考虑轴系扭振抑制的双馈风电机组惯量控制策略

Inertia control strategy of doubly fed induction generators considering torsional vibration suppression

双馈风电机组惯量控制是通过建立发电机转子转速与电网频率之间的耦合关系,调整机组有功输出以适应电力系统频率波动。惯量控制直接快速地调节有功会对机组轴系小干扰稳定性造成负面影响,不利于轴系扭振的抑制。文章分析了不同惯量控制响应特征及其对轴系阻尼特性的影响,设计一种以转差率为输入信号的附加惯性与阻尼转矩的惯量控制策略,提出了含轴系稳定性约束的附加惯性与阻尼转矩惯量控制参数整定方法。仿真结果表明,所设计的双馈风电机组惯量控制策略不仅有良好的惯量控制效果,还能有效增大轴系等效电气阻尼,提高了轴系的稳定性。

Inertia control schemes are commonly used to improve the initial frequency response of variable-speed constant-frequency wind generators, through establishing a relationship between rotor speed and grid frequency to adjust the unit active power output. However, the fast and direct power regulation in inertia control will not only have the second frequency dip problem, but also impact negatively on shaft small disturbance stability. Taking doubly-fed induction generator(DFIG)-based wind turbine as an example, the inertia control mechanisms, inertia response characteristics and control’s impacts on shaft damping of different inertia control schemes are analyzed. Then, an improved inertia and damping supplementary(IDS) inertia control scheme is put forward. Through calculating the equivalent inertia time constant and the shaft equivalent electrical damping quantitatively, the objective function of IDS control optimization model is established and so the parameters are determined. Case studies verifies the frequency support effects and the damping improvement effects of the proposed inertia strategy.