Effect of Low Pass Filter in Governor Model of Virtual Synchronous Generator

In a typical ac power system, the grid frequency reflects the balance between grid total power generation and its total power consumption. With more renewable energy sources fed through power electronics converters (PECs) connected to the grid, their controllers are adapted to incorporate virtual inertia loops to help maintain the grid inertia originally provided by synchronous generators (SG). Such converters are referred to as virtual synchronous generators (VSGs). Virtual synchronous generator-based control consists of three main blocks: governor model, virtual inertia control loop and automatic voltage regulator. Among them, governor model block is mostly overlooked. This work investigates the effect of its low pass filter (LPF) on microgrid (MG) large signal stability. A mathematical model of a virtual inertia controller, including LPF, is first introduced. As the model becomes non-autonomous, this study relies on a geometrical approach to demonstrate its impact rather than analytical one. A case study of a LPF with different time delays (bandwidth) is conducted to show its impact on VSG large signal dynamics.