All around the world, grid operators are being confronted with the same challenge: the fact that their equipment is reaching old age. It is no longer uncommon to see power transformers with a service life of 50 years or more. Therefore, there are questions that every grid operator is faced with: What condition is my fleet in? How long will our transformers last, and when will we have to invest in new ones? This situation is aggravated by fluctuating, higher loads resulting from renewable energy sources that increasingly push crucial transformers that are needed to ensure a stable power supply to their limits.
Clever fleet management for transformers
Using the TESSA® FLEETSCAN 2D analysis system, asset and service managers always have an overview of the condition of their transformers, making it easier to plan maintenance, updates and investments.
Clever fleet management for transformers
Using the TESSA® FLEETSCAN 2D analysis system, asset and service managers always have an overview of the condition of their transformers, making it easier to plan maintenance, updates and investments.
That is why Reinhausen developed a condition-based method to identify transformers in critical condition at an early stage: TESSA® FLEETSCAN 2D. The system is based on a two-dimensional assessment matrix. First, the likelihood of functions failing is calculated in order to model the reliability of the fleet. The second dimension then considers the loss-of-life and is important for making long-term investment decisions.
Reinhausen designed TESSA® FLEETSCAN 2D as a manufacturer-independent assessment tool. This means it can offer all transformer fleet operators a lean solution for keeping their fleet up and running. This is how it works:
1. Collecting condition data at the transformer
1. Collecting condition data at the transformer
A sufficient database is essential to carry out the condition assessment. To keep failure times and assessment work to a minimum, TESSA® FLEETSCAN 2D includes three test stages. Depending on how detailed the assessment needs to be, not all three stages have to be carried out. Transformer data is already available in many cases, so the work involved in recording the data is minimal.
In the first stage, the operator provides the data which is already available. Examples include the master data of the transformers, measurements that have already been carried out and maintenance history information. The next stage involves an on-site appraisal which is carried out during operation. In the visual inspection, an MR expert uses a checklist to examine the transformer for signs of corrosion, leaks and visible damage to the bushings and fans. They also carry out infrared thermography and a complete oil analysis. If, after the first two stages, there are any indications of more significant damage, MR performs targeted testing while taking extensive measurements in the third stage. These include dynamic resistance and partial discharge measurements and require the transformer to be taken off the grid.
2. Managing and accessing transformer data online
2. Managing and accessing transformer data online
TESSA® FLEETSCAN 2D provides the option to save all collected data in a clear overview using browser-based software. This allows grid operators to retrieve all collected information and assessments of all equipment for any transformer in the fleet at any time.
3. Condition analysis of the transformers
3. Condition analysis of the transformers
After the data has been recorded, it is time to move on to the core element of TESSA® FLEETSCAN 2D: the evaluation. Using an algorithm developed by MR and the University of Wuppertal, the condition analysis is carried out in two indexes: the failure risk index and the loss-of-life index. The failure risk index measures the likelihood of functions failing. These values provide important reference points for the maintenance strategy, which is crucial for the OpEx budget. The loss-of-life index is a key variable when making long-term investment decisions, and is therefore relevant for the CapEx budget.
The results of the two indexes are transferred into an x/y diagram for the assessment. The condition of the fleet can thus be visualized simply: The more transformers located in the quadrants near the origin, the better the condition of the fleet, and vice versa.
4. Recommendations for the transformer fleet
Once the assessment is complete, an MR expert checks the results and the plausibility of the data and offers recommendations. The grid operator will then receive a comprehensive report which they can use to derive the measures, maintenance tasks and investment decisions that need to be taken. The service life of the fleet can be increased by implementing targeted measures, without having to make a huge investment. Depending on the condition of the fleet, MR recommends that the TESSA® FLEETSCAN 2D assessment be repeated every three to five years.
„The TESSA® FLEETSCAN 2D method supports us in making operational and strategic decisions in Asset Management.“
