EMT and RMS Modeling of Thyristor Rectifiers for Stability Analysis of Converter-Based Systems
A novel state-space model captures PLL dynamics and commutation for hydrogen electrolysis and HVDC systems.
A team of researchers has published a significant paper on arXiv titled "EMT and RMS Modeling of Thyristor Rectifiers for Stability Analysis of Converter-Based Systems." The work, led by Ognjen Stanojev with co-authors Pol Jane Soneira, Gösta Stomberg, and Mario Schweizer, tackles a critical challenge in power systems engineering: accurately modeling the complex, nonlinear dynamics of thyristor rectifiers. These components are cost-effective workhorses for high-power applications like hydrogen electrolysis and High-Voltage Direct Current (HVDC) transmission, but their line-commutated operation has made small-signal analysis difficult.
The paper's core contribution is a novel nonlinear state-space Electromagnetic Transient (EMT) model formulated in the dq domain. This model is specifically designed to be linearized for small-signal stability studies, a crucial requirement for modern grid planning. It uniquely captures dynamic phenomena often glossed over, including the precise impact of the Phase-Locked Loop (PLL), the commutation angle, and switching delays. By deriving the model in polar coordinates, the researchers offer new insights into how these factors influence overall system behavior.
The proposed models were rigorously verified against a detailed switching simulation and then applied to a practical stability analysis. The team used a modified version of the standard IEEE 39-bus test system, incorporating thyristor rectifier-interfaced hydrogen electrolyzers alongside traditional synchronous generators and advanced grid-forming converters. This testbed represents a realistic future grid scenario, demonstrating the model's direct applicability for engineers designing stable, renewable-heavy power networks that depend on these key power electronic interfaces.
- Proposes a novel nonlinear state-space EMT model for thyristor rectifiers that can be linearized for small-signal analysis.
- Accurately captures PLL dynamics, commutation process, and switching delays—critical details often missed in conventional models.
- Demonstrates practical utility by performing stability analysis on a modified IEEE 39-bus system with hydrogen electrolyzers and grid-forming converters.
Why It Matters
Provides essential modeling tools for ensuring the stability of future power grids reliant on green hydrogen production and HVDC transmission.