基于双馈风电机组频率响应解析模型的系统低频减载策略

Under-frequency Load Shedding Strategy for Power System Based on Analytical Frequency Response Model of Doubly-fed Wind Turbines

规模化双馈风电机组主动参与系统频率响应对其动态和稳态特性均产生显著影响,然而,目前低频减载策略研究对该影响认识并不清晰且考虑不够充分。为此,提出了考虑双馈风电机组参与频率调节的电网低频减载策略和负荷切除决策模型。首先,根据与定子磁链定向的矢量控制方法,推导了双馈风电机组综合惯量控制的线性化解析模型。进而,分析并阐述了双馈风电机组综合惯量控制对低频减载切负荷量的影响,定量表征了双馈风电机组参加频率调节所抵消的部分功率缺额,进而确定了低频减载切负荷决策量。最后,通过算例证明,所提线性化解析模型能够准确刻画双馈风电机组的频率响应特性,且改进的低频减载策略能够在保证频率安全的前提下,减少切负荷量,充分验证了双馈风电机组参与频率响应的稳态功率支撑价值。

The active participation of large-scale doubly-fed wind turbines in the frequency response of the system makes a significant impact on its dynamic and steady-state characteristics.However,current studies on the under-frequency load shedding(UFLS)strategies do not have a clear understanding and full consideration of the impact.Therefore,an UFLS strategy and a load shedding decision-making model for the power system considering doubly-fed wind turbines participating in frequency regulation are proposed.Firstly,Based on the vector control method oriented towards stator flux,a linearized analytical model for the comprehensive inertia control of doubly-fed wind turbines is derived.Furthermore,the impact of comprehensive inertia control of doubly-fed wind turbines on the load shedding amount of UFLS is analyzed and elaborated,which quantitatively characterizes the partial power shortfall offset by the participation of doubly-fed wind turbines in frequency regulation,thereby the load shedding decision quantity of UFLS is determined.Finally,through numerical cases,it has been proven that the proposed linearized analytical model can accurately characterize the frequency response characteristics of doubly-fed wind turbines,and the improved UFLS strategy can reduce load shedding amount while ensuring frequency safety,fully verifying the steady-state power support value of doubly-fed wind turbines participating in frequency response.