In the dynamic world of renewable energy, the integration of offshore wind farms into onshore power grids is a critical endeavor, but it’s not without its challenges. One significant hurdle is the phenomenon of subsynchronous oscillation (SSO), which can threaten the stability of these interconnected systems. A recent study, led by Fusen Xiang from the College of Electrical and Information Engineering at Hunan University in Changsha, China, delves into this issue, offering insights that could reshape the future of hybrid wind farms.
Xiang and his team focused on the integration of offshore wind farms comprising both direct-drive and doubly fed induction generators into onshore grids via voltage source converter-based high-voltage direct current (VSC-HVDC) transmission systems. Their research, published in IEEE Access, reveals that SSO can indeed occur, but the type of wind turbine plays a crucial role in how these oscillations manifest.
“Our findings show that systems containing doubly fed turbines exhibit SSO, whereas systems with only direct-drive turbines experience oscillations in different frequency ranges,” Xiang explains. This discovery is a significant step forward in understanding the behavior of hybrid wind farms, which have received less attention in existing research.
The study developed mathematical models for direct-drive, doubly fed, and hybrid wind farms connected through VSC-HVDC. By employing modal analysis and eigenvalue analysis, the researchers identified various oscillatory modes and pinpointed the doubly fed turbine as the primary contributor to SSO in hybrid systems. This granular understanding could lead to more targeted solutions for mitigating SSO and enhancing the stability of hybrid wind farms.
The research also examined the impact of key parameters, such as the wind turbine’s DC-link capacitance, AC-side reactance, the VSC-HVDC AC-side reactor, and the PI controller settings of the doubly fed turbine’s rotor-side converter, on SSO frequency and damping ratio. These findings provide a roadmap for optimizing these parameters to minimize the risk of SSO, thereby improving the overall reliability and efficiency of hybrid wind farms.
The commercial implications of this research are substantial. As the energy sector continues to shift towards renewable sources, the ability to integrate offshore wind farms efficiently and safely is paramount. By addressing the challenges posed by SSO, this research paves the way for more robust and stable hybrid wind farm designs, which could attract more investment and accelerate the adoption of wind energy.
Xiang’s work underscores the importance of interdisciplinary approaches in tackling complex energy challenges. “Our study highlights the need for a comprehensive understanding of the interactions between different types of wind turbines and the grid,” Xiang notes. “This knowledge is essential for developing effective strategies to ensure the stability and reliability of future wind energy systems.”
As the energy sector continues to evolve, the insights from this research could shape future developments in the field. By providing a deeper understanding of SSO and its mitigation, Xiang’s work could influence the design and operation of hybrid wind farms, ultimately contributing to a more stable and efficient energy grid. The study, published in IEEE Access, serves as a valuable resource for researchers, engineers, and industry professionals seeking to advance the integration of offshore wind energy.
