PIL Test for Voltage Source Inverter control used in Off-grid PV system

摘要

This paper treats the case of the off-grid photovoltaic (PV) system, feeding a three-phase resistive load and working only during sunlight availability. In this case, backup batteries are not used. So, no charge controller is needed, neither any DC-DC power converter as long as the PV generator (PVG) delivers a voltage greater to a certain value that keeps good functionality of the inverter. Thus, this PV chain is reduced only to PV array and three-phase voltage source inverter (3-ph-VSI), followed by (delta/wye) transformer. The discrete virtual Phase Locked Loop (PLL) is used to generate a fixed frequency (50 Hz). The proposed system topology allows designing a low cost system, and providing necessary power that can meet the daytime load demand. Next, Processor in the Loop (PIL) method is performed in order to test the hardware implementation of the inverter control algorithm already simulated with MATLAB/ Simulink. This is done by creating the PIL block which will be run in the STM32F407-VG discovery board, while the plant model will be simulated in the host computer. The ST-LINK communication interface is used to connect the host computer to the embedded board.