Virtual inertia control for transient active power support from DFIG based wind electric system

This paper presents the design and development of Virtual Inertia control in a DFIG based wind energy system for transient active power support to grid. Inertia required for the active power support is calculated from fundamental equations and are used as design values for the generator/turbine. The rotor is connected to a dc bus through a bi-directional ac-dc converter and on the ac side the frequency and voltage is varied as directed by a Virtual inertia controller. With the shaft speed and grid frequency as inputs the controller gives out the rotor injection frequency and voltage. The active power sharing across rotor and stator is facilitated by controlling the phase angle of the inverter pole voltage with respect to the rotor voltage. The entire system is executed in MATLAB/Simulink Model and its performance is evaluated under various wind speed conditions. At different wind speeds the inertial response and the statorrotor power sharing are presented for varying inverter phase angles. The power balance is verified in each case to validate the effectiveness of the proposed virtual inertial controller.