基于虚拟同步机的微电网频率稳定控制研究

Research on Frequency Stability Control for Micro-grid Based on Virtual Synchronous Generator

大量电力电子设备接入下的微电网,由于缺少必要的惯性储备,将加剧系统因故障扰动、孤网运行等带来的频率不稳定问题。为解决该问题,可模拟传统同步机的运行特性,在逆变器控制中加入惯性和阻尼环节。根据上述思想,本文基于传统同步机摇摆方程,建立了虚拟同步机控制模型,分析了该控制策略下系统的动态特性,重点研究了不同阻尼系数下的虚拟同步控制器对系统频率稳定性的影响,并根据控制需求,提出了变阻尼系数控制的方法。通过Simulink仿真和硬件在环实验,验证了所提方法的正确性和可行性;最后,对比了传统PQ控制及下垂控制下系统的频率稳定性,显示了该控制方法的优越性。

Since a large number of power electronics accessed to the micro-grid,which causes the lack of inertial reserves,the frequency stability issue may arise due to the fault disturbance and isolated operation.To solve this problem,the operating characteristics of the traditional synchronous machine can be simulated by adding inertia and damping in the inverter control.According to the above ideas,a virtual synchronous generator model is built based on swing equation in this paper,the dynamic characteristics of the system are analyzed,and the influence of the virtual synchronization controller with different damping coefficients on the system frequency stability is mainly studied.According to the control requirements,a variable damping coefficient control method is proposed.The simulation and hardware in-the-loop experiments have verified the correctness and feasibility of the proposed method.In the end,the traditional PQ control and the system frequency stability base on droop control are compared,which shows the superiority of proposed control method.