In the vast expanse of China’s offshore wind farms, a new strategy is emerging to stabilize the grid, integrating wind power, energy storage, and high-voltage direct current (HVDC) transmission systems. This innovative approach, developed by Yangqing Dan at the Center of Power Grid Planning, Economic Research Institute of State Grid Zhejiang Electric Power Co., Ltd., aims to bolster the frequency stability of onshore power grids, a critical challenge as renewable energy sources proliferate. The strategy, published in Energies, holds significant promise for the energy sector, particularly as China accelerates its offshore wind power development, aiming to reach 90 GW by 2030.
The core of the problem lies in the increasing share of non-synchronous generators like wind turbines and energy storage systems, which, while clean and abundant, reduce grid inertia and frequency regulation capabilities. “With the continued deployment of renewable energy, the share of non-synchronous generators has increased, leading to a decline in grid inertia and frequency regulation capabilities,” explains Dan. This poses serious threats to system frequency stability, making innovative solutions imperative.
Dan’s strategy involves a coordinated frequency regulation approach that integrates power generation, energy storage, and DC transmission. The method employs DC voltage as a transmission signal to coordinate the responses of wind turbines and energy storage systems, enhancing the grid’s frequency stability. This is particularly crucial for offshore wind farms connected via MMC-HVDC transmission, where wind turbines are decoupled from onshore grids. “Offshore wind power can only indirectly participate in onshore grid frequency regulation through the MMC-HVDC system,” Dan notes, highlighting the complexity of the challenge.
The strategy comprises two main components: a primary frequency regulation method based on constant DC voltage control and a secondary frequency regulation strategy that balances AC frequency regulation and the recovery of the state of charge (SOC) of the energy storage system. The results, tested on a modified IEEE 39-bus system, are promising. The minimum frequency value can be increased by 37.5%, and the system frequency can be restored to its initial state after secondary frequency modulation.
The implications for the energy sector are profound. As the world transitions to cleaner energy sources, maintaining grid stability becomes increasingly complex. This research offers a roadmap for integrating diverse energy sources and storage systems to enhance grid stability. For energy companies, this means new opportunities for innovation and collaboration in developing more resilient and efficient power systems. The strategy also underscores the importance of coordinated control methods, which could lead to more sophisticated and adaptive grid management systems.
As China and other countries ramp up their renewable energy investments, Dan’s work provides a crucial framework for ensuring that these new power sources contribute to a stable and reliable grid. The strategy’s success in simulation tests paves the way for real-world applications, potentially reshaping how offshore wind power and energy storage systems are integrated into the grid. The findings, published in the journal Energies, offer a glimpse into the future of energy management, where coordination and adaptability will be key to maintaining stability in an increasingly complex energy landscape.
