Robust mixed H2 / H∞ based optimal controller design for single-phase grid-connected converter

Abstract

In order to integrate more and more renewable energy resources to the main grid, single-phase grid-connected converters (GCCs) have gained more attention. However, the controller for a single-phase GCC is much more difficult to design than for a three-phase GCC. Traditionally, proportional plus integral (PI) or proportional plus resonant (PR) are widely used to control a single-phase GCC system. However, both the PI and PR controlled GCC show some drawbacks, such as slow response speed, poor robust performance against the systems' uncertainties and exogenous disturbance. In this paper, the detail state-space model of a single-phase GCC system is built, which includes the uncertainty and disturbance in the system to accurately reflect the practical system conditions. Then, robust mixed H2/H∞ optimal control technique is applied to design a full-state feedback controller for a single-phase grid-connected converter. The performance of proposed control method is evaluated by simulation. Simulation results demonstrate that the proposed control method has much more improved transient and steady state performance than PI controller.