholder engagement. In Alpha, the concept of PED deployment and optioneering was validated at a high level.

Beta advances this by:

• Developing and validating a five‑step siting and sizing algorithm within the LV Design Tool, integrated with SPEN’s NAVI platform for real‑time data access.
• Progressing modular PED hardware design and laboratory prototyping to de‑risk full‑scale trials.
• Establishing a network‑level control philosophy and I/O schedule to enable coordinated operation of multiple PEDs.
• Refreshing trial site selection and preparing detailed technical specifications for procurement.

These activities represent a step‑change from Alpha, moving from conceptual modelling to production‑grade tools and hardware ready for live trials.

The project is suitable for SIF funding rather than business‑as‑usual or other sources because it entails significant technical, operational and commercial risk. PEDs have not been deployed at scale on GB LV networks and their performance under real‑world conditions, including fault scenarios and communication loss, remains unproven. Similarly, the LV Design Tool introduces new algorithms and integration requirements that require rigorous validation before adoption. These uncertainties make the project inappropriate for standard investment mechanisms, but ideal for SIF’s innovation framework, which supports high‑risk, high‑reward demonstrations aligned with Ofgem’s Net Zero objectives.

Progression into the Beta Phase is justified by the strong foundations laid in Alpha and the clear need for further development to achieve readiness for Business as Usual (BaU). Beta will deliver tangible outputs, validated PED hardware, a fully functional LV Design Tool and trial evidence, that enable DNOs to adopt these innovations confidently. The project aligns with three SIF Round Two challenges which are preparing for a net zero power system, improving system resilience and accelerating decarbonisation of major energy demands. Its scale, ambition and replicability across GB networks underscore its suitability for continued SIF support.

Impacts and Benefits

A. Current Position (Pre‑Innovation Baseline) and Metrics
LV networks are increasingly constrained due to the rapid uptake of low carbon technologies (LCTs) such as EVs, heat pumps and distributed generation. Traditional reinforcement is the default solution, involving costly upgrades to cables and transformers, typically £50,000–£100,000 per feeder. This approach is disruptive, slow to deliver and lacks flexibility.

Baseline metrics include:

1. Voltage compliance which is the number of feeders exceeding statutory voltage limit
2. Phase imbalance which is measured in amperes across phases
3. Transformer utilisation which is the percentage loading relative to nameplate rating
4. Customer interruptions (CI) and minutes lost (CML) which are reliability indicators
5. Reinforcement costs which is the average cost per LV feeder upgrade

B. Forecast of Cumulative Net Benefits to Energy Consumers (Network Partner Level)
If implemented into Business as Usual (BaU), D‑Suite offers significant financial, environmental and societal benefits:

1. Financial benefits by avoided reinforcement costs estimated at £2m direct savings for SPEN, with whole‑life Net Present Value (NPV) of £98.38m for SPEN and £795.4m GB‑wide, best‑case exceeding £5.8bn.
2. Environmental benefits which are reduced carbon emissions through accelerated LCT adoption and deferred reinforcement works (estimated £24m environmental benefit for SPEN).
3. Societal benefits which are improved reliability and reduced disruption, supporting vulnerable customers and enabling equitable access to decarbonisation technologies (estimated £40m societal benefit for SPEN). Metrics for benefits include avoided reinforcement expenditure, NPV calculations, reduction in CI/CML and increased hosting capacity for EVs and heat pumps.

C. Benefits Already Realised Through Project Delivery
During the Beta Phase, the project has delivered early benefits:

1. Technical validation of the LV Design Tool against SPEN PowerFactory models, ensuring accuracy and readiness for BaU integration.
2. Supply chain engagement and manufacturer shortlisting, reducing procurement risk and accelerating readiness for commercialisation.
3. Knowledge dissemination through CIRED, CIGRE and ENA forums, improving industry awareness and capability.
4. Risk mitigation via modular PED prototypes and simulation models, de‑risking future trials and reducing programme uncertainty.

D. Other Impacts and Benefits Beyond Selected Categories
Over and above financial and technical benefits, D‑Suite delivers:

1. Social benefits which are enhanced reliability for vulnerable customers by reducing voltage excursions and phase imbalance, particularly in areas with high medical equipment reliance or poor insulation.
2. Environmental benefits which are Supports Net Zero by enabling faster, cost‑effective LCT connections without reinforcement, reducing carbon footprint of network upgrades.
3. Energy system resilience as benefit, PEDs provide dynamic voltage and power flow control, improving LV network robustness under high demand and generation variability.
4. Knowledge creation benfit through Open‑source LV Design Tool reference version and trial learnings will accelerate innovation adoption across GB networks.