Overview of Virtual Synchronous Generators: Existing Projects, Challenges, and Future Trends

Abstract

The rapid growth in renewable energy-based distributed generation has raised serious concerns about the grid’s stability. Due to the intrinsic rotor inertia and damping feature and the voltage (reactive power) control ability, traditional bulk power plants, which are dominated by synchronous generators (SG), can readily sustain system instability. However, converter-based renewable energy sources possess unique properties, such as stochastic real and reactive power output response, low output impedance, and little or no inertia and damping properties, leading to frequency and voltage disturbance in the grid. To overcome these issues, the concept of virtual synchronous generators (VSG) is introduced, which aims to replicate some of the characteristics of the traditional synchronous generators using a converter control technique to supply more inertia virtually. This paper reviews the fundamentals, different topologies, and a detailed VSG structure. Moreover, a VSG-based frequency control scheme is emphasized, and the paper focuses on the different topologies of VSGs in the microgrid frequency regulation task. Then, the characteristics of the control systems and applications of the virtual synchronous generators are described. Finally, the relevant critical issues and technical research challenges are presented, and future trends related to this subject are highlighted.

Inertia Identification and Analysis for High-Power-Electronic-Penetrated Power System Based on Measurement Data

“…From Equation (7), it can be seen that the inertia released by the SG after a large disturbance is not only determined by the inertia coefficient and rated capacity of the SG but also affected by the actual frequency deviation.…”

“…To deal with the challenge of frequency instability caused by the integration of "zeroinertia" power sources, control techniques such as droop control, virtual inertia (VI) control, and virtual synchronous generator (VSG) control have been proposed [6,7]. Electronic converters can be controlled in two modes, known as the grid-forming mode and the grid-following mode [8,9].…”

“…The grid-following control converter operates in the form of current sources, and its output is controlled by the outer loop current reference. The grid-following source can provide frequency support to the system if frequency regulation control instructions are added [7]. Unlike the widely accepted and applied grid-following control, grid-forming control, particularly VSG control, has gained more attention in recent years and is still under discussion [10].…”

The Development of Renewable Energy in Mineral Resource Clusters—The Case of the Siberian Federal District

“…A similar purpose is served by virtual synchronous generators-inverters that provide "synthetic inertia" to increase grid stability for renewable-energy-based distributed generation [60]. Virtual synchronous generators have proven effectiveness for microgrids [61]; however, for large grids (which in the future will connect all renewable energy facilities with consumers), low inertia is more challenging [62].…”

Suppression Strategy of Subsynchronous Oscillation Based on Dynamic Voltage Compensation Control for Grid-Forming D-PMSG in Weak Grid

“…Under the background of continuous growth of global wind power installed capacity, to make up for the lack of system inertia caused by the introduction of high proportion power electronic equipment, the grid-forming VSG control technology is applied to the grid-side converter of D-PMSG, which provides inertia support to the power system by mimicking the transient characteristics of synchronous generator [1][2][3]. Under the condition of high proportion power electronic equipment, the interaction between D-PMSG and the weak grid is prone to subsynchronous oscillation, which is particularly prominent in remote areas [4,5].…”