DC-link Voltage Control Using Battery-side Controller in a Hybrid System

Abstract

This work aims to model the PV-Battery hybrid system as well as design a controller used to stabilize the voltage at the DC-link for the load. It is intended to make the voltage between the battery and PV system stable, or it can be said that the voltage at the load becomes stable. The input system used is battery current and PV current is considered as a disturbance because of its characteristics that cannot be controlled when generating maximum power. Therefore, a full order state feedback controller with integrator is designed to reduce the steady state error. In addition, an algorithm is needed to estimate the PV current and at the same time reduce sensor utilization. This work utilizes Disturbance Observer to estimate these parameters as well as disturbance rejection. To verify the proposed system, there are three scenarios. The first scenario tests the system with constant PV load and current. The second scenario tests the system with varying PV current, and finally tests the system with varying load and current. From the scenarios, the system performed well with output voltage RMSE values equal to 0.003 in the first scenario, 0.4 in the second scenario, and 0.481 in the third scenario.