### Literature Review
The Internet of Things (IoT)-based power management unit to identify the PQ issues and the implementation of an ANN-based controller was designed for SHAPF to reduce THD [22]. The modern AC-DC microgrid with the intelligent FL-PI and FL-PID controller was designed with the view of minimizing PQ issues and improving voltage stability. In addition, performance analysis was carried out with two different case studies with dynamic load changes [23]. An adaptive full order observer-based control algorithm was developed for the UPQC to improve the PQ due to its fast response in fault detection for all positive sequence components, and high accuracy in monitoring under all various loads/grid conditions. In addition, a BBO algorithm was employed for the optimal tuning of Kp and Ki values for PIC on UPQC to minimize the DC-Link voltage oscillations [24]. However, the PQ issues for the micro-grid integrated distribution network were addressed using UPQC to mitigate voltage imbalances and current harmonics. An adaptive network-based fuzzy inference system was proposed to maximize the utilization and efficiency of the system [25]. An automated shifting method between the grid and island modes was developed for PV battery integrated UPQC in the view of addressing the PQ issues with low disturbance to the local loads. Further, the system performance was validated with experimental results [26]. The combination of both the improved bat algorithm and moth flame algorithm optimization-based hybrid control technique was developed to address the PQ issues in the micro-grid system in the view of minimizing the error function of power variation. In addition, the operation cost of renewable sources was reduced with the optimal tuning of Kp and Ki parameters [27]. An ANN controller based on a hybrid combination of reactive power control with unit vector template generation was designed for UPQC to mitigate PQ issues effectively. In addition, solar PV is connected to reduce the ratings of the power converters, and stabilize the DC-Link capacitor voltage during faulty and load variation conditions [28]. In addition, the novel sequence-component detection method hybridized with unit vector-template generation was proposed for the double-stage solar integrated UPQC to diminish PQ issues [29]. The review of various topologies, compensation techniques, controllers, and technological advancements in recent years for the UPQC were outlined with the motive of eliminating PQ issues [30]. Furthermore, the novel synchro-squeezing wavelet transform and ANN-based hybrid control algorithm were developed for the shunt controller of distributed generation integrated UPQC to detect and identify and control the PQ events regularly. In addition, a comparison was carried out with the ANN controller [31]. The optimal gain coefficients of modified active-power filter (MAPF) with a power filter compensator-kit (PFCK) were suggested with Harris hawk optimization (HHO), grasshopper optimization algorithm (GOA), artificial bee colony (ABC), and differential evolution (DE) to minimize current and voltage harmonics in addition to the diminishing the controller error [32]. The grid-connected network with an adaptive FL-C based on a series active power filter was designed to address PQ problems such as voltage fluctuations/interruptions, reduction of current harmonics, and maintaining constant DC-Link voltage [33].