基于混合参考阻抗法的风电场谐波发射水平评估

风电逆变器的LCL滤波器和风电场的无功补偿设备致使风电场侧谐波阻抗并非远大于系统侧谐波阻抗,因此在评估风电场PCC点两侧的谐波发射水平的同时必须考虑PCC点两侧谐波阻抗。对此,提出一种基于混合参考阻抗的风电场谐波发射水平评估方法。系统侧谐波阻抗仅通过测量数据评估得出,风电场侧的参考谐波阻抗值通过风电场内元件的参数计算得出。针对LCL滤波器参数的难以获取性,提出一种LCL滤波器参数估计方法,并考虑元件参数的变化,计算出风电场侧谐波阻抗的边界值,并以其平均值作为风电场侧谐波阻抗的参考值。最后通过仿真和实测数据分析验证了本文方法的有效性。研究成果可为风电场谐波发射水平评估提供参考。

Assessment of Harmonic Emission Level of Wind Farm Based on Mixed Reference Impedance

The LCL filters of wind power inverters and the reactive power compensation equipment of wind farm make the harmonic impedance of wind farm side is not much larger than that of the utility side, so the harmonic impedance on both sides of the PCC point must be taken into account when assessing the harmonic emission levels on both sides of the PCC point of wind farm. A method based mixed reference impedance was proposed for assessing the harmonic emission value of wind farm. The harmonic impedance of utility side was evaluated only by measurement data. The reference harmonic impedance was calculated by the parameters of wind farm. For the difficulty of obtaining the parameters of the LCL filter, a method for estimating the parameters of LCL filter was proposed, and the change of the parameters was take into account to calculate the boundary value of harmonic impedance of wind farm side, whose average value was take as the reference impedance of wind farm. Simulation and field data verify the effectiveness of the proposed method. The research results can provide reference for the assessment of harmonic emission level of wind farm.