永磁同步风电机组机侧直流阻抗建模

永磁同步风电机组因其具有单机容量大、发电效率高、控制性能好等优势,在海上风电场中占有较高比例。在海上风电场直流外送系统中,永磁同步电机风电场采用直流汇集方式,然后经高压直流线路送出,可以减少电能变换次数,从而减少设备数量、节约海上平台建造所需人力物力,因此直流海上风电场成为一种研究趋势。因为多机组串联时单机组故障易引发系统崩溃,直流海上风电场外送系统对于风电机组和系统稳定性具有较高要求。阻抗模型已逐步成为广泛采用的稳定性分析方法,作为直流海上风电场的基本组成单位,永磁同步风电机组直流端口阻抗模型尚未建立。基于谐波线性化方法建立永磁同步风电机组机侧模型的直流端口阻抗模型,并对不同转速条件下的阻抗模型进行仿真验证。最后开展机组阻抗特性分析研究,详细分析了转速以及电流环控制特性对机组直流阻抗特性的影响,为后续直流海上风电场外送系统稳定性分析奠定模型基础。

DC Impedance Modeling of PMSG Wind Turbines Machine-side Model

Due to the large capacity,high power generation efficiency,and good control performance,permanent magnet synchronous generators(PMSGs)account for a higher proportion in offshore wind farms.In the DC delivery system of offshore PMSG wind farms,the power generated by wind turbines are collected at the DC bus and then sent out through the high-voltage DC transmission,in this way the frequency of power conversion can be reduced,so as to decrease the number of equipment and the cost of the offshore platform.Thus the DC offshore wind farms have become a research trend.However,because that the failure of single turbine will result into the system collapse when multiple turbines are connected in series,the DC offshore wind farm delivery system has higher requirements for the stability of wind turbine and system.Impedance model has gradually become a widely used analysis method for the power system stability.As the basic unit of DC offshore wind farm,the DC impedance model of PMSG wind turbines was not established yet.Based on the harmonic linearization method,the DC port impedance model of the PMSG machine-side model was established,and the impedance model under different speed conditions by simulation was verified.Finally,the impedance characteristics of the wind turbines were analyzed,and the influence of rotor speed and current loop control characteristics on the DC impedance characteristics was analyzed in detail,which lays a model foundation for the stability analysis of the DC offshore wind farm.