Oscillation Damping of a Distributed Generator Using a Virtual Synchronous Generator

Abstract

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.