PROJECT TITLE :

A Root-Locus Design Methodology Derived from the Impedance/Admittance Stability Formulation and Its Application for LCL Grid-Connected Converters in Wind Turbines - 2017

ABSTRACT:

This paper presents a systematic methodology for the look and therefore the tuning of this controller in LCL grid-connected converters for wind turbine applications. The planning target is formulated as a minimization of this loop dominant time constant, that is in accordance with standard style guidelines for wind turbine controllers (quick time response and high stability margins). The proposed approach comes from the impedance/admittance stability formulation, that, on one hand, has been proved to be suitable for the controller design when the active damping is implemented and, on the other hand, has additionally been proved to be very suitable for system-level studies in applications with a high penetration of renewable energy resources. The tuning methodology is as follows: first, the physical system is modeled in terms of the converter admittance and its equivalent grid impedance; then, a sensitivity transfer perform comes, from that the closed-loop eigenvalues can be calculated; finally, the set of control gains that minimize the dominant time constant are obtained by direct search optimization. A case study that models the target system in an exceedingly low-power scale is provided, and experimental verification validates the theoretical analysis. A lot of specifically, it's been found that the answer that solves the minimization of the current controller time constant (wind turbine controller target) additionally corresponds to a highly damped electrical response (robustness provided by the active damping).