Optimization of Inverter Control Algorithm of Single-Stage Photovoltaic System under Low Voltage Grid Conditions Using Fuzzy PI Controller

Nowadays, the use of renewable energy has become very important. Considering the changes in radiation intensity and the continuous switching of the inverter, the control algorithm of the inverter plays an important role. In the DC part, adjusting the voltage of the DC link is very important, and stabilizing the voltage at this point will have a significant impact on the performance of the entire system. In the existing methods in order to regulate the voltage, a proportional integral controller (PI) is used and the coefficients of this controller are usually fixed and its performance decreases when the working conditions change, so using structures with an approach Fuzzy is noticeable. The use of the fuzzy PI controller improves the performance of the controller, increases the speed of realizing the maximum power tracking algorithm, reduce the fluctuations of the DC link voltage and the output power of the photovoltaic system inverter. In this article, a new structure based on the fuzzy PI controller is presented in order to improve the performance of the inverter control algorithm, so that the DC link voltage becomes equal to the reference value for 2 seconds faster than the normal PI method and the grid voltage range for 1/5 seconds faster. And the active power of the grid will reach a steady state 2 seconds faster and the fluctuation of these variables will be significantly reduced.