Ensuring grid stability is becoming increasingly challenging as power grids evolve and dynamic stability assessment studies grow more complex. Traditionally, fast-running phasor-domain analyses were sufficient for reliability. However, the faster control dynamics of inverter-based resources now necessitate the integration of slower-running but higher-fidelity electromagnetic transient (EMT) simulations.
Over the past six months, I've had the privilege of leading encoord’s Research and Development efforts alongside Dr. Wallace Kenyon, focusing on developing a groundbreaking commercial hybrid phasor/EMT dynamic stability assessment tool that offers the best of both worlds! This project is supported by the National Science Foundation’s Small Business Innovation Research (NSF SBIR) program.
Embracing Market Insights
Market research is the cornerstone of any successful commercialization endeavor. For me, it meant stepping away from the day-to-day complexities of differential algebraic equations to engage directly with 40 power system researchers, consultants, and planners. Their insights into today's and tomorrow's dynamic stability assessment were immensely helpful in developing our project.
Understanding Dynamic Stability Assessment
For those new to dynamic stability assessment software simulations, here's some context:
Power grids face challenges across various timescales. Planners must address seasonal stressors such as storage deficits and stability stressors such as subsecond fluctuations in power supply and demand.
For decades, the smallest timescale of general stability interest was milliseconds because most energy was generated by spinning masses (e.g., turbines). Phasor-domain simulation was developed to simplify dynamic energy equations by creating constants to represent processes that occurred on sub-millisecond scales. The result was equations that balanced quick solvability with capturing the most important phenomena for stability planners.
Modern energy resources, such as solar panels, often use much faster digital controllers to ensure stable operation. These controllers make decisions on the microsecond timescale. While phasor-domain simulation isn’t necessarily incorrect for modern grids with faster-controlled devices, it can often give a false perception of stability because it simplifies fast dynamic processes. This is where EMT simulation comes in. Unlike phasor-domain simulation, EMT makes far fewer simplifications and captures some processes not represented in phasor-domain. However, this increased accuracy comes at a cost – EMT simulations often take much longer to run.
Balancing model fidelity and solve time is a frequent consideration for me at encoord, so it was invaluable to discuss these challenges with industry experts!
Shared Viewpoints
We found some insightful trends in how the industry was navigating complex dynamic simulation assessments:
What stands out to me from these findings about these findings is they aren’t really tied to dynamics – similar challenges plague almost every domain of energy planning!
Select Viewpoints
From these 40 conversations, there were a few perspectives that I found particularly engaging:
Contemporary Approaches with Existing Software Will Not Work: Today’s solutions to speedup EMT simulation tools, or create hybrid phasor/EMT models with existing software, are not sustainable.
Grid-Forming Inverters May Absolve Need for EMT Detail: Emerging research suggests that EMT detail may not be required for systems with grid-forming inverter-based resources. However, this assumption may not be valid for all system stressors (e.g., faults).
Numerical Noise Vs. Results: Numerical noise from solvers can be indistinguishable from meaningful simulation results. This can be a major source of cognitive burden.
Separation of Domains from Tools: If all you have is a hammer, everything looks like a nail... Our industry may need to think about new applications of modeling domains to answer tomorrow’s questions.
Model Precision: System-wide EMT simulations will not be useful if individual device models do not precisely reproduce real device behavior.
Model Standardization: There may be room for test-driven standard models that would alleviate existing data needs. Standardization could be incentivized with shorter interconnection approval processes.
Our Solution
What I love about being at encoord is that I get to both talk with planners experiencing issues and then use those insights to create novel solutions! Based on the challenges highlighted through our market research, we believe that a hybrid phasor-EMT tool, built on a single software platform, will be a key component for meeting the ever-evolving needs of our industry.
We have adapted our implementation based on these conversations:
What’s valuable about our hybrid approach is that the insights from our tool can be seamlessly integrated into existing dynamic stability assessment software!
Looking Ahead
Currently in Phase I of our NSF SBIR project, we're excited about the potential of our proof-of-concept hybrid tool. With promising early results, we anticipate a commercial launch by 2025.
Follow us on LinkedIn for updates as we continue to innovate and shape the future of energy grid stability assessment.