基于阻尼转矩分析法的光伏发电系统小信号建模分析

Small-signal Stability Analysis of Photovoltaic Power Generation System Based on Damping Torque Analysis Method

光伏发电系统的动态特性是分析其对系统影响的关键。本文在对光伏发电系统小信号模型特征分析的基础上,从阻尼转矩分析的角度解释了光伏发电系统阻尼成因,推导了无功电流内环模式的性质判定条件,结合特征值轨迹分析了系统特征模式随参数变化的规律,并依此优化设计了系统控制参数。研究表明:与同步机动力学阻尼类似的电气阻尼现象决定了光伏发电系统阻尼;系统等效阻尼系数和等效同步系数及各状态变量间的耦合关系决定了模式的性质。根据阻尼转矩分析优化选取系统控制参数可增强系统阻尼,改善系统受扰暂态性能。

The dynamic characteristic of photovoltaic （PV）power generation is the key to the analysis of its impact on power system. The conventional damping torque analysis （DTA）is carried out to study the generation mechanism of damping based on a small-signal model of PV generation. Furthermore, the judging criteria for the nature of reactive current inner loop pattern is derived, and how the characteristic patterns of the system vary with parameters is analyzed based on eigenvalue trajectory, thus the optimal system parameters are designed accordingly. It is shown that electric damping, which is similar to the dynamic damping of synchronous generator, leads to the damping of PV generation. The equivalent damping coefficient, equivalent synchronous coefficient, and the coupling relationship among state variables determine the nature of the pattern. The system damping can be intensified with the selection of optimal parame- ters by DTA, which can further improve the transient performance of the system.