To sustain the complexity of growing demand, the conventional grid (CG) is incorporated with communication technology like advanced metering with sensors, demand response (DR), energy storage systems (ESS), and inclusion of electric vehicles (EV). In order to maintain local area energy balance and reliability, microgrids (MG) are proposed. Microgrids are low or medium voltage distribution systems with a resilient operation, that control the exchange of power between the main grid, locally distributed generators (DGs), and consumers using intelligent energy management techniques. This paper gives a brief introduction to microgrids, their operations, and further, a review of different energy management approaches. In a microgrid control strategy, an energy management system (EMS) is the key component to maintain the balance between energy resources (CG, DG, ESS, and EVs) and loads available while contributing the profit to utility. This article classifies the methodologies used for EMS based on the structure, control, and technique used. The untapped areas which have scope for investigation are also mentioned.

Review of Energy Management System Approaches in Microgrids

This paper presents, develops, and evaluates a system architecture and its control structure that mitigates impact of the Electric Vehicles’ (EVs) DC fast-charging station on its host weak AC-grid. The charging station incorporates a battery energy storage and (i) limits the imported power based on grid-imposed requirements and (ii) its control system decouples dynamics of the station from those of the grid. The charging station can operate in either grid-connected mode or islanded mode. The dynamic models of the charging station, in both modes, are presented and eigenvalue analyses performed to design the Local Controllers (LCs). Time domain simulation results in PLECS software are presented to verify that the station's internal dynamics, based on the proposed architecture and designed controllers, are sufficiently decoupled from the host AC-grid dynamics.

Grid-Integration of Battery-Enabled DC Fast Charging Station for Electric Vehicles

In recent years, it is seen that there has been a huge expansion in the electric vehicles market aiming to reduce the impact of greenhouse gases. The deployment of an optimal and cost-effective electric vehicle charging stations similar to petrol/diesel stations with advanced control algorithms is necessary for the successful implementation. This review paper gives an overview of electric vehicles and various configurations about the design aspects of charging station. The charging stations are categorized on the basis of power utilized with various optimization algorithms, methods and future directions are presented to have an optimal design. And also, the highlights of grid connected combination of renewable energy based and grid connected, off-grid mode are summarized along with the future scope. Incorporation of renewable energy along with storage systems in the charging station can reduce the high load taken from the grid especially at peak times. By providing an overview of these key areas, the review study aims to provide a deep insight to the industry experts and researchers for future developments.

A technological overview & design considerations for developing electric vehicle charging stations

The usage of electric vehicles (EV) has been increasing over the last few years due to a rise in fossil fuel prices and the rate of increasing carbon dioxide (CO2) emissions. EV-charging stations are powered by existing utility power grid systems, increasing the stress on the utility grid and the load demand at the distribution side. DC grid-based EV charging is more efficient than AC distribution because of its higher reliability, power conversion efficiency, simple interfacing with renewable energy sources (RESs), and integration of energy storage units (ESU). RES-generated power storage in local ESU is an alternative solution for managing the utility grid demand. In addition, to maintain the EV charging demand at the microgrid levels, energy management and control strategies must carefully power the EV battery charging unit. In addition, charging stations require dedicated converter topologies, control strategies, and need to follow set levels and standards. Based on EV, ESU, and RES accessibility, different types of microgrid architecture and control strategies are used to ensure optimum operation at the EV-charging point. Based on the above said merits, this review paper presents different RES-connected architecture and control strategies used in EV-charging stations. It highlights the importance of different charging station architectures with current power converter topologies proposed in the literature. In addition, a comparison of microgrid-based charging station architecture with its energy management, control strategies, and charging converter controls are also presented. The different levels and types of charging stations used for EV charging, in addition to controls and connectors used, are also discussed. An experiment-based energy management strategy was developed to control power flow among the available sources and charging terminals for the effective utilization of generated renewable power. The main motive of the EMS and its control is to maximize the usage of RES consumption. This review also provides the challenges and opportunities in EV-charging, and parameters in selecting appropriate charging stations.

