Adaptive Interconnection and Damping Assignment Passivity-Based Control of Interlinking Converter in Hybrid AC/DC Grids

In this article, a nonlinear adaptive control strategy is proposed for a power conversion system (PCS) based on the interconnection and damping assignment passivity-based control. The PCS unit includes a dc/dc boost converter cascaded with a dc/ac inverter. The PCS system injects the predetermined values of active/reactive powers from a dc grid to the ac grid while the voltage of the interlinking capacitor is fixed. A disturbance observer is designed and implemented to estimate the output voltage of the dc grid as an unknown quantity. The proposed control strategy is derived based on the extended nonlinear model of the PCS in the synchronous reference frame. This model includes the dynamics of converters, interlinking capacitor, and the output filter of dc/ac inverter. The control commands are calculated through the assignment of desired damping and interconnection matrixes to the closed-loop system using a desired Hamiltonian energy function. The proposed strategy provides soft active/reactive power and voltage/current variations following the changes in the reference commands. The proposed control law is more feasible for experimental digital signal processing modules compared to nonlinear complicated control laws. Finally, the effectiveness of the proposed controller is tested using a set of time-domain simulations using realistic models for PCS components.