虚拟同步发电机并联运行的阻抗匹配策略

Impedance Matching Strategy for Parallel Virtual Synchronous Generators

在逆变器中加入转动惯量和阻尼,实现虚拟同步发电机(VSG)控制,可在兼顾本地负载平滑切换的同时提高交流母线频率稳定性。VSG并联按其容量配比对负载进行合理分配,但阻抗不同会对并联造成稳态误差,同样会影响动态性能。提出一种基于虚拟阻抗的并联VSG控制方法,对励磁环节进行改进,实现对交流母线电压的控制,分析有功功率和无功功率运行特性;加入虚拟阻抗并得出阻抗匹配原则,分析虚拟阻抗在暂态过程中的效果。在MATLAB/Simulink中和实验台架上进行了两台VSG并联仿真和实验,结果表明,提出的控制策略可以抑制投切过程中的频率波动,提高VSG并联的稳定性。

The virtual synchronous generator（VSG）control can be realized by adding inertia and damping in the inverter,which can improve the stability of the AC bus frequency while considering the smooth switching of the local load.The load of parallel VSG can be distributed reasonably according to its capacity ratio,but the different impedances will cause steady-state error of parallel system,and also affect its dynamic performance.To solve this problem,aparallel VSG control method based on virtual impedance is proposed.Firstly,the improved excitation is proposed which can control the AC bus voltage,and operation characteristics of active power and reactive power are analyzed.Secondly,the impedance matching principle is obtained while adding the virtual impedance,and the effect of virtual impedance in transient process is analyzed.Finally,the proposed control strategy is verified in the environment of MATLAB/Simulink and the experimental platform.The results show that the proposed strategy can inhibit the frequency fluctuation in cutting process and improve the stability of VSG parallel system.