Enhanced orthogonal signal generator for a single-phase grid-connected converter

This study presents a new orthogonal signal generation (OSG) technique for the control system of a single-phase grid-connected voltage-source converter (VSC). The existing methods mostly suffer from delay, rely on the system parameters, or require multiple inputs. Among them, the second-order generalised integrator (SOGI) excludes the drawbacks of the other methods and shows better steady-state and dynamic response. The proposed OSG method here includes the advantages of the SOGI technique while demonstrating superior dynamic response and higher disturbance rejection capability. It is structurally simple without adding complexity to the control system. The proposed method is implemented in a DQ-frame current controller and its feasibility and reliability are verified through mathematical analysis, simulation, and experimental results.