In the vast landscapes where wind turbines dot the horizon, the integration of wind power into the grid is a double-edged sword. While it brings clean energy, it also introduces complexities that can challenge the grid’s stability. A recent study led by Xu Tian from the School of Mechanical and Electrical Engineering at China University of Mining and Technology-Beijing, published in IEEE Access, has shed light on one of these challenges: transient overvoltage in direct-drive wind turbine generators connected to weak power systems. This phenomenon, which occurs during the restoration phase after an AC short-circuit fault, can significantly impact the secure and stable operation of the grid.
The research establishes a mathematical model for the grid-connected system of direct-drive wind turbine generators, deriving the expression of the terminal current and considering the impact of the inner current control loop. This leads to a specific expression for transient overvoltage, allowing for a comprehensive analysis of various influencing factors. “A smaller short-circuit ratio results in a larger voltage drop and reactive current increment, which in turn leads to a higher transient overvoltage,” Tian explains. This finding is crucial for understanding how the grid’s robustness can be affected by the integration of wind power.
The study also reveals that a slower active power recovery rate corresponds to a slower overvoltage recovery speed. This insight is particularly important for grid operators and wind turbine manufacturers, as it highlights the need for optimized control parameters to mitigate the amplitude and recovery speed of fault recovery overvoltage under various short-circuit ratios. “By optimizing these parameters, we can enhance the stability of the grid and ensure a smoother recovery from faults,” Tian adds.
The implications of this research are far-reaching. As the world continues to shift towards renewable energy sources, the integration of wind power into the grid will only increase. Understanding and mitigating transient overvoltage is therefore critical for maintaining grid stability and reliability. The proposed analytical control parameter optimization method could shape future developments in the field, leading to more robust and resilient grid systems.
The study’s findings were substantiated through a simulation model developed within the PSCAD/EMTDC platform, confirming the accuracy of the transient overvoltage formulation and the effectiveness of the proposed mitigation method. This research not only advances our understanding of transient overvoltage but also provides practical solutions for the energy sector. As we continue to harness the power of the wind, studies like this one will be instrumental in ensuring a stable and secure energy future.
