Energy Function Based Modified Integrated Control Architecture for Grid Connected Inverter

Abstract

This paper presents an optimization-based integrated control architecture for grid-connected inverters. In this work, an adaptive control framework augments the conventional device level controllers of inverters for optimizing the inverter output based on grid dynamics. The individual controllers in the integrated architecture are prioritized based on a properly defined quadratic cost function that minimizes the state energy during grid dynamics. The proposed architecture overrides the issues in conventional inverter controllers since such designs are not capable of exhibiting superior performance over a wider range of grid dynamics, like a fault or sudden load change. The identification based proposed integrated control architecture ensures excellent ability to provide additional ancillary services, such as power smoothing and frequency regulation, even during variable operating point and parametric variations. The proposed framework was validated through simulation on a grid-connected inverter (GCI) and verified in real-time. The results show that optimization between controllers provides improved tracking during variable operating conditions and considerably reduces the harmonics when compared to each controller acting independently.