Across the GB grid, more power is being contributed by wind turbines, solar farms and HVDC links, and this increase is expected to continue as we transition to a zero-carbon energy system. At present, all of these power sources use grid-following converters. The original DETECTS project confirmed that the proliferation of grid-following converters in the South East Coast part of the GB grid, revealed limitations in the ESO’s existing software tools to calculate accurate stability limits. The ESO requires a suitable method for calculating stability limits to ensure security of power supplies from the grid is to be maintained.
Benefits
As the level of grid-following converter use continues to grow, the risk of instability will also rise. Without an accurate indication of the level of instability, the risk of serious system disturbances occurring increases, which could also have significant economic impact. Understanding the new stability risks and when they occur will enable the system to be operated more efficiently by avoiding unnecessary constraints.
The benefits to consumers include reliable electricity supplies (avoiding the severe financial costs that would be associated with a major blackout), lower electricity wholesale costs (through avoiding unnecessary restrictions on the deployment or use of wind and solar, the lowest-cost sources of energy), and lower transmission tariffs (through avoidance of unnecessary investments to improve stability).
Learnings
Outcomes
The project has equipped the ESO with advanced tools to assess grid stability, particularly in the South East Coast, under minimal or no fossil-fueled generation conditions, which will become common from 2025 onwards.
Key outputs include the delivery of the PSCAD GB Grid model and a suite of Python scripts. The PSCAD model provides a detailed representation of the GB grid, incorporating essential "black box" models for components like HVDC systems, offshore wind farms, and STATCOMs. The Python scripts automate simulation processes, enhancing the ability to perform comprehensive and efficient analysis.
ESO personnel received thorough training in model development and Python-based simulations, ensuring they can independently conduct detailed electromagnetic transient (EMT) studies. This training enables ESO to evaluate the stability of the South East Coast area under various operating conditions, including high renewable penetration and low inertia scenarios.
These tools and training allow ESO to perform precise stability assessments, predict grid responses to disturbances, and optimize operations to maintain reliability. As the energy landscape shifts towards renewable sources, the PSCAD model and Python scripts are now crucial for ESO to manage this transition effectively.
Lessons Learnt
The inability to port at least one manufacturer-provided ("black box") model from one version of PSCAD to another highlights a significant issue. This discrepancy underscores the tension between the rapid evolution of computers and simulation software and the expectation that manufacturer-provided models should remain usable for the lifespan of the underlying asset, which can span several decades. Future projects with Transmission Excellence will aim to address this challenge.
Moreover, the training requirements for this project were more extensive than anticipated, necessitating four sessions of approximately four hours each. This experience demonstrates that future projects should not underestimate the complexity of EMT models, and the substantial time required to thoroughly discuss and communicate the numerous features inherent to such models.
