SSEN Transmission optimises Outage Planning with N-SIDE

Summary

In this case study, you will discover details regarding:

• The current outage planning challenges for SSEN Transmission.
• The innovative Year-Ahead Outage Optimiser developed by N-SIDE, which utilises multi-objective optimisation and automatic validation.
• The advantages of implementing this tool. Preliminary results from the proof of concept demonstrate a potential 34% reduction in total outages and improved network availability.
• Finally, the conclusions drawn from the successful proof of concept and the 2026 roadmap.

Project Introduction

The project, funded through Ofgem’s Network Innovation Allowance (NIA), aims to introduce a data-driven approach to outage planning through strategic collaboration. For electricity transmission operators, outage planning is a complex puzzle of balancing network security, resource limits, and a high volume of work. Planners must constantly navigate these competing goals, often forcing difficult trade-offs between maximising work delivery and minimising network disruption. SSEN Transmission partnered with N-SIDE to develop a Year-Ahead Outage Optimiser tool to transform this manual process into a strategic advantage.

Outage Planning Validation: This feature automatically scans an outage plan to identify any “clashes” or violations of pre-defined operational rules.

Customer Challenge

The large-scale integration of renewable energy sources has exacerbated the volatility of SSEN Transmission’s outage planning. This intensifies the challenge of balancing competing goals, creating a complex, dynamic environment where planners must manually manage a high volume of changes. This results in a significant workload and slower, more reactive decision-making.

The Solution/Approach

To measure its impact, the outage planning tool was applied directly to SSEN Transmission’s historical data in a three-step process:

1. Automatic plan validation: First, the Outage Planning Validation module scans the existing benchmark plan. This module serves as a critical feasibility check for any schedule, automatically identifying “clashes” (violations of predefined operational and resource constraints) that are time-consuming to detect manually.
2. Multi-objective optimisation: Next, the core Outage Planning Optimisation engine is fed with the entire list of work requests. It uses its multi-objective function to generate a new, fully compliant schedule that balances competing goals: maximising delivered requests, minimising outages, and ensuring network stability.
3. Ad hoc change management: Finally, the Single Request Analysis feature demonstrates an automated workflow for managing ad hoc changes. This feature provides immediate decision support to planners, enabling them to find the optimal slot for a new request with minimal disruption.

Outage Planning Optimisation: This is the core engine of Year-Ahead Outage Optimiser. It takes a list of requests with original planned dates and generates a new, fully compliant, and optimised schedule.

Implementation

Beyond the core algorithm, the solution was designed as ready-to-use software specifically tailored to SSEN Transmission’s needs. It features a centralised interface that boosts collaboration and simplifies the planning validation process. The tool is designed to support decision-making rather than replace it, keeping planning engineers firmly in the driver’s seat.

Benefits

The proof of concept confirmed that the outage planning tool provided a robust, flexible solution that achieved preliminary success in key areas:

Strategic capabilities

The Year Ahead Outage Optimiser tool provides a critical safety and compliance net by automatically identifying violations in the benchmark plan, ensuring a feasible baseline for operations. The Flexible Optimisation feature, driven by its multi-objective function, empowers planners to customise the definition of an optimal plan, allowing them to weigh “maximum delivery” against “maximum network uptime”. Furthermore, it enhances schedule stability by minimising work shifting and reducing customer impact by prioritising preferred periods. 

The tool also enables strategic decision-making through a powerful “What-if” Sensitivity Analysis feature, allowing planners to run scenarios by adjusting constraints and priorities before implementation. Finally, for day-to-day operations, the tool provides a clear path to reduce the time and effort required to manage ad hoc changes.

Single Request Analysis: This module instantly finds the optimal, least disruptive slot for a request and explains planning constraints.

Conclusion

The proof-of-concept successfully concluded in November 2025, with a definitive result: the tool eliminates the compromise TSOs faced, proving that high work delivery and operational efficiency can be achieved. Based on these strong results, N-SIDE and SSEN Transmission are now evaluating a second phase for 2026 to move the tool forward, including further refinement, new operational features, and deeper system integration.