Instantaneous Symmetrical Component based Virtual Oscillator Control
Ritwik Ghosh, Narsa Reddy Tummuru, Bharat Singh Rajpurohit · 2022
Virtual Oscillator (VO) control is a timedomain control strategy for grid-supporting and gridforming inverters.Existing VO Controllers (VOC) use single two-dimensional non-linear limit cycle oscillators to produce the α and β components of control voltages.The α and β components of output currents of the inverter are used as feedback to the controller.Zero component entities are neglected both in the feedback and output of the controller.Control over the α and β axis is not decoupled.This paper has introduced instantaneous symmetrical component based VOC to improve the properties of VOCs, stated earlier.The proposed VOC uses three Andronov-Hopf oscillators to generate the positive, negative, and zero sequence components of the control voltages.The outputs of the oscillators are modified as required by each sequence.The performance of the proposed VOC is verified in two conditions, which are not reported in the earlier literature of VOCs.The first condition is grid-supporting operation in presence of unbalanced grid voltages.The second condition is grid-forming operation when single-phase and threephase inverters are integrated into the same islanded system.The proposed VOC can be configured to provide either (𝝎-P, V-Q) or (V-P, 𝝎-Q) droop.This paper has presented (𝝎-P, V-Q) droop.