Development of Wind-Powered Smart Transition Electric Vehicle Charging Station

Mohanty S., Pati S., Kar S.K.

Electricity from renewable energy is certainly the most prominent alternative to deliver power to remote locations; however, its reliability is affected by the intermittency of the renewable source. A smart load technology called ‘electric spring (ES)’ can compensate for the intermittency and thereby maintain the voltage level constant for critical loads with an efficient and reliable control approach. This paper suggests wind energy-fed generation as the only and primary source for an isolated remote microgrid. The voltage level of the system remained unaltered by deploying a voltage source converter-based ES with a novel artificial neural network-based fuzzy controller. The novelty of the system is that it can operate significantly under varying load, variable torque, and varying wind speed conditions by exchanging power between critical and non-critical loads. Further simulation results ensure the credibility of the electric spring–artificial neural network-based fuzzy controller system in terms of stability and performance parameters such as settling time, rise time, and maximum overshoot. Additionally, the total harmonic distortion of the system is found to be well within the boundary of the acceptable range that proclaims its feasibility and applicability in a real-world scenario.

Saritha M., Manitha P.V.

Ankita, Jarial R.K.

Kaymanesh A., Chandra A.

This article introduces a novel configuration of electric spring (ES) based on the modified five-level packed u-cell (MPUC5) inverter for mitigating harmonics and voltage fluctuations at various points of a grid with unstable generated power from distributed renewable energy sources. Immanent merits of the proposed configuration include, but are not limited to, halved dc-links voltages, boost mode operation, the possibility of higher power applications, smooth five-level voltage waveform with low total harmonic distortion (THD) index, the smaller size of output low-pass filter, and low switching frequency. The operation principles, design procedure, and configuration of the MPUC5-based ES (MPUC5-ES) are also presented. Besides, a simple and yet efficient controller without any extra control loop for regulating dc bus voltages has been proposed. Finally, the introduced multilevel ES is tested through extensive simulation and experimental studies to confirm its dynamic and steady-state performances in various operation modes in a weak grid fed by both conventional and intermittent renewable energy sources.

Norouzi M., Aghaei J., Pirouzi S., Niknam T., Fotuhi-Firuzabad M., Shafie-khah M.

• Electric spring model is developed for demand-side management. • Flexibility of EVs is used to increase wind energy. • EVs and electric spring are modeled as flexibility tools to transfer energy. • The paper deals with day-ahead operation of smart microgrids. • Hybrid stochastic/robust optimization is proposed to handle uncertainty. Electric spring (ES) as a novel concept in power electronics has been developed for the purpose of dealing with demand-side management. In this paper, to conquer the challenges imposed by intermittent nature of renewable energy sources (RESs) and other uncertainties for constructing a secure modern microgrid (MG), the hybrid distributed operation of ESs and electric vehicles (EVs) parking lot is suggested. The proposed approach is implemented in the context of a hybrid stochastic/robust optimization (HSRO) problem, where the stochastic programming based on unscented transformation (UT) method models the uncertainties associated with load, energy price, RESs, and availability of MG equipment. Also, the bounded uncertainty-based robust optimization (BURO) is employed to model the uncertain parameters of EVs parking lot to achieve the robust potentials of EVs in improving MG indices. In the subsequent stage, the proposed non-linear problem model is converted to linear approximated counterpart to obtain an optimal solution with low calculation time and error. Finally, the proposed power management strategy is analyzed on 32-bus test MG to investigate the hybrid cooperation of ESs and EVs parking lot capabilities in different cases. The numerical results corroborate the efficiency and feasibility of the proposed solution in modifying MG indices.

Zhang X., Zheng Z.

With the increasing of the grid-connected capacity of renewable energy such as wind energy and solar energy, its instability, intermittence and uncontrollability have a serious impact on the stable operation of power system, such as voltage fluctuation, frequency flicker, etc. Therefore, Electric Spring (ES) system has become a current research hotspot. Aiming at the deficiencies of the resonance control strategy, a control method that combines quasi-proportional resonance (QPR) control and repetitive control is proposed. The quasi proportional resonance control is used to realize the tracking without static error, and the internal model principle of repetitive control is used to suppress the periodic disturbance of the grid voltage, so as to improve the power quality of the grid. Compared with the traditional quasi proportional resonant control, the introduction of repetitive control can effectively improve the steady-state accuracy, reduce the system harmonic and enhance the ability of anti-harmonic interference. The modeling of ES and the design method of repetitive controller parameters are discussed in detail. The simulation model is built using MATLAB / Simulink, and the ES experimental platform is built with dSPACE as the control core, the results verify the feasibility and effectiveness of the proposed control strategy.

Ashraf S., Alfandi O., Ahmad A., Khattak A.M., Hayat B., Kim K.H., Ullah A.

