The Implementation of Effective Modulation Schemes to Improve the Power and Harmonic Losses in Grid-Tied Solar NPC Inverter

Abstract

The growing energy demand, rising fossil fuel prices, and exceeding greenhouse gas emissions require large-scale integration of clean and renewable energy resources. Solar Photovoltaic (PV) system is the potential prospective energy resource to overcome the challenges of conventional grid. Effective power conversion topologies are the prominent need of the PV system to optimize the power and harmonic contents. Three level neutral point clamped (NPC) inverter comparatively produces less harmonics and increases the power delivery compared to the conventional and two-level inverters. Therefore, this research presents the deployment of three level NPC inverter to optimize the switching and power losses in grid connected 250 kW solar PV array. Moreover, power generation, current and voltage characteristics, and fast Fourier transform analysis is performed in MATLAB / Simulink directory with the help of Simpowersystem and Simelectronics toolboxes. To optimize the switching and power losses, sinusoidal PWM and space vector PWM are used to control the duty cycle of IGBT power switches in the proposed NPC inverter. The grid side 3 phase AC output voltage of the proposed inverter is connected to 15 kV grid with the help of 3 phase step up transformer. For 3 phase grid-tied system, the performance evaluation section of the proposed research shows the effectiveness of space vector PWM over sinusoidal PWM.