Dual Loop based Andronov-Hopf Oscillator Control of Grid-Connected Photovoltaic Systems

The grid-connected dc-ac converters encounter significant challenges in maintaining stable operation on both dc and ac sides, especially with solar photovoltaic (PV) at the dc-link. The grid-forming (GFM) converter is nowadays preferred due to its capability to establish and maintain grid stability and synchronization, even under weak grid conditions. This paper describes a dual-loop control structure that cascades Andronov-Hopf oscillator (AHO)-based virtual oscillator (VO) control with dual voltage and current control to directly address voltage variations and control the converter output variables. Additionally, the power synchronization loop of VO control incorporates dc-link dynamics to facilitate maximum power point tracking (MPPT)-based PV systems. The simulation results show that the proposed controller enables PV to dispatch power at MPPT while providing stable synchronization at the ac side. The performance of the controller is further examined by adjusting the internal VO parameter for current gain and the external grid’s R/X ratios.