Feb 09 2025 41 mins 9
Power grids operate like an intricate ballet of energy generation and consumption that must remain perfectly balanced at all times. The grid maintains a steady frequency (60 Hz in North America and 50 Hz in many other regions) by matching power generation to demand in real-time. Traditional power plants with large rotating turbines and generators play a crucial role in this balance through their mechanical inertia—the natural tendency of these massive spinning machines to resist changes in their rotational speed.
This inertia acts as a natural stabilizer for the grid. When there’s a sudden change in power demand or generation, such as a large factory turning on or a generator failing, the rotational energy stored in these spinning masses automatically helps cushion the impact. The machines momentarily speed up or slow down slightly, giving grid operators precious seconds to respond and adjust other power sources.
However, as we transition to renewable energy sources like solar and wind that don’t have this natural mechanical inertia, maintaining grid stability becomes more challenging. This is why grid operators are increasingly focusing on technologies like synthetic inertia from wind turbines, battery storage systems, and advanced control systems to replicate the stabilizing effects traditionally provided by conventional power plants.
Alex Boyd, CEO of PSC, a global specialist consulting firm working in the areas of power systems and control systems engineering, believes the importance of inertia will lessen, and probably sooner than most people think. In fact, he suggested stability based on physical inertia will soon be the least-preferred approach. Boyd recognizes that his view, which was expressed while he was a guest on The POWER Podcast, is potentially controversial, but there is a sound basis behind his prediction.
Power electronics-based systems utilize inverter-based resources, such as wind, solar, and batteries. These systems can detect and respond to frequency deviations almost instantaneously using fast frequency response mechanisms. This actually allows for much faster stabilization compared to mechanical inertia.
Power electronics reduce the need for traditional inertia by enabling precise control of grid parameters like frequency and voltage. While they decrease the available physical inertia, they also decrease the amount of inertia required for stability through advanced control strategies. Virtual synchronous generators and advanced inverters can emulate inertia dynamically, offering tunable responses that adapt to grid conditions. For example, adaptive inertia schemes provide high initial inertia to absorb faults but reduce it over time to prevent oscillations.
Power electronic systems address stability issues across a wide range of frequencies and timescales, including harmonic stability and voltage regulation. This is achieved through multi-timescale modeling and control techniques that are not possible with purely mechanical systems.
Inverter-based resources allow for distributed coordination of grid services, such as frequency regulation and voltage support, enabling more decentralized grid operation compared to centralized inertia-centric systems. Power electronic systems are essential for grids with a high penetration of renewable energy sources, which lack inherent mechanical inertia. These systems ensure stability while facilitating the transition to low-carbon energy by emulating or replacing traditional generator functions.
“I do foresee a time in the not-too-distant future where we’ll be thinking about how do we actually design a system so that we don’t need to be impacted so much by the physical inertia, because it’s preventing us from doing what we want to do,” said Boyd. “I think that time is coming. There will be a lot of challenges to overcome, and there’ll be a lot of learning that needs to be done, but I do think the time is coming.”
This inertia acts as a natural stabilizer for the grid. When there’s a sudden change in power demand or generation, such as a large factory turning on or a generator failing, the rotational energy stored in these spinning masses automatically helps cushion the impact. The machines momentarily speed up or slow down slightly, giving grid operators precious seconds to respond and adjust other power sources.
However, as we transition to renewable energy sources like solar and wind that don’t have this natural mechanical inertia, maintaining grid stability becomes more challenging. This is why grid operators are increasingly focusing on technologies like synthetic inertia from wind turbines, battery storage systems, and advanced control systems to replicate the stabilizing effects traditionally provided by conventional power plants.
Alex Boyd, CEO of PSC, a global specialist consulting firm working in the areas of power systems and control systems engineering, believes the importance of inertia will lessen, and probably sooner than most people think. In fact, he suggested stability based on physical inertia will soon be the least-preferred approach. Boyd recognizes that his view, which was expressed while he was a guest on The POWER Podcast, is potentially controversial, but there is a sound basis behind his prediction.
Power electronics-based systems utilize inverter-based resources, such as wind, solar, and batteries. These systems can detect and respond to frequency deviations almost instantaneously using fast frequency response mechanisms. This actually allows for much faster stabilization compared to mechanical inertia.
Power electronics reduce the need for traditional inertia by enabling precise control of grid parameters like frequency and voltage. While they decrease the available physical inertia, they also decrease the amount of inertia required for stability through advanced control strategies. Virtual synchronous generators and advanced inverters can emulate inertia dynamically, offering tunable responses that adapt to grid conditions. For example, adaptive inertia schemes provide high initial inertia to absorb faults but reduce it over time to prevent oscillations.
Power electronic systems address stability issues across a wide range of frequencies and timescales, including harmonic stability and voltage regulation. This is achieved through multi-timescale modeling and control techniques that are not possible with purely mechanical systems.
Inverter-based resources allow for distributed coordination of grid services, such as frequency regulation and voltage support, enabling more decentralized grid operation compared to centralized inertia-centric systems. Power electronic systems are essential for grids with a high penetration of renewable energy sources, which lack inherent mechanical inertia. These systems ensure stability while facilitating the transition to low-carbon energy by emulating or replacing traditional generator functions.
“I do foresee a time in the not-too-distant future where we’ll be thinking about how do we actually design a system so that we don’t need to be impacted so much by the physical inertia, because it’s preventing us from doing what we want to do,” said Boyd. “I think that time is coming. There will be a lot of challenges to overcome, and there’ll be a lot of learning that needs to be done, but I do think the time is coming.”
