Smart Motor Drive Providing Inertia Support for the Grid by Applying Virtual Synchronous Generator Control

The increasing penetration rate of inverter-interfaced distributed generators (DGs) will lead to the inertia decrease of the grid. To solve it, virtual synchronous generator (VSG) control, which enables inverter-interfaced DGs to have inertia like synchronous generators (SGs), has been proposed. However, VSG control requires extra energy storage to emulate kinetic energy fluctuation in rotating mass of SGs. In this study, kinetic energy of motors existing in the grid as loads is temporarily utilized to absorb disturbance in the grid so that the cost of energy storage is minimized. Furthermore, as a large portion of loads in the grid consists of motors, large inertia support can be expected. To achieve it, VSG control is applied to grid side converter of back-to-back ac-dc-ac converter in a motor drive system, and coordinated control between VSG control and motor speed control is proposed. The effectiveness of suppression of grid frequency fluctuation by the proposed control system is shown through simulation results.