How many grid-forming converters does the “new-type power system” need?

Transition to Grid-Forming Converters

“The rapid expansion of renewable energy sources such as wind and solar has pushed power systems into a new ground, known as ‘new-type power systems’, which rely heavily on inverter-based resources,” explains Mr. Guoxuan Cui, the lead author from Imperial College London. “GFMs are crucial as they actively stabilize the grid by independently forming voltage and frequency, unlike traditional GFLs which depend on a stable grid.”

They published their study on June 19, 2025, in iEnergy.

Techno-Economic Analysis of GFM Deployment

The research systematically analyses the factors that affect the optimal penetration of GFMs in power systems from a techno-economic perspective. By integrating long-term planning, short-term operational strategies, and dynamic stability requirements, the study uncovers critical trade-offs between grid reliability and cost efficiency.

“Our study reveals that the optimal penetration of GFMs depends on a delicate balance between stability requirements and economic considerations across both planning and operational timescales,” says Mr. Cui.

From a system planning perspective, the analysis accounts for both hardware and software requirements. GFMs require robust components—such as enhanced DC-link capacitors and high-performance power semiconductors—as well as advanced control algorithms, which collectively contribute to higher upfront investment costs. “However, these investments may be justified by reducing the reliance on conventional grid-support equipment like synchronous condensers,” Mr. Cui adds.

Hybrid GFM/GFL Approach for Enhanced Flexibility

A notable contribution of this study is the introduction of a hybrid control approach during power system operation stage, where converters dynamically switch between grid-forming and grid-following roles depending on real-time grid conditions. This strategy offers significant operational cost reductions compared to conventional fixed-mode systems. “Dynamic allocation of converter modes allows for better management of renewable energy variability and ensures grid stability in a cost-effective manner,” emphasizes Dr. Fei Teng, senior author and associate professor at Imperial College London.

Advanced Optimization and Scenario Analysis

To assess how GFM penetration and allocation decisions respond to diverse system conditions, the researchers implemented advanced optimization techniques alongside scenario-based simulations. These tools allowed them to evaluate how varying levels of renewable energy and grid strength affect the ideal control mode configuration. Their results demonstrate that dynamically adjusting the share of GFMs not only strengthens system security—including frequency, voltage, and small-signal stability—but also reduces total system costs by optimizing both capital (CapEx) and operational expenditures (OpEx).

Policy and Industry Implications

“This research supports a crucial transition for power systems worldwide,” concludes Mr. Cui. “As power grids become increasingly renewable energy-dominated, identifying the optimal number of GFMs is key to achieving secure, economically viable, and sustainable energy systems.” Dr. Teng adds, “The findings offer valuable insights for policymakers, grid operators, and renewable energy technology developers, aiding better decision-making and facilitating efficient GFM deployment in future power systems.”