Abstract
The effect of continuous penetration of intermittent, distributed renewable energy generation has made it a necessity for the grid system to become more intelligent to enable the flow of electricity in a reliable and steady manner. This can be done by doing smart decisions such as replacing the outdated component of the conventional inverter with the newly and more effective components such as the Self-tuning adaptive controller. This research shows a control strategy by using an adaptive self-tuning controller in the conventional model. A controller based on Recursive Least Square Identification (RLSI) and pole shifting control was designed and implemented on the Grid Connected Inverter. For this to be achieved, all the PI controllers in the inner current control loop and outer voltage control loop were replaced and comparison between the two different controllers (Proportional Integral controller and Self-Tuning controller) was carried out. 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. Harmonic Analysis of the Grid-Injected Current and Grid Voltage was also studied. The grid voltage showed a 1.15% Total Harmonic Distortion (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 1.21% THD and 1.31% when using ST and PI controller respectively. The model was simulated on Matlab Simulink interface.

Key words: Self-tuning controller, RLS Algorithm, Pole shifting controller, STC