Cost benefit analysis: The financial advantages of online transformer monitoring

When implementing a transformer monitoring solution, it is important to consider the economic implications of adopting this technology. Online transformer monitoring, with its diverse configurations, emerges as a cost-effective remedy, particularly when confronting the spectre of high-value transformer asset failures. The capacity to remotely oversee transformer assets and respond promptly to precise data not only enhances operational efficiency but also yields significant financial advantages.

How to determine the ROI?

A ‘return on investment’ can be evaluated by examining published literature on the rate of transformer failure, applying this to a lifetime average installation of a power transformer and then calculating the impact of downtime over the lifetime of a wind farm. The load duration curve for maximum and minimum export potential can be considered along with an average market value for the associated energy price within a given market. This gives you two outputs which can be considered together to make an investment decision for remote online monitoring. What is the probability of failure and associated costs involved with choosing whether or not to invest in online monitoring?

The business case

In this case we have used publicly available information for an offshore wind installation to formulate a high-level business case for remote online transformer monitoring. The following inputs have been considered:

• Balance of plant

• Commercial market price

• Annual risk of transformer failure

• Repair & replacement time

We also considered some typical load duration curves for offshore wind farms from publicly available data.

Assumptions for the business case

We have used a representative 500 MW wind farm project, with a 5 MW individual turbine size with 2 onshore substations each with a redundant transformer and an offshore substation with a redundant transformer. Transformers, if they experience a catastrophic failure can take 6 months to replace, in many cases longer.

The numbers

With all these parameters considered a wind farm could be exposed to a conservative estimate of £4 million in lost revenue due to a reduction in export.

Payback period

The average cost of a solution in the market, is less than a week of downtime over the wind farm lifetime of 25 years for a project owner, and less than a day for an OFTO. This does not take into account operational savings made from moving to a condition-based maintenance strategy, or the potential positive impact on insurance premiums.