虚拟同步控制的暂态特性优化策略研究

Research on Transient Characteristic Optimization of Virtual Synchronization Generator Control Strategy

虚拟同步控制策略具有降低功率暂态响应最大频率偏差的优势。但在指令功率或电网频率出现扰动时,虚拟惯量的引入会造成较大的暂态功率振荡和超调。与真实的同步发电机不同,虚拟同步控制策略可以灵活地改变控制结构及其相关参数以改善系统的暂态性能。该文提出2种基于电网频率参与虚拟惯量功率控制的改进虚拟惯量策略:电网频率估计策略和电网频率前馈策略。并根据响应特性能给出详细的参数设计方法。此外,对比研究2种策略在功率指令扰动和电网频率扰动工况下的暂态功率和频率的响应特性。仿真与实验结果表明,与传统方法相比,2种改进策略均能提高虚拟同步的暂态性能。

Virtual synchronous generators(VSGs) have the advantage of reducing the maximum frequency deviation of the power reference step response, but there is a risk of increasing power oscillation and overshoot, which is disadvantageous for easily damaged grid-connected converters. Unlike real synchronous generators, VSGs can modify their parameters and control structures flexibly to enhance their transient response performance. Therefore, this paper proposed two virtual inertial control strategies based on grid frequency information, and gave out the corresponding parameter design methods. In addition, the transient power response and transient frequency response under typical disturbance conditions of power reference and grid frequency were compared. The simulation and experimental results show that compared with traditional method, both modified strategies can improve VSG transient performance.