Electric Vehicles Charging Stations’ Architectures, Criteria, Power Converters, and Control Strategies in Microgrids

At present, the electric vehicle (EV) market is developing strongly and widely across many countries around the world. Increasing clean energy infrastructure for EVs is a possible solution to reduce greenhouse gas emissions and help improve air quality in urban areas. Electric vehicles charged by electricity from photovoltaic (PV) systems can produce less emissions than conventional EVs charged by the utility grid. Thus, the combination of solar power and EV charging stations is one of the possible methods to achieve sustainable development in the current EV market. EVs in cities in Vietnam have developed very quickly in recent times, but the charging station infrastructure is still very limited, and most existing charging stations use electricity from the utility grid. In this paper, the optimal configuration of PV-powered EV charging stations is analyzed technically and economically under different solar irradiation conditions in Vietnam. The study results show that the optimal configuration and investment efficiency of PV-powered EV charging stations in each urban area are greatly affected by the solar irradiation value and feed-in tariff (FIT) price of rooftop solar power. In Vietnam, a region with high solar irradiation, such as Ho Chi Minh, is more likely to invest in PV-powered EV charging stations than other areas with lower solar irradiation, such as Hanoi.

Technical Economic Analysis of Photovoltaic-Powered Electric Vehicle Charging Stations under Different Solar Irradiation Conditions in Vietnam

A hybrid microgrid-powered charging station reduces transmission losses with better power flow control in the modern power system. However, the uncoordinated charging of battery electric vehicles (BEVs) with the hybrid microgrid results in ineffective utilization of the renewable energy sources connected to the charging station. Furthermore, planned development of upcoming charging stations includes a multiport charging facility, which will cause overloading of the utility grid. The paper analyzes the following technical issues: (1) the energy management strategy and converter control of multiport BEV charging from a photovoltaic (PV) source and its effective utilization; (2) maintenance of the DC bus voltage irrespective of the utility grid overloading, which is caused by either local load or the meagerness of PV power through its energy storage unit (ESU). In addition, the charge controller provides closed loop charging through constant current and voltage, and this reduces the charging time. The aim of an energy management strategy is to minimize the usage of utility grid power and store PV power when the vehicle is not connected for charging. The proposed energy management strategy (EMS) was modeled and simulated using MATLAB/Simulink, and its different modes of operation were verified. A laboratory-scale experimental prototype was also developed, and the performance of the proposed charging station was investigated.

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Photovoltaic Integrated Hybrid Microgrid Structured Electric Vehicle Charging Station and Its Energy Management Approach

Road transport is becoming increasingly electric as it becomes more environmentally friendly. A green transportation system includes solar arrays along the roadside, encouraging the eco-friendly EV charging system. This paper proposes a road-side photovoltaic system to charge the batteries of slow-moving electric vehicles using a five-leg inverter. The five-legged inverter, which utilizes a stand-alone PV system to drive the charging pads, enhances the probability of achieving the sustainability goal. The limitations of the conventional H-bridge inverter, such as its more prominent design and higher number of switches or straightforward design and restricted power level, are addressed by this converter. The proposed 3.3 kW, 85 kHz inverter energizes the four transmitter pads while a receiver pad moves over the transmitter pads and inductively extracts the power. The d.c.-d.c. converter is used to feed the power to the proposed inverter. The P and O-based MPPT algorithm with a tuned PI controller is used to generate the driving pulses of the d.c.-d.c. converter. The signals are generated based on the voltage and current output of the solar panel output. This control algorithm ensures the stability of the system output response. Additionally, the tuned d.c.-d.c. converter achieves maximum efficiency independent of the load resistance. The system maintains constant power transfer profile concerning load resistance variations. The 520*520 mm Double D-pad transmits the power, while the series-series compensation network assists the charging pads in achieving resonance. The developed systems’ nominal charging voltage and current are 144 V, 20 A, with an equivalent battery resistance of 7.2 Ω.

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Solar-powered five-leg inverter-driven quasi-dynamic charging for a slow-moving vehicle

Business organizations need to sustain their performance in ever increasing volatile business environment. Human Capital is the key to business success. Managing human recourses requires vital knowledge and information on human behaviours. This article presents Emotional Intelligence and Conflict handling behaviour of employees of different age groups. The study was undertaken in automobile and information technology industries in Chennai to measure among the employees the impact of age on emotional intelligence and conflict management. Emotional Quotient Test (Chadha, 2006), Thomas –Kilmann Conflict Mode Instrument (1974) were used for collecting data and statistical tests were used for analysis. Data analysis revealed that employees above 35 years of age had emotional maturity compared with other age groups. In handling conflicts, a pattern emerging from the study was identified: employees below 25 years of age were unassertive, employees between 30 -35 years of age were collaborative and employees above 35 years of age were competing.

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Dominic A. Savio

Papers

Photovoltaic Integrated Hybrid Microgrid Structured Electric Vehicle Charging Station and Its Energy Management Approach

Solar-powered five-leg inverter-driven quasi-dynamic charging for a slow-moving vehicle

Emotional Intelligence and Modes of Conflict Management of Employees of Different Age Groups