大规模双馈风电机组参与调频的电网自适应低频减载策略

大规模风电参与惯性控制和一次调频会对电网频率特性产生显著影响，而现有的低频减载方法尚未考虑该影响，可能引起频率轨迹失真和负荷切除不合理问题。鉴于此，以双馈型风电机组为例，研究将风电虚拟惯性响应时变特性参数和一次调频响应系统模型融入低频减载过程的方法，提出了改进低频减载策略和负荷切除决策模型。首先，通过求解含风电虚拟惯性响应的电网等效惯量(具有时变特性)、检测频率变化率，计算低频减载首轮起动时刻的实时功率缺额。然后，定量表征风电一次调频及负荷调节效应先抵消部分的实时功率缺额，剩余功率缺额则由自适应低频减载策略分批切除。最后，理论研究及算例分析结果表明，所提低频减载改进策略和模型能更客观地反映电网频率特性，负荷切除量明显更小，体现了大规模风电参与调频对低频减载的有益影响。

Adaptive Under-frequency Load Shedding Strategy of Power Grid with Large-scale DFIG Wind Turbines Participating in Frequency Regulation

The frequency characteristics of power grid will be notably impacted by large-scale wind power participating in inertial control and primary frequency regulation(PFR). These factors, which may cause frequency trajectory distortion and unreasonable load shedding, have not been considered in the existing under-frequency load shedding(UFLS)methods. Therefore, taking doubly-fed induction generator(DFIG)wind turbines as an example, the method for integrating the inertial response time-varying characteristic parameters and the PFR response system model into the process of UFLS is studied. Meanwhile, an improved UFLS strategy and load resection decision are proposed. Firstly, by solving the grid equivalent inertia(contain the virtual inertial response of wind farm)with time-varying characteristics and detecting the rate of change of frequency, the real-time power shortage is calculated at the first-time starting moment of UFLS. Then, some shortages of real-time power are offset by quantitatively characterizing the PFR of wind power and the effect of loads regulation, and the remaining power deficit is removed by an adaptive UFLS strategy. Finally, it can be observed from the theoretical research and simulations that the frequency characteristics of the grid can be reflected more objectively by using the proposed UFLS improvement strategy, and the amount of load removal is much smaller. This phenomenon reflects the beneficial effects of large-scale wind power participating in frequency regulation on UFLS.