基于运行短路比的新能源场站中跟/构网可切换单元的最优配置方法

Optimal Configuration of Grid-following/Grid-forming Switchable Units in New Energy Stations Based on Operating Short-circuit Ratio

现有新能源场站中的发电单元基本采用跟网控制,难以在极弱电网下保持安全稳定运行。在发电单元全采用跟网控制的新能源场站内配置少量跟/构网可切换发电单元,可提升场站在弱网下的运行能力,避免失稳问题。首先建立跟/构网可切换单元模型,实现无扰切换。其次,分析了新能源发电单元在跟/构网控制下的稳定特性,进而选取运行短路比并作为跟/构网切换指标。再次,提出基于运行短路比的新能源场站跟/构网切换方案,并提出了跟/构网可切换单元最优配置方法。最后,通过算例仿真验证了所提配置方法的合理性和优越性。

The existing new energy stations based on the traditional grid-following control can hardly adapt to the weak grid.Retrofitting some units with a grid-following/gridforming switching function can enhance the station’s operation capability with a weak grid and avoid the problem of sub-synchronous oscillation.Firstly,this paper establishes a network switching model to achieve an undisturbed switching of grid-following and grid-forming.Secondly,this paper analyzes the stability characteristics of the new energy power unit under the grid-following and grid-forming control,and then the operating short circuit ratio is chosen as the switching index of the grid-following/grid-forming control.Thirdly,a new energy station switching scheme based on the operating short circuit ratio is proposed,and the optimal configuration method of the switchable unit is proposed.Finally,the rationality and superiority of the proposed configuration method are verified by simulation examples.