基于嵌合转矩法的虚拟同步机多回路保结构稳定分析

虚拟同步发电机(virtual synchronous generator,VSG)控制系统结构复杂、耦合性强,传统的稳定性分析方法无法分析系统内部各交互回路间的相互作用机理问题。基于此,文章提出一种基于嵌合转矩法的多回路保结构稳定分析方法。首先,基于模块化建模思想及模块重构建立了VSG并网的多回路交互保结构模型;其次,基于嵌合转矩法建立各交互回路间的回路阻尼转矩,形成分析-结构联通对应关系;然后,详细分析多回路系统中关键回路和关键参数的精确溯源方法,对VSG系统内各环节间的阻尼竞争及互激等规律进行了深入分析;最后,以VSG控制下的单机无穷大系统为例进行仿真验证。结果表明:VSG控制系统中电压控制环和电流控制环的直轴分量和交轴分量存在交互影响。其交互回路间阻尼转矩的恶性竞争以及负向激励导致了系统机电振荡模式失稳。该方法在捕捉系统失稳机制的基础上,还能为实际参数配置优化提供借鉴基础,具有一定应用价值。

Stability Analysis of Multi-loop Guarantee Structure of Virtual Synchronous Machine Based on Chimeric Torque Method

Virtual synchronous generator(VSG)control system has complex structure and strong coupling.Traditional stability analysis methods can not analyze the interaction mechanism among the interaction loops in the system.Based on this,this paper proposes a multi-loop structural stability analysis method based on chimeric torque method.Firstly,based on the idea of modular modeling and module reconstruction,the multi-loop protection structure model of VSG grid-connected is established.Secondly,loop damping torques of each interactive loop were established based on chimeric torque method to form the analysis-structure connectivity correspondence.Then,the precise traceability method of the key loop and key parameters in the multi-loop system is analyzed in detail,and the rules of damping competition and mutual excitation among all links in the VSG system are deeply analyzed.Finally,a single infinite machine system under VSG control is taken as an example for simulation.The results show that the direct axis components and quadrature axis components of voltage control loop and current control loop in VSG control system interact.The vicious competition and negative excitation of the damping torque between the interaction loops lead to the instability of the electromechanical oscillation mode.This method not only captures the instability mechanism of the system,but also provides a reference basis for the actual parameter configuration optimization,which has a certain application value.