A static synchronous compensator (STATCOM) is a powerful mechanism for balancing reactive power and uplift voltage stability in a transmission system. Nowadays, the desire to save energy by reducing losses is prioritized as an essential target instead of increasing the power generation for the sustainability of any nation’s growth plans. As a result, power-electronics-based converters are more significant for power savings in transmission systems. STATCOM based on voltage source converters (VSC) are operated to improve on stable performance conditions as well as to minimize the harmonic distortions in a power system. Hence, this paper explores low harmonic distortions of fifteen-level VSC structured STACOM using only one DC-link voltage to balance the reactive power and to manage the voltage profile in large power transmission systems. STATCOM consisting of H-bridge type VSCs and binary weighted transformers was utilized to maintain an AC system voltage at 132 kV, 50 Hz. The three stages of VSCs were operated with meticulous firing angles based on converter levels for controlling THD (total harmonic distortion) and providing system improvement. The proposed model of the fifteen-level H-bridge type voltage source converters with fuzzy logic decoupled control algorithm based STATCOM can be used for large power range applications with a small number of switches. This model attained stable operation of the system with a low harmonic deviation at any dynamical conditions. The simulation results using MATLAB showed that the system’s operation was enhanced, with a smoother response and improved steady state performance.

Conventional boost-based Grid-Connected Photovoltaic (GCPV) systems suffer from high input current ripple, voltage stress, limited gain at high duty ratios, and poor dynamic performance during Low-Voltage Ride-Through (LVRT) events. Furthermore, multi-input configurations relying on individual boost stages increase physical size and system complexity. To address these limits, this paper presents a 117 kW two-stage Dual-Input Single-Output Grid-Connected High-Gain Converter Photovoltaic (GCHGCPV) system. Standard PI loops manage the grid and battery, while an algebraic adaptive duty ratio law engages strictly during grid faults to eliminate PV integral delay. MATLAB/Simulink simulations under variable irradiance (200 to 1000 W/m²) and symmetrical grid sags, the P&O algorithm achieves a 98.6% average tracking efficiency, while the adaptive control suppresses transient peak DC-link overvoltage to 0.177% - 1.064% (reaching a maximum of 656.9 V). This maintains 193.1 V of safety headroom below the 850 V trip threshold. Moreover, grid current Total Harmonic Distortion (THD) remains strictly within IEEE standards across all conditions.