Direct Power Control of Grid Connected Voltage Source Inverters Using Port-controlled Hamiltonian System

Abstract

This paper presents a new direct active and reactive power control (DPC) scheme for a three-phase grid connected voltage source inverter (VSI) based on the passivity viewpoint using the port-controlled Hamiltonian (PCH) system. The proposed controller consists of feedforward and feedback parts. The feedforward part (the reference inputs) is generated through the flatness of the dynamics of the VSI model, which makes the error dynamics in the form of PCH system. The nonlinear feedback part is designed to enhance the damping of the error dynamics by using its Lyapunov function. The proposed control method has an ability of the finite time reaching condition similar to sliding mode control (SMC). Moreover, the exponential stability and uniform performance are guaranteed over all operating points without need for reaching a certain manifold. The proposed method is validated by using an experiment through hardware-in-the-loop system with a digital signal processor. The experimental results for the proposed method are compared with those using SMC-DPC method. The proposed method significantly reduces the total harmonic distortion in the output current without deteriorating the transient response of the active and reactive powers. In addition, it provides robust performance against the line impedance variations and the grid voltage sag.