Due to unavoidable environmental factors, wireless sensor networks are facing numerous tribulations regarding network coverage. These arose due to the uncouth deployment of the sensor nodes in the wireless coverage area that ultimately degrades the performance and confines the coverage range. In order to enhance the network coverage range, an instance (node) redeployment-based Bodacious-instance Coverage Mechanism (BiCM) is proposed. The proposed mechanism creates new instance positions in the coverage area. It operates in two stages; in the first stage, it locates the intended instance position through the Dissimilitude Enhancement Scheme (DES) and moves the instance to a new position, while the second stage is called the depuration, when the moving distance between the initial and intended instance positions is sagaciously reduced. Further, the variations of various parameters of BiCM such as loudness, pulse emission rate, maximum frequency, grid points, and sensing radius have been explored, and the optimized parameters are identified. The performance metric has been meticulously analyzed through simulation results and is compared with the state-of-the-art Fruit Fly Optimization Algorithm (FOA) and, one step above, the tuned BiCM algorithm in terms of mean coverage rate, computation time, and standard deviation. The coverage range curve for various numbers of iterations and sensor nodes is also presented for the tuned Bodacious-instance Coverage Mechanism (tuned BiCM), BiCM, and FOA. The performance metrics generated by the simulation have vouched for the effectiveness of tuned BiCM as it achieved more coverage range than BiCM and FOA.

Ahmad A., Ullah A., Feng C., Khan M., Ashraf S., Adnan M., Nazir S., Khan H.U.

In this paper, we proposed LCX-MAC (local coordination X-MAC) as an extension of X-MAC. X-MAC is an asynchronous duty cycle medium access control (MAC) protocol. X-MAC used one important technique of short preamble which is to allow sender nodes to quickly send their actual data when the corresponding receivers wake up. X-MAC node keeps sending short preamble to wake up its receiver node, which causes energy, increases transmission delay, and makes the channel busy since a lot of short preambles are discarded, as these days Internet of Things (IoT) healthcare with different sensor nodes for the healthcare is time-critical applications and needs a quick response. A possible improvement over X-MAC is that local information of each node will share with its neighbour node. This local information exchanged will cause much less overhead than in the nodes which are synchronized. To calculate the effect of this the local coordination on X-MAC in this paper, we built an analytical model of LCX-MAC that incorporates the local coordination in X-MAC. The analytical results show that LCX-MAC outperformed X-MAC and X-MAC/BEB in terms of throughput, delay, and energy.

Nour M., Chaves-Ávila J.P., Magdy G., Sánchez-Miralles Á.

There is a continuous and fast increase in electric vehicles (EVs) adoption in many countries due to the reduction of EVs prices, governments’ incentives and subsidies on EVs, the need for energy independence, and environmental issues. It is expected that EVs will dominate the private cars market in the coming years. These EVs charge their batteries from the power grid and may cause severe effects if not managed properly. On the other hand, they can provide many benefits to the power grid and get revenues for EV owners if managed properly. The main contribution of the article is to provide a review of potential negative impacts of EVs charging on electric power systems mainly due to uncontrolled charging and how through controlled charging and discharging those impacts can be reduced and become even positive impacts. The impacts of uncontrolled EVs charging on the increase of peak demand, voltage deviation from the acceptable limits, phase unbalance due to the single-phase chargers, harmonics distortion, overloading of the power system equipment, and increase of power losses are presented. Furthermore, a review of the positive impacts of controlled EVs charging and discharging, and the electrical services that it can provide like frequency regulation, voltage regulation and reactive power compensation, congestion management, and improving power quality are presented. Moreover, a few promising research topics that need more investigation in future research are briefly discussed. Furthermore, the concepts and general background of EVs, EVs market, EV charging technology, the charging methods are presented.

Crozier C., Morstyn T., McCulloch M.

A rapid increase in the number of electric vehicles is expected in coming years, driven by government incentives and falling battery prices. Charging these vehicles will add significant load to the electricity network, and it is important to understand the impact this will have on both the transmission and distribution level systems, and how smart charging can alleviate it. Here we analyse the effects that charging a large electric vehicle fleet would have on the power network, taking into account the spatial heterogeneity of vehicle use, electricity demand, and network structure. A conditional probability based method is used to model uncontrolled charging demand, and convex optimisation is used to model smart charging. Stochasticity is captured using Monte Carlo simulations. It is shown that for Great Britain’s power system, smart charging can simultaneously eliminate the need for additional generation infrastructure required with 100% electric vehicle adoption, while also reducing the percentage of distribution networks which would require reinforcement from 28% to 9%. Discussion is included as to how far these results can be extended to other power systems.

Chen T., Liu H., Lee C., Hui S.Y.

