基于变参数减载控制的风电场一次调频策略

变速恒频风机通过电力电子设备实现并网，导致机组转速与系统频率不再有耦合关系，无法主动响应系统频率变化。针对风电大规模并网引发的系统调频安全问题，采用优先减载低风速机组的风电场预留备用策略，并结合桨距角控制，实现满足系统备用需求，同时最大限度地储存旋转动能；然后提出了变调频系数的虚拟惯量控制策略，给出了下垂系数的整定方法，以实现风机减载功率充分释放，为系统提供可靠的调频功率支持。在DIgSILENT中建立了系统仿真模型，结果表明：所提策略能够合理分配风机的减载功率，并有效利用备用容量参与系统调频，提升了风机的频率控制能力。

Primary Frequency Control Strategy for Wind Farms Based on Variable Parameter De-loading Control

Variable speed constant frequency (VSCF) wind turbines are connected to the grid through power electronic equipment, leading to the decoupling of wind turbine’s rotor speed and system frequency. As a result, the wind turbines cannot actively respond to the changes of system frequency. To cope with the system frequency stability problem resulting from large-scale integration of wind power, a new active power control strategy for wind farms is proposed, which preferentially applies overspeed de-loading control to wind turbines operating in low wind speed zone. Accordingly, the kinetic energy stored in the rotating mass of wind turbines can be maximized. In the meantime, the reserve demand of the system required by the transmission system operator can be met by applying pitch angle control to wind turbines operating in high wind speed zone. Furthermore, a virtual inertial control strategy with variable parameters is proposed, and the droop coefficient is tuned to ensure the full release of the reserve power of the wind turbines during the system frequency regulation. A system simulation model is built in the DIgSILENT, and the simulation results show that the proposed strategy can reasonably allocate the reserve power of wind turbines and effectively use the reserve power to respond to the frequency change of the system, thus improving the frequency control capabilities of the wind turbines.