Electricity Asset Management Plan 2019-2029
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Vector Limited://
Population and Age The age profile of Vector’s power transformers is given in the graph below.
Figure 4-11 Age profile for power transformers
Condition and Health Our fleet of power transformers consist of 37 different models and types with different makes and models of tap changers but since 2000 we have standardised on a specific range of models that reduces the type and number of spares required. Our transformer fleet is ageing but our active monitoring of the health and condition of these important assets is ensuring that we get the optimum life from this fleet. Strategy Power transformers have very long in-service life expectations and are designed to operate at full continuous rating for approximately 25 years. Continuous use at full rating will result in the insulation life of the paper being exhausted and failure will become imminent. Vector, not unlike most utilities worldwide, plans the network with N-1 contingency in its network and as a result the loading on our power transformers is rarely more than 50% of its nameplate rating for the majority of its operating life. At this level of loading we can expect service lives well in excess of 50 years as shown in the graph above. Through annual oil analysis and insulation testing, the condition of the transformer can be monitored and any developing faults detected so as to ensure continuity of service. Through this process, transformer replacement can be forecast years in advance. However, we are in the process of developing a CBARM model for our power transformer fleet to improve our forward planning of replacement and refurbishment. This model will be completed in FY19. Depending on the condition of a transformer we may also refurbish a transformer if the net present value is more beneficial than the cost of procuring a new transformer. Transformer replacement is not only driven by condition and criticality but also growth. If and when a transformer needs to be replaced with a transformer of greater capacity the existing transformer will be deployed somewhere else in the network if the remaining life of the unit warrants reuse. Our planning for transformer replacement also considers alternative technology options such as a BESS system and/or load control to defer installation of a new transformer and the Symphony load scenario will be considered as part of our evaluation and business case development with regard to if and when a transformer should be replaced. We are also planning to trial dynamic ratings as a method to extend the asset life of some of our older power transformers and the business case and planning for proof of concept are presently being prepared. Real time ratings will be obtained from existing measuring devices and this along with the application software will be interfaced with our DERMS. We are also engaged in an initiative with VIA, a US based artificial intelligence start-up, to establish a secure database for
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