大规模双馈风电机组并网频率稳定控制策略

风电在电网中的渗透率逐年升高，尽管其在优化电源结构、节能减排方面有颇多贡献，但是由于自然风的波动性和不确定性，大规模风电并网势必会对电网频率稳定等方面产生影响。针对此问题，对装机量较高的双馈型风力发电机组（doubly-fed induction generator，DFIG）控制系统进行研究，制定大规模双馈型风电机组并网下的频率稳定控制策略。在现有附加下垂控制及虚拟惯性控制的基础上，根据输入风速以及电网侧频率波动，对下垂控制环节进行变系数处理，改善下垂控制特性。将DFIG运行工况进行分类，并采用变减载系数，使DFIG在限功率运行的同时减少弃风。采用具有大规模风电并网接入的实际电网模型，仿真验证了所提频率稳定控制策略的有效性。

Frequency Stability Control Strategy for Large-scale Grid Connections with DFIG Units

The penetration rate of wind power in the power grid has been increasing year by year. A lot of contributions have been made to optimize the power supply structure, energy conservation and emission reduction, however, due to the natural fluctuation and uncertainty of wind speed, grid integration with large-scale wind power is bound to impact the frequency stability of the power grid. With regard to this problem, the doubly-fed induction generator (DFIG) control system was studied in this paper and then the primary frequency modulation control strategy following large-scale DFIG connection was established. On the basis of the existing droop control and virtual inertia control strategy, the droop control part is implemented by virtue of variable coefficient according to the input wind speed and the frequency fluctuation of grid side, as to improve the droop control characteristics. Additionally, the operating conditions of DFIG are classified, and the load reduction coefficient is used to reduce the curtailment of wind while the DFIG is running at limited power level. The effectiveness of the proposed primary frequency modulation control strategy is verified by means of the simulation of an actual power grid model with large-scale wind power grid connection.