An Adaptive Multi-Resonant Current Controller for a Single-Phase Grid-Tied Converter With Grid Disturbance Rejection Capability

The grid-tied converters are always susceptible to abnormal grid disturbances, which are countered with the advanced current controllers. This paper presents an adaptive multi-resonant current controller (MRCC) in a current loop to maintain the converter synchronization with the grid under grid disturbance. The most critical disturbance like dc-offset, frequency variation, and harmonics in the grid voltage leads to current tracking performance degradation due to their non-adaptive nature. The modified second-order generalized integrator (MSOGI) based phase-locked loop (PLL) is proposed with grid frequency adaptability. The detailed analysis of the adaptive MRCC is presented with the dc-offset, frequency deviation, and harmonics in the grid voltage. The proposed MSOGI-PLL with an adaptive MRCC is tested under non-ideal grid conditions indicating the enhanced dynamic response over the non-adaptive methods. The efficacy of the frequency adaptive MRCC is tested on the laboratory prototype model of the single-phase GTC.