惯量–刚度补偿器增强接入弱电网风电场直流电压时间尺度小干扰稳定的作用机理分析

Mechanism Analysis of Stability Improvement of Wind Farm Connected Into Weak Grid by Inertia-stiffness Compensator in DC-link Voltage Time Scale

以风力发电代表的新能源发电大规模接入电网,其物理和控制结构与传统同步发电机不同,多质量块多闭环反馈控制会引起更复杂的振荡模态,引发频域更宽、更复杂的稳定问题。该文分析一种新型电力电子装备:惯量–刚度补偿器对含大规模风电电力系统直流电压时间尺度小干扰稳定性的作用机理。该文首先以全功率风电机组为例介绍弱电网中风电机组直流电压时间尺度动态特性,推导直流电压时间尺度风电机组小信号模型并利用转矩法分析其小干扰稳定性;而后介绍惯量–刚度补偿器的基本结构和控制;然后建立弱电网下包含惯量–刚度补偿器与风电机组小信号模型,并分析直流电压时间尺度的小干扰稳定性;最后利用复转矩系数法分析惯量–刚度补偿器对直流电压时间尺度同步和阻尼功率分量的影响。理论分析和仿真结果验证了惯量–刚度补偿器对增强弱电网下风电场、风电机群直流电压时间尺度小干扰稳定性的有效性。

Large-scale wind power generation has been connected to the power grid,whose physical and control structure is quite different from the traditional synchronous generator,thus leads to more complicated oscillation mode and stability problem.In this paper,the effect mechanism of a new kind of power electronic equipment-inertia-stiffness compensator(ISC)on the DC-link voltage time scale small-disturbance stability was presented.Firstly,the dynamic characteristics of the DC-link voltage time scale of the wind turbine connected into the weak grid with long transmission line were analyzed.The small signal model of the DC-link voltage time scale was deduced and its small-disturbance stability was studied.Then,the basic structure and control of ISC were introduced.Furthermore,the small signal model of ISC and wind turbine under weak grid was established,and the small-disturbance stability of DC-voltage time scale was analyzed.Finally,the complex torque coefficient approach was used to analyze the influence of ISC on the wind turbine’s synchronization and damping components in the DC-voltage time scale.Theoretical analysis and simulation results verify the effectiveness of the ISC in enhancing the DC-link voltage time-scale stability of wind farms connected into the weak grid.