Italiano
‘Modern power station practice’, to those in the industry, refers to a set of printed textbooks found in power station libraries, design offices and control rooms across the country and anywhere else where British engineers were responsible for equipment. First published in 1963 by the Central Electricity Generating Board, it became the engineer’s bible for design, construction, operation and, pertinent to this discussion, maintenance of power stations.
Less has changed in the power industry since that time than outsiders might guess. During my decade working for a large power company, I frequently referenced documents from the 1960s and 1970s, as well as rules of thumb passed down from senior engineers. However, one notable exception can be found in the development and growth of the renewables sector, firstly with wind and more recently solar generation becoming an important contributor to the power system.
‘Conventional’ coal, gas and nuclear power stations are large and extremely expensive assets, usually designed (at least in part) by the eventual owner and operator. These companies are, if not still owned by the state, successors of nationalised industry with a large engineering support staff either supervising or conducting comprehensive maintenance regimes on their assets. Periods of maintenance lasting weeks or months are common, with hundreds of contractors on site during these activities. Detailed records are produced and reviewed by teams of expert engineers, allowing trends, predictions and comparative analysis to identify the best possible technical responses, with a recognition from the owner operators that keeping a complicated and expensive station running smoothly requires substantial investments and interruptions have serious consequences. The legacy and structure of the industry also allows engineering functions to hold significant sway in some of the decision-making processes. This does not always go as planned, with the loss of power to Heathrow Airport being a recent example of a critical asset falling through a maintenance record gap, but generally the conventional stations can be held up as examples of good practice
Maintenance in the Renewable Sector
Renewable generators do not always follow this format. Whilst the initial design and construction of installations is still done by large engineering companies with substantial expertise, the eventual owner is frequently a financial vehicle of some sort. These owners do not have large engineering departments, or sometimes no engineering function at all, and must, therefore, rely on others for technical services. This has led to a growth in independent Operations & Maintenance (O&M) providers who bid to provide the technical support required to keep the assets running.
In my experience, the usual bidding process involves the O&M company providing both the technical scope and the price for review by the owner. Perhaps due to the limited engineering expertise within the owners, there is a risk that the technical scope is not given sufficient weight, and that more limited maintenance scopes are selected because of their lower costs. This can also lead to the subcontracting of testing or inspection tasks to third parties. The relatively lower asset values of renewable generation sites when compared to conventional power stations tends to steer discussions away from what may be perceived as ‘overkill’ comprehensive approaches.
Example
Those who have heard me speak on this topic may recall the example I frequently use to illustrate this difference, contrasting a cheaper, ‘designed for the non-expert’ inspection regime with the legacy engineering-led approach.
A common method for the collection and presentation of inspection results is the traffic light approach, identifying results as satisfactory or unsatisfactory. The tools used in inspections are sometimes designed specifically for this approach, illuminating a coloured light rather than recording detailed data.
This can result in data such as that presented in the chart below:
I would expect that anyone presented with this information would infer that the installation was fine until 2024, at which point it failed. There were no signs that anything was going wrong, and there would have been no need to change the maintenance approach, prepare for any repair action, or take pre-emptive measures against failure. Had the O&M contractor asked in 2021 or 2022 for a substantial investment to replace a component, or to take the installation offline and lose income while inspections were undertaken, in my experience the owner would likely have declined. Cases such as these often arrive on my desk described as “sudden and unexpected failures”, often leading to long periods of business interruption for the owner (and their insurers) as spares are ordered and investigations take place.
Contrast this with the actual values recorded by the measurement equipment behind these traffic light reports, presented in this second chart:
With this data, an engineer would be much more justified proposing actions in 2021 or 2022. The sudden and unexpected failure of equipment in 2024 now appears predictable and can be prepared for, either by intervention to slow the progression of whatever is causing the clear trend in the data, or by having plans and spares ready to minimise the impact of the failure and restore full operation in a much shorter timeframe.
Summary
There will always be a trade-off between gold-standard O&M, with comprehensive and expensive inspections and analysis by highly trained engineering staff, and the legitimate desire to not overspend on assets of lesser value. Running every small solar farm or three-turbine wind farm as if it were a nuclear power station is not a desirable (or feasible) solution.
However, my experience of investigations suggests that at the moment the trade-off is being made on the basis of sub-optimal set of data and assuming unrecognised risks. Closing this gap and making sure that the implications of decisions are better understood will bring value to all parties.
About the Author
Ben Lister is a member of the Institute of Engineering and Technology and, prior to joining Hawkins in 2019, spent 10 years working in the power generation, transmission and distribution sectors in both the UK and Europe, specialising in the design and analysis of electrical network equipment such as switchgear and transformers. More recently, he has investigated failures of electrical equipment in industrial and commercial applications ranging from large power stations to factory plant rooms, and has spoken at several conferences and industry meetings on the topic of common failures in renewable energy installations.
