The Energy Trilemma: dimensions of energy security - Grid Reliability & Resilience
Previously, I introduced the topic of the World Energy Trilemma as we pave the path forward in ensuring our energy systems are secure, equitable, and sustainable. To the forefront of how to do so comes the first of the three dimensions—energy security with the help of reliability and resilience of electric grid infrastructure.
Grid reliability and resilience are not only critical from a regulatory perspective, but they’re also the most important aspects of every utility. Simply put, does the light come on when you need it?
Reliability can be described as the ability of a power system to deliver electricity in the quantity and with the quality demanded by users. It’s generally measured by interruption indices that assess the magnitude and/or duration of disruptive events. Believe it or not, these disruptive events occur more regularly than you might expect. As a result, systems need to withstand system shocks and should be designed to bounce back as quickly as possible with as minimal disruption as possible, and that when resilience term is applied. Traditional threats to reliability include the loss of generation, loss of transmission, or loss of consumer demand.
Though similar in pronunciation, and linked in significance, reliability and resilience are not one and the same. Resilience, by definition, is the ability to recover. Both critical measures, reliability can be viewed as the fundamental goal of a power grid, with resilience being a necessary component of reliability. Typical threats to resilience can include downed power line(s) as a result of extreme weather, or equipment failure due to age. With the increasing integration of renewable energy resources, overall system inertia is decreasing across wider regions. To maintain grid reliability and resilience, Wide Area Protection, Automation, and Control (WAPAC) systems are being installed and utilized to protect the integrity of the grid.
What are WAPAC systems?
As power grids become more complex and societal demands for environmental protection and sustainable development are increasing, WAPAC applications have become imperative to better operate the grid, prevent blackout events, and ensure energy security. Also known as System Integrity Protection Schemes (SIPS), special protection schemes (SPS), and Remedial Action Schemes (RAS), WAPAC systems, at their most basic, consist of wide-area monitoring systems, communications networks, and advanced data analytics. These systems “collect” critical data such as fault locations and event reports which in turn provide better situational awareness and improved visibility into power systems overall.
WAPAC can be implemented among substations (distributed) or between substations and control center (centralized). Relays at substations either monitor or mitigate relays. Monitoring relays report loading of critical lines to the central controllers every few seconds. They also report trips of these lines—normally due to relay action—within milliseconds so that the controller can implement a strategy to mitigate the resulting overload on the remaining lines and preserve system stability. Mitigating relays at substations or generating locations receive control commands from the central controllers to shed load or generation.
Overall system inertia is decreasing, which will reduce the system control reaction time. There will be need for middle-layer automation and control between the centralized control center layer and substation protection layer to take control across the regional level. This middle layer can be achieved using WAPAC systems which may use peer-to-peer R-GOOSE or client/server PMU/PDC architectures. WAPAC can also be customized to solve the targeted regional grid issues within the given performance constraint using R-GOOSE and/or PMUs over secured communication network.
Power on
Ultimately, an energy system needs to react promptly to any changes to the supply-demand equilibrium and have expeditious bounce-back capabilities. In the developed world, we’ve all become accustomed to the luxury of uninterrupted and reliable power. The grid is the lifeblood of almost any activity—from manufacturing, to transport, to charging your phone. Power on. Understanding this first dimension of the World Energy Trilemmais just part of the equation. Stay tuned for my next blog where I’ll dive into the other two dimensions and examine the role of energy equity and sustainability.
Read more in my recently published article in PACWorld Magazine, “Enhanced Grid Reliability & Resilience using Wide-Area PAC (WAPAC) case studies”