新能源并网变换器单机无穷大系统的静态稳定极限及静态稳定工作区

The Static Stable-limit and Static Stable-working Zone for Single-machine Infinite-bus System of Renewable-energy Grid-connected Converter

针对基于输出电流闭环控制的新能源并网变换器,研究弱电网条件下其输出有功功率特性,推导其在直流电压时间尺度下的数学模型,基于输出有功功率特性和直流电压时间尺度下的数学模型得到新能源并网变换器单机无穷大系统的静态稳定判据,在此基础上进一步给出新能源并网变换器单机无穷大系统的静态极限电流、静态极限功角与电网阻抗及无功电流之间的关系。通过Matlab/Simulink仿真对新能源并网变换器单机无穷大系统在不同工作点的静态稳定性进行验证。最后,对比新能源并网变换器与同步发电机特性的异同。

Aiming at the renewable-energy grid-connected converter based on the closed-loop control of output current, the output active power characteristics under weak grid condition were studied, and the mathematical model of DC-link time-scale was derived. Based on the output active power characteristics and the mathematical model of the DC-link time-scale, the static stability criterion for the single-machine infinite-bus system(SMIB) of renewable-energy grid-connected converter was obtained. Moreover, the relationships of the static limit current, the static limit power-angle respect to the grid impedance, and reactive current were further derived. The static stability under different working points for the renewable-energy grid-connected converter was verified by Matlab/Simulink simulation. Finally, the similarities and differences between the renewable-energy grid-connected converter and the synchronous generator were compared.