American Electric Power
Historically, utilities have used inspections and time-based maintenance to drive decisions on safety and failure prevention. The inspections and time-based maintenance still hold value, but AEP Transmission is also implementing real-time asset monitoring to provide more current and additional data points for failure decisions. AEP Transmission is using transformer monitoring to provide operational alarms that are used in real-time to reduce risk of failure. The combination of off-line data, on-line data, data analytics, and data trends to make decisions on failure prevention and asset safety is a powerful combination.
In the past, our internal teams have used alarms, inspections, and time-based maintenance to drive decisions on failure prevention and safety. Using traditional data such as inspections and time-based maintenance information in conjunction with real-time monitoring data that is brought into one system of alarms and emails creates a data-driven process for making the best decisions on failure prevention and asset safety.
Transformer Asset Monitoring
In AEP Transmission, the Station Equipment Standards group is responsible for the standards and ordering of substation equipment. They work with Transmission Technical Field Services (TFS), the Transmission System and Asset Monitoring team, and other Engineering Standards teams to create a standard transformer monitoring package for EHV transformers.
For a 765-kV single-phase transformer, the standard monitoring package consists of: bushing health, partial discharge, temperatures, fans, pumps, legacy alarming, eight gas monitor, and a composite gas monitor.
The standard monitoring package data is collected at a data concentrator on the transformer and sent across the non-critical LAN to a C30 relay in the control house. The traditional legacy data is sent via a critical LAN through the RTU to SCADA, and then is connected via a PI to PI connection to the Station PI data repository. The Station PI allows multiple departments to utilize the data for various analyses. 
The detailed transformer communication path that was chosen by AEP Transmission takes data from the transformer all the way through the network to the Station PI database. The communication path process and infrastructure chosen allows AEP Transmission to meet security requirements and user requirements. The communication path was a process created with security, engineering standards, and the TSAM teams. 
Bringing It All Together
Several steps were needed to bring this project into a functional process that created value for AEP Transmission. The first step involved the creation of the data, communications, and security infrastructure. This data was brought into, and used by, the system with asset-specific alarms and emails that alert the TSAM team to asset health issues and impending failure events. These tools and infrastructure were used to help achieve two main goals: 1) safety and 2) failure prevention.
Different processes, policies, and procedures were needed to solve each of these problems. For safety and failure prevention, operational alarms and alerts are crucial to reacting appropriately and in a timely manner to quick-acting failures. Condition-based monitoring and real-time awareness are key to maintaining safety and preventing asset destruction. Using our current process, the AEP Transmission System and Asset Monitoring (TSAM) team has prevented the failure of eight transformers (saving tens of millions of dollars) and created several monitoring-related safety practices.
For example, TSAM prevented the first catastrophic failure in June 2014 of an asset using online partial discharge information and online dissolved gas data. This new data provided us information to take this unit out of service. Loose leads were found in this particular item and repaired.
This is a big process change at AEP Transmission. Over time, AEP Transmission will continue to use real-time data to anticipate failures and for asset safety on the right assets at the right time — with significant cost savings anticipated.
The asset health project has met its objectives in the two main business cases for asset safety and failure prevention.
Heading Into the Future
There are several next steps in the AEP Transmission journey. The first is taking this process to more of our assets. TSAM continues to review other assets for monitoring. TSAM has created a standard for circuit breaker monitoring. Pilots are being completed for the monitoring of 138-kV transformers, underground cables, lines, capacitor banks, and CCVT.
As more data is available, all assets will need improved data analytics and algorithms so that we can find trends for failure prevention and asset safety in an automated fashion. These steps will allow all of these assets to receive the benefits of asset safety and failure prevention.
In conclusion, to drive the best failure prevention and asset safety, you need to make use of real-time data, offline data, and nameplate data in combination to make the right decision at the right time.
- Schneider, C; Phillips, K.; Spurlock, P., “Lessons Learned from Failed Assets at EHV,” COMET conference, October 2014.
- Phillips, K.; Schneider, C; Cambraia, P; Munson, M, “Automated Aggregation of Data for Asset Health Analysis,” CIGRE Grid of the Future Symposium, October 20, 2013.