Advanced control of inverter-interfaced generation behaving as a virtual synchronous generator

The amount of inverter-interfaced distributed generation in the electrical networks is continuously increasing. However, the presence of a large amount of local generation is raising a number of issues referring to the power system stability. In particular, high sensitivity in the response to frequency variations after disturbances is emerging, because of the low inertia of the local generators. Recent studies indicate the possibility of introducing some forms of short-term energy storage and operating on the control of the inverter to introduce a virtual inertia in the system, emulating the typical behavior of synchronous generators. This paper starts from the concept of virtual synchronous generator introduced in the literature and presents an extended model of the control system for a voltage source inverter embedding the typical functions of a synchronous generator, including virtual inertia, active and reactive power capability limits, and appropriate protections to enable fault ride-through capability. Simulations are presented by using the data of a real inverter in order to show the effectiveness of the proposed controls and the effects of introducing a dynamically variable virtual inertia.