P37.105: Balance of Substations: Batteries, Arresters and Ratings
Objective
The project objective is to determine how to optimize the maintenance of various substation assets and maximize their service lives. Equipment under test varies by project year. Research focuses on equipment that is not typically designated as a major asset but still affects the reliability, safety, and longevity of substations. Examples of such assets include battery banks, disconnect switches, instrument transformers, and surge arresters.
Research Value
This research can provide the following value:
- Provide guidance regarding asset life cycles, including specific assets such as monitoring of surge arresters and battery systems
- De-risk novel technologies associated with asset inspection, monitoring, and assessment via robotics
- Support utilities in making informed decisions about substation ratings, including improved thermal models to optimize power output and guidance for applying this information in overall transmission system ratings
Planned 2025 Research
Continue development of surge arrester sensor to monitor pending arrester failure: This multi-year task evaluates the long-term durability of EPRI’s surge arrester failure sensor. The approach involves the monitoring of new, aged, and failing arresters in the controlled, 138-kV research substation environment to increase the sensor’s data set for future analysis. This allows for examination of the impacts of a substation environment on sensor performance while enabling easy access to the sensors if problems occur.
Assess performance of battery monitoring systems: Assess battery monitoring systems from several manufacturers. Use bench testing and battery emulators to create repeatable test plans that allow for comparison between systems that may otherwise require different battery chemistries or configurations.
Evaluate robot chassis for applicability to substation inspection: This research explores the feasibility of autonomous mobile robots for substation inspections, investigating their potential to complement human inspectors, be shared across substations, operate with minimal supervision, be portable, and ultimately determine if they currently complement or supplement human inspectors for improved efficiency, safety, and reliability in substation inspections. This task expands on work from 2024 by evaluating additional technologies.
Issue updates to EPRI’s Increased Power Flow Guidebook for 2025: This effort advises utilities on how to calculate and apply ampacity ratings to substation equipment, pursuant to NERC requirements and FERC Order 881, which shifts the industry from ambient adjusted ratings that vary with air temperature to dynamic line ratings (DLRs) that vary with wind speed. In addition to applying DLRs to bus ratings, the new designations may result in the most limiting series element designation applying to station equipment, instead of the transmission line, for many circuits in 2025.
Anticipated Deliverables
| Deliverable | Date |
|---|---|
| Robotics Assisting Electrical Substation Inspectors (Technical Update) | December 31, 2025 |
| Insights and Considerations from Substation Battery Monitoring System Evaluation and Testing (Technical Update) | December 31, 2025 |
| EPRI Increased Power Flow Guidebook—2025: Increasing Power Flow in Lines, Cables, and Substations (Technical Update) | December 31, 2025 |
| Transmission Ratings Workstation: 2025 (Software) | December 31, 2025 |
| Arrester Condition and Failure Monitoring | December 31, 2025 |
Past EPRI Research on Topic
| Product ID | Title | Description | Published Date |
|---|---|---|---|
| 3002027110 | Insights and Considerations from Substation Battery Monitoring System Evaluation and Testing | Report describing work performed by EPRI to evaluate various battery monitoring systems through 2023 | December 2023 |
| 3002027105 | Transmission Rating Workstation (TRW) STLoad 2023 | 2023 software release of Transmission Ratings Workstation for performing rating studies and evaluating and optimizing static ratings, real-time ratings, and forecasted ratings for transmission equipment and entire circuits | December 2023 |
| 3002027331 | Increased Power Flow Guidebook (The Platinum Book) | Technical reference book that accompanies the Transmission Rating Workstation STLoad software | December 2023 |
| 3002027114 | Arrester Condition and Failure Monitoring | Description of the development of the arrester monitor, laboratory test results, and results from two field demonstrations through 2023 | December 2023 |