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A New Twist on Old (Time-Tested) Grid Analysis Methods

In shepherding the grid through a massive renewable evolution, grid planners face many challenges. Among those, I’d like to focus on these 3:

  1. Future Uncertainty: There are numerous future scenarios to consider when planning in the 5, 10, and 20 year horizons.

  2. Analysis Burden: Today’s analysis tools and approaches take time and specialized skills, which makes it difficult to assess many scenarios (see point 1)

  3. Evolving Technology: Inverter technology (like the emergence of grid-forming inverters) is evolving quickly. This is good news because of the enhanced performance, but the adoption and impact of the new technology further increases uncertainty in grid planning.

To help address these challenges, we’ve worked closely with the Midcontinent Independent System Operator (MISO) to develop a new analysis to screen for voltage stability risks. Our new method is:

  1. much faster than time-domain approaches to analyzing stability, and

  2. differentiates among resource performance by capturing critical characteristics of emerging technologies like grid-forming inverters (GFM) v. grid-following inverters (GFL), which helps planners understand the potential impact of the new technology.

We accomplish this by combining traditional steady-state analysis approaches for voltage stability (to enable speed) with advanced impedance-based analysis using detailed EMT simulations (to capture critical characteristics of resources).

Our initial results are very encouraging! We’ve benchmarked our new Dynamic Impedance Method against detailed EMT simulations and found strong agreement between the analysis approaches. The details are documented in our paper (available here), which was presented at the 22nd Wind & Solar Integration Workshop and published in the workshop’s proceedings.

WISO23_IET-024 Conference Paper_Richwine_Aug28
Download PDF • 1.03MB

Since then, we’ve tested our new method on a large piece of the central MISO system and have seen very encouraging results, which have been shared in MISO’s Resource Attributes Workshop (see slides 65-74). Stay tuned for a subsequent post with details!

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