Voltage Oriented Controller based Vienna Rectifier for Electric Vehicle Charging Stations

Vienna rectifiers have gained popularity in recent years for AC to DC power conversion for many industrial applications such as welding power supplies, data centers, telecommunication power sources, aircraft systems, and electric vehicle charging stations. The advantages of this converter are low total harmonic distortion (THD), high power density, and high efficiency. Due to the inherent current control loop in the voltage-oriented control strategy proposed in this paper, good steady-state performance and fast transient response can be ensured. The proposed voltage-oriented control of the Vienna rectifier with a PI controller (VOC-VR) has been simulated using MATLAB/Simulink. The simulations indicate that the input current THD of the proposed VOC-VR system was below 3.27% for 650V and 90A output, which is less than 5% to satisfy the IEEE-519 standard. Experimental results from a scaled-down prototype showed that the THD remains below 5% for a wide range of input voltage, output voltage, and loading conditions (up to 2 kW). The results prove that the proposed rectifier system can be applied for high power applications such as DC fast-charging stations and welding power sources

Dynamic modeling of power network-integrated wind turbine

This paper presents the performance investigation of voltage and current for dynamic model of the wind turbine. In this study, the various numbers of wind turbine speed are applied in the simulation. This treatment is intended to see how much influence the turbine speed has on the voltage and current output. IEEE 14 bus system is integrated to the wind turbine in order to observe the impact of on-grid connection to the voltage and current performance. How to model wind turbine in PSCAD simulation software also discussed in this paper. The detail of supporting components in designing a wind turbine system and their functions are also explained. Several values of turbine speed are also considered in this paper as a study material in seeing the performance of wind turbines. The relationship between wind speed and pitch angle will also be discussed to ensure that the wind turbine is not damaged. In order to prove the accuracy of the simulation model, the obtained measurement generation of active power from the wind turbine is matched with the manual calculation. Based on the various wind speed values that have been tested, this can be the basis for the application of wind turbine (renewable energy) design development for further research

A comprehensive review on system architecture and international standards for electric vehicle charging stations

Electric Vehicles (EVs) are rapidly becoming an important facet in the drive for attaining sustainable energy goals. However, EV sales still constitute only a small proportion of vehicles in most countries. The expansion of DC fast-charging network will facilitate a sustainable transportation revolution by offering end-user a versatile choice to charge EVs for longer journeys. Power converters play a significant role in the design and operation of EV charging stations. Modern technologies in charging stations are promising, where state-of-the-art research allows idle batteries or EVs to operate as distributed energy sources. However, it is always important to ensure input current harmonics and power factors are within the standard specification. Solid-state switch-mode power converters have reached a level of maturity with regards to the improvement in power quality and precisely regulating voltage levels during bidirectional power flow operation. This paper presents an exposition of EV charging systems, including incentives for development, structures, power converters, standards, industrial applications, and emerging trends. Furthermore, state-of-the-art technologies, including both academic and real-world EV charging technologies, have been carefully chosen, and a quantitative assessment of the technologies has been provided in this paper

Correction: Saharuddin, N.Z.; et al. A Power System Network Splitting Strategy Based on Contingency Analysis. Energies 2018, 11, 434

The authors wish to make the following corrections to this paper[...

A power system network splitting strategy based on contingency analysis

This paper proposes a network splitting strategy following critical line outages based on N-1 contingency analysis. Network splitting is the best option for certain critical outages when the tendency of severe cascading failures is very high. Network splitting is executed by splitting the power system network into feasible set of islands. Thus, it is essential to identify the optimal splitting solution (in terms of minimal power flow disruption) that satisfies certain constraints. This paper determines the optimal splitting solution for each of the critical line outage using discrete evolutionary programming (DEP) optimization technique assisted by heuristic initialization approach. Heuristic initialization provides the best initial cutsets which will guide the optimization technique to find the optimal splitting solution. Generation-load balance and transmission line overloading analysis are carried out in each island to ensure the steady state stability is achieved. Load shedding scheme is initiated if the power balance criterion is violated in any island to sustain the generation-load balance. The proposed technique is validated on the IEEE 118 bus system. Results show that the proposed approach produces an optimal splitting solution with lower power flow disruption during network splitting execution

Firefly optimised PID control for upper extremity rehabilitation robot

This paper proposes a meta-heuristic technique to optimize controller parameters for upper extremity rehabilitation robot. The exoskeleton used in this study is a three-degrees-of-freedom system facilitating shoulder and elbow joint movements. The robot exoskeleton is designed for facilitating shoulder abduction/ adduction, extension/ flexion, horizontal external/ internal rotation and elbow extension/ flexion. Zeigler-Nichols is a conventional technique for setting the PID parameters produces large overshoots, high rise-time and settling-time in the system. To address such issues nature-inspired Firefly optimization algorithm for the parameterizing 2-DOF-PID controller has been proposed. A comparative analysis between two algorithms has been done for a 3-DOF upper extremity rehabilitation robot. For analysis, four different objective functions ISE (integral square error), ITSE (integral time square error), IAE (integral absolute error) and ITAE (integral time absolute error) have been used. The results of the analysis showed that Firefly algorithm with ITAE as objective functions performs better in terms of overshoot, rise-time and settling-time

Hard Switching Characteristics of SiC and GaN Devices for Future Electric Vehicle Charging Stations

Wide bandgap (WBG) semiconductors offer better switching and lower losses, and it is not uncommon to utilize them for high power density, high-efficiency applications. Gallium nitride (GaN) and Silicon carbide (SiC) are the most common WBG materials that are responsible for major switching level changes relative to silicon (Si) devices. This paper explores the contrast of performance between Si, SiC, and GaN devices. The output performance of Si, SiC, and GaN power devices includes efficiency, energy bandgap, thermal conductivity, carrier mobility, saturation speed, power density, switching characteristics, and conduction losses. This article also proposes a Vienna rectifier with GaN materials, which operates as a front-end rectifier on a high-density battery charger targeted at high-performance applications such as electric vehicle charging stations, aircraft applications, and welding power sources. The system would reduce the total harmonics distortion (THD) to less than 5%, and the power factor would be increased to unity to satisfy the IEEE-519 standard

Integrated database approach in multi-objective network reconfiguration for distribution system using discrete optimisation techniques

Reconfiguring the link between buses is a crucial task to enhance the distribution system performance. Reconfiguration is a complex combinatorial process due to numerous feasible solutions. Therefore, to consistently find global optimum solutions within a short span of time is a challenging task. One of the factors that cause time consumption in finding optimal network configurations is the elimination of non-radiality network solutions during the optimisation process. To address this issue, this work proposes to store pre-determined network radiality solutions in a database. These sets of solutions are used in the network reconfiguration optimisation by a discrete evolutionary programming and a discrete evolutionary particle swarm optimisation techniques. These optimisation methods are based on a multi-objective problem which minimises power loss, voltage deviation, and a number of switching actions. Moreover, the quality of the solutions is measured in terms of computational time and consistency. To demonstrate the efficiency of the proposed technique, a comparative assessment is carried out on 33-bus and 118-bus distribution systems. It is found that the proposed technique outperforms other existing methods in terms of quality of the solutions