摘要：LCL-type grid-connected inverters are crucial for the integration of distributed energy resources
in power grids. In order to achieve high quality of the grid current for a compliance with IEEE
and IEC standards and maintain system stability, not only an LCL resonance damping method
but also a proper controller design is required. This paper proposes a systematic and
generalized design approach for PR controllers to stabilize the operation of single-phase LCLtype
grid-connected inverters under different conditions of grid voltage. The designed PR
controller contains multiple resonant components to effectively eliminate high-order current
harmonics and deal with the variation of grid frequency. Phase margin is taken into account
when designing the PR controller to guarantee system stability. The efficacy of the proposed
method is verified by both simulation and real-time hardware-in-the-loop experiments using a
Typhon HIL 402 system. The results show that the designed PR current controller is capable of
significantly reducing grid-current harmonics when the system operates with distorted grid
voltage. In addition, between grid-current and inverter-current feedback approaches, the former
results in a grid current with a higher quality.
