虚拟同步发电机多机并联系统的频率小信号稳定性分析研究

Research on Frequency Small-signal Stability Analysis of Multi-parallel Virtual Synchronous Generator-based System

不同于虚拟同步发电机(virtual synchronous generator,VSG)单机并网系统,VSG多机并联并网系统中各设备间有着更为复杂的相互作用关系,所以仅利用传统的分析方法很难准确地分析出系统的动态性能。为了分析VSG本体、VSG与VSG之间以及VSG与电网之间的频率特性,该文首先推导VSG多机并联并网系统的通用小信号模型。其次,结合系统特征根主导状态变量的参与因子运动轨迹,详细地分析线路连接阻抗、输出功率大小和有功控制环参数等因素对系统低频特征根的影响关系,以此得出系统参数对VSG本体、VSG与VSG之间以及VSG与电网之间的频率影响规律。最后,在不同工况下通过仿真验证该文所得系统频率稳定性影响规律的正确性.

Different from the single virtual synchronous generator(VSG)-based grid-connected systems,the multi-parallel VSG-based grid-connected systems have more complex interactions between devices.Consequently,the traditional analysis method cannot analyze the dynamic stability performance of the system accurately.In order to study the frequency characteristics of the VSGs and power grid,this paper firstly derived the general small-signal model of the multi-machine parallel VSG-based system.Secondly,combined with the participation factor locus of the state variables of the system eigenvalues,the influences of the line impedance,the output power and the parameters of the active control loop on the eigenvalues of the low frequency band were analyzed in detail.In this way,the influence of parameters on the frequency of VSGs and power grid were obtained.Finally,the correctness of the investigated influence law on the system frequency stability was verified by simulation under different working conditions.