Control for the Provision of Virtual Inertia by Wind Turbines with PMSG considering Wind Fluctuations

Wind turbines are able to contribute to the frequency stabilization of the electric grid by providing inertial power. As long as the grid frequency corresponds to the nominal value, a wind turbine in partial load range can be operated at the maximum power point (MPP) for maximizing the energy yield. In response to a frequency drop, an inertial control increases the power output for supporting the grid with a reduction of speed as a result. Once the frequency is stabilized, a return in the MPP by accelerating the drive train should happen. For this, the power output of the MPP tracking needs to be speed-dependent, which leads to power fluctuations when wind fluctuations are taken into account. A novel control structure is introduced that uses a special form of MPP tracking, targeting a smooth power output and a guarantee of operational stability. Its behavior is analyzed on the basis of simulation results.