A Survey on Grid Coupled Power Conversion Devices That Implement Virtual Inertia

The introduction of renewable energy sources (RES) into the electrical grid has brought about challenges to maintaining reliability. RES is mostly derived from solar and wind resources that do not have the ability to support the electrical grid frequency. Traditional synchronous generators (SG) such as steam-driven turbines utilize the inertia created by the rotations of the systems rotor to maintain frequency during frequency deviations in the electrical grid. RES does not have rotating inertia to buffer changes in frequency and is not able to assist in the maintenance of grid frequency within desired ranges. The concept of virtual inertia has been introduced to describe technology that allows RES to respond to grid frequency events in a manner equivalent to the SG. The use of power electronics to connect RES power systems to the grid will eventually replace many SGs. Power converters known as virtual synchronous machines (VSM) are being implemented to provide virtual inertia on the grid. This paper presents different power electronic devices and control methods that provide the ability of renewable power systems to participate in grid frequency regulation.