| Abstract |
This paper presents a systematic methodology for design and tuning of the controller of LCL grid-connected converters. The proposed approach is derived from the impedance/admittance stability formulation, which eases the controller modelling of LCL grid-connected systems. After system modelling, a modified sensitivity function is defined to analyze the closed loop dynamics. For practical development, the control objectives are linked to main requirements in wind turbine applications: 1) the current control time constant should be minimized and 2) active damping actions should effectively mitigate the LCL resonance. After the theoretical development, an insightful case study is provided. It is shown that the tuning problem can be solved approximately by root-loci inspection and an optimum solution can be found by direct search. The theoretical approach is experimentally verified by a lab-scale prototype that uses the same parameters of the case study. |
