Application of Whale Optimization Algorithm Based FOPI Controllers for STATCOM and UPQC to Mitigate Harmonics and Voltage Instability in Modern Distribution Power Grids

In recent modern power systems, the number of renewable energy systems (RESs) and nonlinear loads have become more prevalent. When these systems are connected to the electricity grid, they may face new difficulties and issues such as harmonics and non-standard voltage. The proposed study suggests the application of a whale optimization algorithm (WOA) based on a fractional-order proportional-integral controller (FOPIC) for unified power quality conditioner (UPQC) and STATCOM tools. These operate best with the help of their improved control system, to increase the system's reliability and fast dynamic response, and to decrease the total harmonic distortion (THD) for enhancing the power quality (PQ). In this article, three different configurations are studied and assessed, namely: (C-1) WOA-based FOPIC for UPQC, (C-2) WOA-based FOPIC for STATCOM, and (C-3) system without FACTS, i.e., base case, to mitigate the mentioned drawbacks. C-3 is also considered as a base case to highlight the main benefits of C-1 and C-2 in improving the PQ by reducing the %THD of the voltage and current system and improving the systems' voltage waveforms. With C-2, voltage fluctuation is decreased by 98%, but it nearly disappears in C-1 during normal conditions. Additionally, during the fault period, voltage distortion is reduced by 95% and 100% with C-2 and C-1, respectively. Furthermore, when comparing C-1 to C-2 and C-3 under regular conditions, the percentage reduction in THD is remarkable. In addition, C-1 eliminates the need for voltage sag, and harmonic and current harmonic detectors, and it helps to streamline the control approach and boost control precision. The modeling and simulation of the prepared system are performed by MATLAB/Simulink. Finally, it can be concluded that the acquired results are very interesting and helpful in the recovery to the steady state of wind systems and nonlinear loads, thereby increasing their grid connection capabilities.