Modeling and implementation of a self-tuning adaptive controller of an inverter in agrid-connected microgrid

Abstract

The grid system has become more intelligent to enable the flow of electricity in a reliable and steady manner due to the consequences of unceasing penetration of distributed renewable energy generation. This can be done by doing smart decisions such as replacing the outdated component of the conventional inverter with the more effective and recently developing components such as the Self-tuning adaptive controller. This paper presents a control strategy by incorporating an adaptive self-tuning controller into the conventional model. The controller developed is based on Recursive Least Square Algorithm (RLSA) with variable pole shifting control and was then implemented on the Grid Connected Inverter. The conventional PI controller in the inner current control loop and outer voltage control loop of the conventional model were replaced and comparison between the two different controllers (Proportional Integral controller and Self-Tuning controller) was carried out. The model was simulated on MATLAB Simulink interface. Performance analysis of inverter controller and change in grid filter inductance were studied and all the result showed that ST controller have a better system response and a better performance than when PI controller is used. The grid voltage showed a 1.15% THD when using ST controller and 1.36% THD when using PI controller which resulted to 18.26% reduction in THD. The injected current shows a 1.31% THD and 1.21% when using PI and ST controller respectively.