Processor in the loop test for algorithms designed to control power electronics converters used in grid‐connected photovoltaic system

摘要

Enhancement of photovoltaic (PV) system efficiency based on simple testing techniques is one of the most promising solutions. This is due to its low cost and easy implementation. This paper shows a way to develop applications based on a new method of operating the STM32F407-VG board. Thereafter, the processor in the loop (PIL) test can easily be conducted. This method requires an FT232RL USB-UART converter board as an external serial communication interface that can replace the frequently used internal STLink communication interface. The main advantage of this external device lies in the setting of its baud rate using the aliasing technique. This technique can provide an efficient solution to transfer data from the embedded board to the computer and vice versa at high baud rate. The PIL testing becomes faster and therefore more flexible. The studied case is a grid-connected small scale PV system. The produced power from the PV generator (PVG) is injected into the grid. The incremental conductance (INC) algorithm-based maximum power point tracking (MPPT) technique is developed for extracting the maximum power from the PVG. The dq current control method is presented for the three phase voltage source inverter (3-ph VSI). Further, a scenario of frequency changes in the grid is chosen in order to verify the phase-locked loop (PLL) ability to track the grid phase angle. The simulation results under MATLAB/Simulink show the efficiency of both controllers and dynamic behavior of the full PV chain. Next, the proposed PIL test is performed by automatically generating the C code from both control algorithms using the Simulink features. This C code is implemented on the STM32F407-VG board that acts as an external controller meanwhile the plant is still running on the host computer. The PIL test results show that the controllers simulated under MATLAB/Simulink behave in the same way once executed on the embedded board