With the electric spring (ES) being practically evaluated by utility companies in power grids, there is a need to explore its practical implementation aspects of general applications. In this paper, we propose three interior angle control principles for the ES. Systematic analysis and comparative study show that these three control principles lead to different smart load (SL) performance. The operating characteristic curves and distinctive features/advantages of the SL using these three control methods are analyzed and explained. A generalized controller structure suitable for the implementations of all these three angle control schemes is presented. It is practically shown that the same controller structure can be programmed to implement these three angle control strategies. This outcome is the first step to realize a programmable ES-based SL for providing multiple functions.

Sun X., Li Z., Wang X., Li C.

To reduce the dependence on oil and environmental pollution, the development of electric vehicles has been accelerated in many countries. The implementation of EVs, especially battery electric vehicles, is considered a solution to the energy crisis and environmental issues. This paper provides a comprehensive review of the technical development of EVs and emerging technologies for their future application. Key technologies regarding batteries, charging technology, electric motors and control, and charging infrastructure of EVs are summarized. This paper also highlights the technical challenges and emerging technologies for the improvement of efficiency, reliability, and safety of EVs in the coming stages as another contribution.

Yap K.Y., Sarimuthu C.R., Lim J.M.

This study paper presents a comprehensive review of virtual inertia (VI)-based inverters in modern power systems. The transition from the synchronous generator (SG)-based conventional power generation to converter-based renewable energy sources (RES) deteriorates the frequency stability of the power system due to the intermittency of wind and photovoltaic (PV) generation. Unlike conventional power generation, the lack of rotational inertia becomes the main challenge to interface RES with the electrical grid via power electronic converters. In the past several years, researchers have addressed this issue by emulating the behavior of SG mathematically via pulse width modulation (PWM) controller linked to conventional inverter systems. These systems are technically known as VI-based inverters, which consist of virtual synchronous machine (VSM), virtual synchronous generator (VSG), and synchronverter. This paper provides an extensive insight into the latest development, application, challenges, and prospect of VI application, which is crucial for the transition to low-carbon power system.

Norouzi M., Aghaei J., Pirouzi S., Niknam T., Lehtonen M.

This study presents a new solution to cope with the intermittent nature of renewable generations (RGs) and facilitate the integration of RGs in the smart active distribution network. Electric spring (ES) as one of the most influential solutions in demand-side management is proposed as a flexible resource for flexible operation of grid-connected microgrid against other sources of uncertainty such as forecasted load demand and energy price as well as the RGs output. This innovative approach has been considered in the context of a stochastic problem by presenting the static model of ES for the first time. The modelling of uncertainties is done by the roulette wheel mechanism as a scenario generation process and backward method for reducing the number of scenarios. In the proposed optimisation problem, the objective function is minimising the operating cost and voltage deviation as well as maximising system flexibility, subject to the AC power flow, ES and RGs constraints and technical system limitations. Finally, the proposed solution is tested on 33-bus IEEE test system by the general algebraic modelling system software. The case studies demonstrate the efficiency of the proposed ES model in different simulation and experimental cases in providing flexi-renewable microgrid.

Zhang Z., Xie C., Tong R., Gao S.

By comprehensively analyzing the effective working voltage range of electric springs (ESs), this paper proposes a new control strategy to improve the absorption capacity of ES-based flexible loads for mains voltage fluctuations; thus, enhancing the stability of the microgrid fed by intermittent renewables. Analogous to a mechanical spring, the effective working voltage range of ESs is also restricted by the electric elasticity limit (EEL). In specific circumstances, the ES-based flexible load is incapable of dealing with excessive fluctuations of mains voltage caused by intermittent renewable energy sources. Accordingly, this paper investigates the impact of key parameters on the EEL of ESs, such as the distribution line, the voltage reference, and the loads. Besides, by adjusting the proportion between the critical and the noncritical loads, this paper proposes and implements an EEL controller to regulate the absorption capacity of ES-based flexible loads for mains voltage fluctuations; thus, effectively ensuring the voltage stability of critical loads. Finally, the simulated and experimental results are both given to verify the theoretical analysis for ES-based flexible loads and the feasibility of the proposed EEL controller.

Giri J., Mishra N.K., Tapde A.

Wind energy is a fast-growing source of clean energy, and this chapter addresses its integration challenges, including grid connectivity, wind variability, and turbine placement. A complex controller, electrical converter, and generator are required when wind turbines are connected to the electrical grid in order to manage the variable power generation brought on by different wind speeds. It is essential to examine control strategies such as phase lock loops, pitch controllers, and passive stalls to maximize output and maintain steady voltage. Also discussed is the classification of Wind Energy Conversion Systems (WECS) into offshore and land-based setups, which highlight the advantages of offshore systems, such as their high-power output and confined footprint. Aside from that, it examines the physical and operational challenges that come with downwind rotors, including extreme cyclic loads on the blades and the impact of variable wind on rotor mechanics. Power stability can be enhanced by integrating WECS with grid systems using innovative technologies like HVDC and energy storage systems.

Samal K.B., Bhatta A., Pati S., Sharma R.