In a significant advancement for the offshore wind power sector, researchers have identified a critical resonance phenomenon that can occur during the no-load closing of high-voltage AC submarine cables. This issue, highlighted in a recent study by Liu Shidan from the Guangdong Power Grid Co., Ltd. Power Dispatch Control Center, poses a risk to the reliability and efficiency of renewable energy systems, potentially impacting the commercial viability of offshore wind projects.
The study, published in ‘Zhejiang dianli’ (translated as ‘Zhejiang Electric Power’), reveals that the ground capacitance of submarine cables is over 20 times greater than that of traditional overhead lines. This disparity increases the likelihood of resonance events, particularly during the no-load closing process—a phase where the cable is connected to the grid without any load. “Our findings indicate that the integration of long-distance high-voltage AC cables into a weak system can lead to resonance overcurrents,” Liu explained. These overcurrents, while below 1.5 times the power frequency, can still reach high magnitudes, leading to malfunctioning of line differential protection systems.
The implications of this research are profound. As offshore wind farms continue to expand, understanding and mitigating resonance risks will be crucial for ensuring operational reliability. Liu noted, “The existing protection devices, despite their current compensation capabilities, struggled to manage significant capacitive resonant differential currents, which ultimately led to the protection system’s failure.” This highlights the urgent need for improved engineering solutions to safeguard these critical infrastructures.
To address these challenges, the study proposes a comprehensive response strategy that includes optimizing the wiring of secondary circuits in protection devices and dynamically adjusting the threshold for differential current actions based on real-time system conditions. These measures aim to enhance the resilience of offshore wind farms against resonance-related failures, which could help prevent costly outages and maintenance issues.
The research not only sheds light on a previously underexplored aspect of offshore wind farm operations but also suggests practical engineering solutions that could shape future developments in energy transmission and protection systems. As the world pivots towards renewable energy sources, ensuring the reliability of offshore wind farms will be essential for meeting energy demands and achieving sustainability goals.
For more information about Liu Shidan’s work, you can visit the Guangdong Power Grid Co., Ltd. Power Dispatch Control Center’s website at lead_author_affiliation.
