S. K. Gudey, S. Andavarapu,
Volume 17, Issue 3 (September 2021)
Abstract
A three-phase dual-port T-type asymmetrical multilevel inverter (ASMLI) using two sources, solar forming the high voltage level and the battery forming the low voltage level, is considered for grid interconnection. A vertical shifted SPWM is used for the ASMLI circuit. A transformerless system for grid interconnection is achieved for a 100-kW power range. A well-designed boost converter and a Buck/Boost converter is used on the front side of the inverter. Design of battery charge controller and its controlling logic are done and its SOC is found to be efficient during charging and discharging conditions. A closed-loop control using PQ theory is implemented for obtaining power balance at 0.7 modulation index. The THD of the current harmonics in the system is observed to be 0.01% and voltage harmonics is 0.029% which are well within the permissible limits of IEEE-519 standard. The power balance is found to be good between the inverter, load, and the grid during load disconnection for a period of 0.15s. A comparison of THD’s, voltage, current stresses on the switches, and conduction losses is also presented for a single-phase system with respect to a two-level inverter which shows improved efficiency and low THD. Hence this system can be proposed for use in grid interconnection with renewable energy sources.
Sivaprasad Kollati, Satish Kumar Gudey,
Volume 21, Issue 4 (December 2025)
Abstract
To maximize the efficiency of solar energy conversion into electricity, photovoltaic (PV) system optimization is crucial. This is especially true for off-grid solar installations in remote areas lacking grid access. In order to maximize energy extraction from freestanding PV systems, regardless of fluctuating external conditions, this research provides a modified DC-DC converter and a novel Maximum Power Point Tracking (MPPT) technique. To ensure the photovoltaic (PV) system operates at full capacity despite rapid changes in weather conditions, the proposed solution utilizes the Modified Incremental Conductance MPPT algorithm that dynamically adjusts the system's operational parameters. Extensive simulations run in the MATLAB/Simulink platform confirm that the MPPT technique is efficient and effective. The proposed method outperforms traditional MPPT approaches in both convergence speed and output power stability. This research also develops a novel DC-DC converter to address the challenges given by the fluctuating solar irradiation. The modified DC-DC converter exhibits high gain and shorter settling time, and the improved MPPT method enhances the feasibility of deploying solar energy systems in off-grid and remote regions by enhancing the autonomy of standalone PV systems.
