考虑惯性调频的双馈风电机组主动转速保护控制策略

双馈风电机组模拟惯性调频能响应系统频率变化、缓解大规模风电并网导致的系统惯性降低问题。但是转子储存动能有限,当转子转速下降到一定限值时风电机组将退出调频并恢复转速,这将引起系统频率二次跌落。文中首先对双馈风电机组在不同风速区内的惯性调频特性进行了分析,并量化分析了不同风速区内风电机组参与调频过程中的有效释放动能,然后提出了基于动能损失负反馈的主动转速保护控制策略。该策略根据双馈风电机组容量和实时运行工况调整转速保护控制器的比例—积分系数,使双馈风电机组随着转子转速下降逐渐退出调频过程,从而维持风电机组在释放动能过程中自身的稳定性,避免频率二次跌落。不同风速区内仿真结果验证了所提主动转速保护控制策略的有效性。

Active Rotor Speed Protection Strategy for DFIG-based Wind Turbines with Inertia Control

Doubly-fed induction generator (DFIG)-based wind turbines with virtual inertia control can contribute to the primary frequency regulation and relieve the lack of system inertia caused by high penetration of large-scale wind farms. However, DFIG-based wind turbines will exit frequency regulation if the rotor speed falls below a definite value since the kinetic energy stored in the rotor is limited. This procedure and the subsequent rotor speed recovery will lead to a secondary frequency drop. The characteristics of virtual inertia control and available kinetic energy released by DFIG-based wind turbines under different wind speed conditions are quantitatively analyzed. Then an active rotor speed protection strategy is proposed to make DFIG-based wind turbines gradually release the kinetic energy to avoid the secondary frequency drop. In the proposed strategy, a negative feedback control is adopted to release rotor kinetic energy, and its proportional and integrated parameters are set adaptively according to the operational states and capacity of the DFIG-based wind turbines. The validity and effectiveness of the proposed protection strategy is illustrated by case studies.This work is supported by National Natural Science Foundation of China (No. 51477093, No. 51277112).