Electric Vehicles (EVs) are projected to be one of the major contributors to energy transition in global transportation due to their rapid expansion. High-level of EVs integration into the electricity grid will introduce many challenges for the power grid planning, operation, stability, standards, and safety. Therefore, the wide-scale adoption of EVs imposes research and development of charging systems and EV supply equipment (EVSE) to achieve expected charging solutions for EV batteries as well as to improve ancillary services. Analysis of the status of EV charging technologies is important to accelerate EV adoption with advanced control strategies to discover a remedial solution for negative impacts and to enhance desired charging efficiency and grid support. This paper presents a comprehensive review of EV charging technologies, international standards, the architecture of EV charging stations, and the power converter configurations of EV charging systems. The charging systems require a dedicated converter topology, a control strategy, compatibility with standards, and grid codes for charging and discharging to ensure optimum operation and enhance grid support. An overview of different charging systems in terms of onboard and off-board chargers, AC-DC and DC-DC converter configuration, and AC and DC-based charging station architectures are evaluated. In addition, recent charging systems which are integrated with renewable energy sources are presented to identify the power train of modern charging stations. Finally, future trends and challenges in EV charging and grid integration issues are summarized as the future direction of the research.

Grid integration of solar photovoltaic (PV) systems has been escalating in recent years, with two main motivations: reducing greenhouse gas (GHG) emission and minimizing energy cost. However, the intermittent nature of solar PV generated power can significantly affect the grid voltage stability. Therefore, intermittent solar PV power generation and uncertainties associated with load demand are required to be accounted for to gain a holistic understanding on power grid voltage stability with the high penetration of PV energy sources. This article presents a framework for power grid voltage stability analysis considering uncertainties associated with PV power generation and load demand using Monte Carlo simulation. Commonly used voltage stability indicators such as critical eigenvalue, line loss, reactive power margin have been considered in the proposed framework. The proposed methodology has been verified by analyzing the voltage stability of the IEEE 14 bus test system, with the high penetration of PV energy sources and considering uncertainties associated with load demand. The results provide a clear insight into the voltage stability of power grid with different penetration levels of PV energy sources into the power grid.

Microgrids gain popularity due to their economical and environmental benefits along with less power losses and smaller infrastructure. But it has a number of fundamental governance and operational challenges such as power quality, power system instability, reliability, and protection issues. Microgrid protection strategy is a prime issue for reliable operation of microgrid in the real world. The strategy must meet the essential conditions in AC and DC microgrid protections both in grid-connected and islanded operational modes. Different protection schemes have been developed as published in several different research articles but they are not suitable or efficient for both modes of operation due to operational challenges in microgrid protection. This paper presents a comprehensive review and comparative analysis of protection schemes and their implementation challenges for different microgrid architectures with various operational requirements. The challenges associated with the implementation of microgrid protection schemes are identified and discussed in detail. Further, various simulation studies have been conducted to demonstrate the microgrid protection challenges associated with different operational strategies. This paper presents key information to researchers and protection engineers to identify microgrid protection challenges and their solutions.

An accurate battery model is essential for precise estimation of battery performance indicators such as state of charge (SoC), state of health (SoH), etc. It helps in determining the optimum energy management and, therefore, optimum utilization of the battery capacity. Some of the battery model parameters may change with the variation of environmental conditions such as operating temperature, and, therefore, accurate temperature compensated model estimation is necessary to minimize the error in battery model and SoC estimation. This paper presents a novel parameters extraction method for the Thevenin equivalent circuit model (ECM) of Li-ion batteries considering their resiliency on temperature effect. The proposed approach represents each of the RC parallel circuits of the Thevenin based equivalent circuit battery model (ECBM) as a first-order linear time-invariant (LTI) system. The resistance and capacitance values for each of the RC circuits in the model have been identified as the parameters of a standard LTI system using the system identification theory and represented them as the temperature compensated model parameters. The proposed model can be applied to various applications such as SoC, SoH estimation, and battery energy management. In order to demonstrate the suitability of the proposed modeling approach, the model is augmented with the conventional extended Kalman filter (EKF) to enable accurate SoC estimation under varying operating temperatures. The accuracy and effectiveness of the proposed modeling approach and its suitability to enhance SoC estimation under a wide operating temperature range (-5C to 45C) have been validated through laboratory experiments in the LabVIEW platform.

This paper presents an adaptive rate of change of frequency (ROCOF) based passive Islanding detection technique (IDT) to overcome the non-detection zone (NDZ) issue and limitation of existing islanding detection techniques. The proposed ROCOF based passive IDT relies on the settings of the phase locked loop (PLL) closed loop control system for frequency, ROCOF and threshold ROCOF value for the PCC relay setting calculations. So, the PLL results in alternate frequency and ROCOF output value with respect to the PLL settings modification. The PLL settings can be different in different types of microgrid systems. Therefore, the proposed adaptive ROCOF based IDT provides a generic solution for islanding detection applications for the safe and reliable operation of different types of microgrid systems. The adaptive ROCOF based IDT is developed and implemented on two different types of the microgrid systems such as (I) generator based microgrid (ii) generator, PV and storage based hybrid microgrid in Matlab/Simpower System. Results showed that the proposed IDT successfully detected the islanding condition even with zero power mismatch and it is fully capable to distinguish between islanding (loss of mains and external fault) and non-islanding (internal fault, load switching, motor starting etc.) conditions with a diverse range of operating conditions.