Virtual inertia operation of renewables

The synchronous rotating inertia is the key parameter of power system stability. Increasing the penetration of nonsynchronous generators, e.g., wind turbine, photovoltaics, and energy storage system, in the power grids leads to some stability challenges due to the lack of rotating mass and kinetic inertia in the system. In this chapter, the effect of high penetration of renewables on power system stability is shown. Moreover, the recent low-inertia grid challenges in Europe and South Australia are presented. Technically, in order to achieve 100% renewables, providing virtual inertia is a demand. The virtual synchronous machine (VSM) is a promising solution to emulate the behavior of a synchronous machine and provide inertia virtually. In this chapter, the theoretical concept of VSM, as well as the control structure, is also presented. Furthermore, the VSM implementation in the power system is explained, and some RMS simulation results are provided in a fault situation. Since in a controller based on the swing equation, the current is not controlled in the short time frame directly, a current limitation controller is also implemented in VSM and scrutinized in this chapter.