Virtual synchronous generators classification and common trends

With the increasing penetration of photovoltaic systems, conventional plants, which are based on synchronous machines, will be displaced. Inverter based photovoltaic systems behavior is quite different from traditional generators in both electrical and mechanical dynamics, and grid stability can be negatively affected. A solution towards stability improvement is the use of virtual synchronous generator (VSG) control techniques, which are based on emulating the response of conventional generators in the inverter. In this paper, the principal VSG trends are reviewed by classifying them according to the characteristics of the synchronous generator that are replicated, and their main benefits and drawbacks are studied. The flexibility of the inverters allows adding special characteristics to the VSG in order improve the traditional generators response and some functionalities have been proposed. Proposed special characteristics will also be analyzed.