Transformer health and risk indexing, including data quality management

Managing transformers is a challenging responsibility for grid operators. A decision support
dashboard presenting the actual transformer health and condition can support asset managers in
making the right decisions to maintain or improve the reliability and safety of the grid. This paper
describes an approach to transformer health indexing and decision support modelling which is
consistent with the asset management approach in for example the Publicly Available Specification
PAS 55 and the new standard ISO 55000.
The health index model discussed in this paper, being the heart of the decision support tool, is
developed with dedicated transformer condition assessment functions in combination with usage based
estimations and a statistical approach using Monte Carlo simulations. This results in a colour coding
health index with two dimensions. The colour itself gives an indication of expected remaining life or
additional maintenance requirements and the colour intensity gives an indication of the assessment
reliability, thus providing a clear and easily readable dashboard for the asset manager.
The health index is part of a risk based approach for further decision support. Next to the transformer
health, this approach involves impact categorization, presentation and prioritization, and supports
selecting optimum sets of mitigation actions to manage the risks associated with the transformer
health