Snohomish County

Arlington Microgrid Solar Smoothing Pilot Project Analysis

The variability of photovoltaic (PV) generation from medium to large PV plants is a challenge for the balancing authorities like the Bonneville Power Administration (BPA) that are responsible for maintaining the balance between load and generation within their territory. Snohomish County PUD is currently conducting a pilot project with BPA to better understand how battery energy storage systems can be used to smooth the variations in solar output caused by changes in cloud cover. There are a number of different algorithms used and studies conducted to determine the quality/ success of the smoothing as well as the associated battery degradation. It would be beneficial to review the different methods and papers, talk to industry experts and create a computer model to help the utility industry better understand which methodology to use with the best compromise of grid benefits versus battery degradation. This project will use analysis and data from an actual project—a 500 kWac solar array paired with a 1MW/1MWh lithium-ion battery energy storage system at the Arlington Microgrid site in Arlington, WA. This project may involve the following: 1. Review existing methods, studies, and data. 2. Interview engineers from SnoPUD, BPA, Hitachi, etc. 3. Create a computer model to simulate the different solar smoothing and capacity firming methods. 4. Review actual data and compare to model. 5. Write a paper regarding the analysis, method comparison, and recommendations. The outcomes this student team will work to achieve are: -Create a computer model to simulate the various methods of solar smoothing, capacity firming, etc. -Write a paper regarding the analysis, method comparison and recommendations.