基于功率跟踪优化的双馈风力发电机组虚拟惯性控制技术

基于电力电子换流器并网的变速恒频风力发电机组对电力系统的惯性几乎没有贡献,这将成为风电场大规模接入电网之后面临的新问题。在分析双馈风电机组运行特性和控制策略的基础上,研究双馈机组的虚拟转动惯量与转速调节及电网频率变化的关系,提出双馈风电机组的虚拟惯性控制策略。该控制策略通过检测电网频率变化来调节最大功率跟踪曲线,从而释放双馈机组"隐藏"的动能,对电网提供动态频率支持。通过对含20%风电装机容量的3机系统的仿真分析,验证该控制策略在系统出现功率不平衡后,能够利用双馈风电机组的虚拟惯量使风电场具备对系统频率快速响应的能力,从而提高了基于双馈风电机组的大规模风电场接入电网后的电力系统频率稳定性。

Virtual Inertia Control of DFIG-based Wind Turbines Based on the Optimal Power Tracking

The increasing penetration of large-scale wind generation in power system will bring a new challenge that the converter based variable speed wind turbines has no contribution to the power system inertia.In this paper,the operation characteristics and control scheme of the doubly fed induction generator(DFIG) was analyzed firstly,and then the relationship between the virtual inertia,the rotor speed regulation and the network frequency variation was investigated.Finally,a novel virtual inertia control strategy of the DFIG based wind turbines was proposed.The proposed strategy can change the maximum power point tracking(MPPT) curve according to frequency deviation monitoring,so as to release the "hidden" kinetic energy and provide dynamic frequency support to the grid.A three-machine system with 20% wind power penetration was used to validate the proposed control strategy.The simulation results show that the DFIG-based wind farms have fast respond ability to the grid frequency deviation caused by the active power disturbances using the virtual inertia control,so that the frequency stability of the power system with large wind power integration is improved.