Power quality and stability assessment of hybrid microgrid and electric vehicle through a novel transformation technique

In this study, a novel transformation technique based on combined AC and DC grid-based hybrid microgrid and electric vehicle operation is proposed to offer better power quality and power reliability operation. To produce constant wind speed, a novel wind speed generation method is proposed by using a 10 kW rating-based constant ventilation fan. Due to the suggested AC-DC hybrid microgrid approach, the conversion device requirement is reduced during the direct integration of EV and the battery energy storage device. In addition to that, an adequate centralized energy management control structure is proposed by combining wind power control, battery storage, and EV power control, and coordinated inverter control respectively, to offer excellent parallel action of numerous wind plants and inverters without needing extra voltage and frequency controller. Further, to reduce the computational burden, a novel transformation having the capability to handle both three-phase unbalanced voltage and current components is applied through a vector representation in a novel d'q' revolving frame. The MATLAB/Simulink-based developed system undergoes different test system conditions as a failure of one inverter and sudden addition of wind plant during varying EV conditions and varying nonlinear/unbalanced load demand at the shutdown conditions of wind power generation. From the simulated results, it is found that with the presence of 19.96% non-linear load, the improvement percentage of utility, top, and bottom inverter is 97-98%, 96-97%, and 99% respectively. In addition to that, the proposed transformation-based grid current results are compared with the traditional instantaneous power theory-based grid current results and found that significant harmonic percentage improvement results are achieved with the presence of the same non-linear load condition. Further, the proposed method takes minimum time i.e., only two to three cycles to settle the power fluctuation during transient conditions. As the above limits are well within the IEEE-1541 and IEEE 1547-2018 and offer faster settling time, then it can be suggested for real-microgrid test systems to achieve better power quality and reliability.

Automated summary

This study proposes a novel transformation technique based on combined AC and DC grid-based hybrid microgrid and electric vehicle operation to enhance power quality and reliability. A new method for generating constant wind speed is introduced using a constant ventilation fan with a 10 kW rating. The suggested AC-DC hybrid microgrid approach reduces the need for conversion devices when integrating electric vehicles and battery energy storage devices directly. A centralized energy management control structure is proposed, incorporating wind power control, battery storage, EV power control, and coordinated inverter control, to enable excellent parallel action of multiple wind plants and inverters without requiring additional voltage and frequency controllers. A novel transformation method is applied to handle three-phase unbalanced voltage and current components, reducing computational burden. Simulation results demonstrate significant improvement in utility, top, and bottom inverter performance under different system conditions, as well as faster settling time. This proposed approach can be applied to real microgrid test systems to achieve better power quality and reliability.