WIRAB Webinar Series – Grid Reliability and the Changing Resource Mix


The Western Interconnection Regional Advisory Body (WIRAB) hosted a series of five tutorials on how the changing resource mix affects grid reliability. Power system experts Debbie Lew and Nick Miller broke down grid reliability needs into long-term, medium-term, and short-term timeframes to discuss how to consider grid reliability with the changing grid. Although the subject matter is technical, these tutorials are at a level for a non-technical audience such as regulators and policymakers.

Long-Term Reliability – Resource Adequacy

Wednesday, April 15, 2020, at 2:00 PM MT (1 Hr) 

Long-term reliability is ensuring supply/demand balance over a year and years into the future, which is achieved through resource adequacy and capacity planning. Questions to consider for long-term reliability include:

  • How do we define a resource adequate system when we have variable renewable resources?
  • Does resource planning using a fixed planning reserve margin still make sense?
  • How does demand response help?
  • What is the role of batteries?

Slides and the recording are posted HERE.

Medium-Term Reliability – System Balancing

Wednesday, April 22, 2020, at 2:00 PM MT (1 Hr) 

Medium-term reliability is ensuring supply/demand balance over the course of a single day and by having resources available to respond to system contingencies that could occur over the day. Questions to consider for medium-term reliability include:

  • How do we balance a system with variable renewable resources?
  • What do system operators need to do differently?
  • How can renewables be used to help balance the system?
  • What are some best practices of operators around the world?

Slides and the recording are posted HERE.

Short-Term Reliability – System Stability (Two Sessions)

Short-term reliability is ensuring frequency, transient, and small-signal stability. PV, wind, and batteries connect to the grid through an inverter, which responds to grid events differently than conventional generators. This subject matter is the most technical of all the tutorials, but it is still intended for a non-engineering audience.

Introduction and Frequency Response

Wednesday, April 29 at 2:00 PM MT (1 Hr) 

Frequency response refers to the power system’s ability to recover from the loss of generation. Inverter-based resources do not provide inertia that helps the grid recover from these events. How will a low inertia system operate, and how can inverter-based resources help?

Slides and the recording are posted HERE.

Transient and Small Signal Stability

Wednesday, May 6 at 2:00 PM MT (1 Hr) 

Transient stability refers to the grid’s ability to reach a stable condition following a large disturbance in the system. Small signal stability refers to the power system’s ability to reach its stable condition after small disturbances like minor fluctuations in load and generation. How do inverter-based resources lead to weak grids, and what are the implications of weak grid systems? What can we do to mitigate these issues?

Slides and the recording are posted HERE

Current Issues: 100% Clean Energy Policy Targets, Distributed Energy Resources (DERs), and Grid Reliability

Wednesday, May 20 at 2:00 PM MT (1.5 Hrs) 

Many states, cities, utilities, and customers now have 100% clean energy targets, and to achieve these targets, there will likely be an increase in Distributed Energy Resources. Questions to consider in this wrap-up session include:

  • How can they ensure grid reliability on all timescales while meeting these targets?
  • Which problems do we think we can solve and which problems are yet to be solved?
  • As they increase their clean energy portfolios, which issues will they face first?
  • What are the impacts of DER on the reliability of the power grid at the distribution and bulk power system level?
  • What processes can be instituted to mitigate distribution system impacts and guide development to needed locations?
  • How can we reduce DER impacts on reliability?

Slides and the recording are posted HERE.


Debbie Lew

Debbie is an independent consultant. Previously, Debbie worked at GE Energy Consulting and the National Renewable Energy Laboratory on the integration of wind, solar, and distributed energy resources into the power system.

Nick Miller

Nick is also an independent consultant with HickoryLedge LLC and recently retired from GE Energy Consulting after 3/8 century of work on bulk power systems; today, he focuses on wind and solar power integration. Nick will help deliver the short-term system stability and 100% clean energy tutorials along with Debbie.

For more information, please reach out to Eric Baran at ebaran@westernenergyboard.org.