DC bus voltage control for PV sources in a DC distribution system infrastructure

This paper proposes a design of a controlled voltage bus for a PV source to be used in a hybrid DC distribution system infrastructure. Load centers, boost converter, and distribution panels combine to link the solar collectors with multiple loads and Backup battery systems add to the complexity of a PV installation. The controlled voltage bus is constructed based on the design of a DC-DC boost converter. A Traditional DC-DC boost converter is limited to get a constant DC voltage as an input and boosting it to a certain voltage level as long as the load is fixed. The boost converter described in this paper is capable of receiving variable DC voltage as an input and give a constant boosted DC output voltage. The significant advantage of this device is that it is capable of producing a fixed voltage, with a very small ripple that can be neglected, while operating with variable load. The parameters of the DC-DC boost circuit were calculated such that it gives the device the ability of controlling a wide range of input voltage and be operated at a wide range of load variations. Closed-loop control of the boost converter utilizes a conventional proportional integral (PI) controller. Since the system has two variables which are the input voltage and the load, the duty ratio is not allowed to be constant to get a fixed output voltage. The PI controller is used in a closed loop system to obtain a suitable duty cycle to keep the output voltage constant according to the reference level of the DC-bus. Simulation and experimental results for different disturbance conditions show good performance of this proposed control system. The results verify the validity of the proposed model and show its practical use in renewable energy applications.