双馈风电并网对电力系统频率响应的影响

Effects of DFIG Wind Power Grid-connection on Frequency Response of Power System

与传统同步发电机不同,双馈风机DFIG(doubly-fed induction generator)并网具有柔性连接特性,实现了输出功率与电网频率的解耦。为分析风电渗透率的提高给电力系统频率稳定带来的问题,本文提出了一种关于DFIG并网对系统惯量水平和频率响应过程影响的分析方法。首先基于同步发电机的转子运动方程,针对风电接入改变原有同步机出力或者替换部分同步机的不同形式,推导出了DFIG并网对系统等值惯性时间常数影响的关联关系。在此基础上,结合考虑同步机和负荷的频率调节特性,通过建立电力系统频率响应模型,理论分析了DFIG并网等因素对系统频率响应过程的影响。在Matlab/Simulink仿真平台建立模型,结合算例对理论分析过程和结果的正确性进行了验证。

Different from the traditional synchronous generator,the grid-connection of doubly-fed induction generator(DFIG)has characteristics of flexible connection,which realizes the decoupling of output power and grid frequency.The increase in wind power penetration rate will affect the frequency stability of a power system.To solve this problem,a method is proposed to analyze the effects of DFIG grid-connection on the system’s inertia level and frequency re⁃sponse process.First,aimed at different forms of changing the output from the original synchronous generator or replac⁃ing part of the synchronous machine,the effects on the system’s equivalent inertia time constant due to DFIG grid-con⁃nection are derived based on the rotor motion equation of the synchronous generator.On this basis,combined with the frequency regulation characteristics of synchronous machines and load,the frequency response model of power system is established,through which the effects of DFIG grid-connection and other factors on the system’s frequency response process are analyzed theoretically.This model is built on the MATLAB/Simulink simulation platform,and the theoreti⁃cal analysis process and results are verified by an example.