Control Strategies Of Three-Phase Distributedgeneration Inverters For Grid Unbalanced Voltage Compensation

Abstract

This paper presents a new nonlinear current control strategy based on back stepping control and high-order sliding mode differentiator in order to employ distributed generation (DG) unit interfacing converters to actively compensate harmonics/ inter harmonics of local loads. The converter-based DG unit is connected to a weak grid (with uncertain impedance) and local load through an LCL filter.

The proposed strategy robustly regulates the inverter output currents and delivers pure sinusoidal, three-phase balanced currents to the grid. The new controller demonstrates the robust performance and robust stability of the DG unit system with respect to the filter parameters uncertainties, grid impedance, grid frequency, and grid voltage as well as the unknown load dynamics that include unbalanced loads and nonlinear loads with harmonic and inter harmonic currents.