Oscillation Damping of a Distributed Generator Using a Virtual Synchronous Generator

These days, distributed generators (DGs), such as photovoltaic, wind turbine, and gas cogeneration systems have attracted more attention than in the past. DGs are often connected to a grid by power inverters. The inverters used in DGs are generally controlled by a phase-locked loop (PLL) in order to be synchronized with the grid. In a stability point of view, the power system will be significantly affected if the capacity of inverter-based DGs becomes larger and larger. The concept of the virtual synchronous generator (VSG), which is used to control inverters to behave like a real synchronous generator, can be considered as a solution. The VSG can produce virtual inertia from energy storage during a short operation time, and the active power can be produced by a VSG similar to a synchronous generator. In this paper, an oscillation damping approach is developed for a DG using the VSG. The method is confirmed analytically, and verified through computer simulations. Finally, some laboratory experiments are conducted using 10-kW inverters and a transmission-line simulator.