A low cost, light weight and accurate photovoltaic emulator

This paper proposes a cost effective, compact and precise photovoltaic emulator. It is able to emulate accurately the current-voltage characteristics of a PV source for varying temperature and solar radiation. The proposed system also has the ability to emulate the re-configuration of the PV panels for series and parallel connection. The emulator is developed with a galvanically isolated power electronic topology with high frequency transformer, to achieve a light weight and compact system for easy handling. The proposed system has features of online set point variation of insolation and temperature. Standard module of V_oc=21 volts and I_sc=2 Amp at 1000 w/m² is chosen as a base selection and panels with desired configuration can be formed by appropriate selection of the series and parallel bits provided on the front of unit for the purpose. The unit can provide up to 150 W of power. Detailed design is provided for the flyback converter used as the basic power electronic topology at the heart of the emulator. The control of the output voltage and current is achieved using a types-3 compensator, designed using K factor approach to achieve good dynamic response. The controller and the monitoring panel are implemented using a `low end´ dsPIC microcontroller. All the hardware details of the developed prototype are presented. Experimental results are shown for several cases of panels connected in series and/or parallel for different radiation levels. It is observed that the weight of this 150 W unit is about 1 kg, including casing and auxiliary components.