Control of a flexible platform for photovoltaic grid-connected systems using a DSP-microcontroller arrangement

In this paper, a flexible platform for the connection of Solar Photovoltaic Panels to the utility grid is developed. The platform is made with the Power Subsystem, which includes a DC/DC boost converter and a 3-phase DC/AC converter as the main devices, together with the Control Subsystem, which includes a DSP-microcontroller arrangement made by a floating-point DSP and a fixed-point microcontroller. A detailed mathematical model of the plant is described for analysis purposes and the real-time control algorithms for the DC/DC and DC/AC converters are established. Both processors are intended to do real-time control in an easy way, and the communication process between them is carried out with the McBSP bus in a MASTER/SLAVE configuration. The flowcharts of the main programs in both processors are shown together with the detail explanation of the interrupt capabilities employed: the DC/DC boost converter is controlled by selecting the adequate duty cycle in real time, whereas the DC/AC converter is managed by a d-q control approach where the decoupled regulation of the instantaneous active and reactive powers fed to the 3-phase utility grid is achieved, allowing unitary power factor operation. Several measurements of the involved variables of the platform are shown in order to evaluate the performance of the exerted control algorithms. The possibility of exerting future complex algorithms and high computational tasks are also validated. © 2011 Praise Worthy Prize S.r.l. - All rights reserved.