An Implementation of Hybrid Control Strategy for Distributed Generation System Interface Using Xilinx System Generator

This paper presents an analytical study and hardware-in-loop (HIL) cosimulation design of a grid-connected inverter system with a combinational robust observer-based modified repetitive current controller. In this study, main attention is paid to improve power quality and tracking performance of a distributed generation (DG) interfacing system under various perturbations. The inherent delay in convergence of conventional repetitive controller (RC) is reduced by introducing a low pass filter in delay line and this configuration is named as modified RC (MRC). By adding an observer with MRC, system states can be reconstructed, which improve the system dynamic response. Robust stability and convergence criterion are derived in terms of linear matrix inequality using combined Lyapunov function and singular value decomposition technique, which determine the suitable parameters of feedback control and state observer gains. By utilizing these gains, the switching signals are generated to operate the DG interfacing inverter effectively. The performance of proposed controller is compared with traditional proportional integral, proportional resonant, and MRC under both normal and fault conditions. Finally, HIL cosimulation is performed by realizing the power circuit in MATLAB/Simulink as a simulation model and a control structure using Xilinx system generator platform as burnt in hardware Virtex-6 field programmable gate array (FPGA) ML605 evaluation kit.