基于低阶频率响应模型的双馈风电机组下垂系数修正方法

在频率下垂控制期间,由于减载备用曲线运行点会随转子转速变化而发生偏移,造成双馈风电机组实际贡献的一次调频能力低于设定期望值。为了解决这一问题,首先根据小信号分析理论建立了由双馈风电机组与火电机组构成的分布式系统低阶频率响应模型。然后利用该模型分别推导出评估双馈风电机组实际与期望一次调频能力的量化计算式,提出将设定的下垂系数乘以一个缩小因子后,可使双馈风电机组贡献出期望一次调频能力。最后选用某实际分布式系统对提出的下垂系数修正方法进行了有效性验证,仿真结果表明,当双馈风电机组采用所述方法进行下垂系数修正后,不仅能使系统准稳态频率偏差达到期望水平,还进一步改善了系统最大频率偏差。

Droop Coefficient Modification Method for DFIG Based on Low-order System Frequency Response Model

Owing to the fact that the operating point on the de-loading power curve will shift when the actual rotor speed changed during the frequency droop control, doubly-fed induction generators(DFIG)cannot provide the desired primary frequency control ability. To solve this problem, firstly a novel low-order system frequency response model is established for distributed systems including DFIG and thermal generation unit based on the small signal analysis theory. And then the quantified formulas of the actual and desired primary frequency control abilities of DFIG are derived by using the proposed model. According to the derivation, this paper proposes that DFIG provide the desired primary frequency control ability after multiplying a reduction factor for the original set of droop coefficients. Finally, the capability of the proposed droop coefficient modification method is tested on an actual distributed system. The simulation results show that, with the proposed method, not only has the system quasi-steady-state frequency deviation reached the expectation level, but also the system maximum frequency deviation has further improved.