Enhanced Power Quality in Grid-Connected Photovoltaic Systems Using a Novel Modular Multilevel Inverter Topology
نویسندگان
1 College of Applied Sciences, University of Fallujah, Fallujah, Iraq
2 Department of environmental science, Al Karkh University of Sciences KUS, Baghdad. Iraq
3 Department of environmental science, Al Karkh University of Sciences KUS, Baghdad. Iraq
doi
10.30501/jree.2025.534417.2496چکیده
Grid-connected photovoltaic (PV) systems face persistent power quality challenges, primarily due to the complexity of maintaining capacitor voltage balance in advanced multilevel inverters. This paper presents a fundamental redesign of the submodule architecture, the Hybrid Clamp-Bridge (HCB-SM), which eliminates this core issue through a deterministic passive voltage balancing mechanism, achieving superior power quality and efficiency without complex control, including elevated harmonic distortion and voltage imbalances under dynamic operating conditions. While Modular Multilevel Converters (MMCs) offer superior harmonic performance compared to traditional inverters, their implementation is hindered by complex capacitor voltage balancing requirements that increase control overhead and switching losses. This paper introduces a novel Hybrid Clamp-Bridge Modular Multilevel Inverter (HCB-MMI) topology with an integrated control strategy to fundamentally address these limitations. The core innovation lies in a unique submodule configuration that enables passive voltage balancing through deterministic current paths, eliminating 90% of conventional sorting computations. Combined with a modified nearest-level modulation scheme and resonant current control, the solution achieves unprecedented power quality and efficiency. Comprehensive MATLAB/Simulink simulations under diverse operational scenarios, including irradiance transients, nonlinear loads, and grid disturbances, demonstrate grid current THD below 3.5%, representing a 73–79% reduction compared to benchmarks, alongside 98.2% peak efficiency at partial loads, 2.3–3.4% higher than conventional MMCs. Capacitor voltage deviations remain under 1.5 V during fault conditions without active balancing intervention. The topology's simplified control architecture, with 5 μs latency, and self-regulating properties establish a new paradigm for high-fidelity solar integration, resolving the critical complexity-performance trade-off in multilevel converters.
