Decoupling Control Scheme for VSG-WPPs to Participate in Grid Frequency Response

By adopting the virtual synchronous generator (VSG) scheme with the inertia emulation controller and droop controller, wind power plants (WPPs) can participate in inertial response (IR) and primary frequency regulation (PFR). According to the analysis in this article, besides the well-known dynamic coupling between the wind turbine operating point (WTOP) controller and the inertia emulation controller, there is a static coupling between the WTOP controller and the droop controller. These couplings would impair the IR and PFR characteristics of the VSG controlled WPPs (VSG-WPPs). The equivalent droop coefficient of the VSG-WPPs is no longer equal to the setting value and changes under different operation conditions. To eliminate these adverse impacts, a decoupling control scheme is proposed. According to the MATLAB simulations and real-time hardware-in-loop testing results provided in this article, under the same power disturbance, the frequency response characteristics of the WPPs with the proposed scheme are much better than the WPPs with the original scheme.