A communication infrastructure is an essential part to the success of the emerging smart grid. A scalable and pervasive communication infrastructure is crucial in both construction and operation of a smart grid. In this paper, we present the background and motivation of communication infrastructures in smart grid systems. We also summarize major requirements that smart grid communications must meet. From the experience of several industrial trials on smart grid with communication infrastructures, we expect that the traditional carbon fuel based power plants can cooperate with emerging distributed renewable energy such as wind, solar, etc, to reduce the carbon fuel consumption and consequent green house gas such as carbon dioxide emission. The consumers can minimize their expense on energy by adjusting their intelligent home appliance operations to avoid the peak hours and utilize the renewable energy instead. We further explore the challenges for a communication infrastructure as the part of a complex smart grid system. Since a smart grid system might have over millions of consumers and devices, the demand of its reliability and security is extremely critical. Through a communication infrastructure, a smart grid can improve power reliability and quality to eliminate electricity blackout. Security is a challenging issue since the on-going smart grid systems facing increasing vulnerabilities as more and more automation, remote monitoring/controlling and supervision entities are interconnected.

https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1315&context=electricalengineeringfacpub

A Survey on Smart Grid CommunicationInfrastructures: Motivations, Requirements andChallenges

A recurrent neural network based health indicator for remaining useful life prediction of bearings

Electrifying transportation is a promising approach to alleviate the climate change issue. The adoption of electric vehicle into market has introduced significant impacts on various fields, especially the power grid. Various policies have been implemented to foster the electric vehicle deployment and the increasing trend of electric vehicle adoption in the recent years has been satisfying. The continual development of electric vehicle power train, battery and charger technologies have further improved the electric vehicle technologies for wider uptake. Despite the environmental and economical benefits, electric vehicles charging introduce negative impacts on the existing network operation. Appropriate charging management strategies can be implemented to cater for this issue. Furthermore, electric vehicle integration in the smart grid can bring many potential opportunities, especially from the perspective of vehicle-to-grid technology and as the solution for the renewable energy intermittency issue. This paper reviews the latest development in electric vehicle technologies, impacts of electric vehicle roll out and opportunities brought by electric vehicle deployment.

A review on the state-of-the-art technologies of electric vehicle, its impacts and prospects

This paper reviews state of the art maximum power point tracking (MPPT) algorithms for wind energy systems. Due to the instantaneous changing nature of the wind, it is desirable to determine the one optimal generator speed that ensures maximum energy yield. Therefore, it is essential to include a controller that can track the maximum peak regardless of wind speed. The available MPPT algorithms can be classified as either with or without sensors, as well as according to the techniques used to locate the maximum peak. A comparison has been made between the performance of different MPPT algorithms on the basis of various speed responses and ability to achieve the maximum energy yield. Based on simulation results available in the literature, the optimal torque control (OTC) has been found to be the best MPPT method for wind energy systems due to its simplicity. On the other hand, the perturbation and observation (P&O) method is flexible and simple in implementation, but is less efficient and has difficulties determining the optimum step-size.

A review of maximum power point tracking algorithms for wind energy systems

Impedance networks cover the entire of electric power conversion from dc (converter, rectifier), ac (inverter), to phase and frequency conversion (ac-ac) in a wide range of applications. Various converter topologies have been reported in the literature to overcome the limitations and problems of the traditional voltage source, current source as well as various classical buck-boost, unidirectional, and bidirectional converter topologies. Proper implementation of the impedance-source network with appropriate switching configurations and topologies reduces the number of power conversion stages in the system power chain, which may improve the reliability and performance of the power system. The first part of this paper provides a comprehensive review of the various impedance-source-networks-based power converters and discusses the main topologies from an application point of view. This review paper is the first of its kind with the aim of providing a “one-stop” information source and a selection guide on impedance-source networks for power conversion for researchers, designers, and application engineers. A comprehensive review of various modeling, control, and modulation techniques for the impedance-source converters/inverters will be presented in Part II.

Impedance-Source Networks for Electric Power Conversion Part I: A Topological Review

This paper proposes an enhanced model predictive current control (MPCC) scheme to reduce current harmonics and computational burden for two-level symmetrical six-phase voltage source inverter (VSI) without using weighting factors. In the proposed scheme, 19 virtual vectors are used as input control set to suppress harmonic contents of output currents. The optimal voltage vector among the 19 virtual voltage vector is selected based on a combination of a pre-selection algorithm and new cost function without using weighting factors. Therefore, the computational burden of proposed scheme is significantly reduced. The simulation results are given to verify the effectiveness of the proposed scheme.

An Enhanced Load Current Control Scheme to Reduce Computational Burden for Two-Level Symmetrical Six-Phase VSI

In this paper, an intelligent control scheme based on fuzzy proportional-integral-derivative controller (FPIDC) is proposed for PCC voltage harmonic compensation in islanded microgrid. The proposed FPIDC method is composed of a closed-loop control of the virtual impedance at harmonic frequency to absorb the harmonic current from the nonlinear load, control harmonic sharing between distributed generators. As a result, the PCC voltage quality is improved with the total harmonic distortion (THD) significantly reduced. With the feedback of the PCC voltage and well-designed fuzzy controller, the uncertainty and unstable value of proportional-integral-derivative (PID) parameters are removed by adaptive tuning. Therefore, the PCC voltage quality is improved smoothly, and the system becomes more stable even load condition is changed. Compared with the traditional PID controller, the dynamic response and stability of the microgrid system are improved with the proposed FPIDC. The comparison and analysis of the proposed control with the conventional control are carried out to verify the superiority of the proposed method.

Fuzzy PID Controller for PCC Voltage Harmonic Compensation in Islanded Microgrid

In this paper, an intelligent control scheme based on Fuzzy PID controller is proposed for accurate power sharing in DC Microgrid. The proposed Fuzzy PID controller is designed with the aid of a closed loop control based on per unit power of each distributed generator (DG), and accurate power sharing is successfully realized in proportional to each DG’s power rating regardless of the line resistance difference or the load change. Thanks to Fuzzy PID controller, the dynamic response becomes faster and the stability of the microgrid system is improved in comparison to conventional PID controller. The superiority of the proposed method is analyzed and verified by simulation in Matlab and Simulink.

https://www.koreascience.kr:443/article/CFKO201920461759677.pdf

Fuzzy PID Controller for Accurate Power Sharing in DC Microgrid

This paper proposes an enhanced virtual impedance control strategy to achieve the accurate harmonic power sharing as well as PCC harmonic compensation at the same time without degrading the reactive power sharing accuracy. The proposed control strategy is achieved by modifying the virtual impedances at fundamental and harmonic frequencies simultaneously, and the mismatched impedance between distribution generators (DGs)is effectively compensated with the improved fundamental and harmonic power sharing performance. Based on inverter modelling, the comparative frequency domain of the inverter output impedance and controller is analyzed. And also, the central controller is removed by means of the distributed communication network, which reduces the system complexity and increases the stability and reliability of the whole microgrid. The reliability and effectiveness of the proposed control strategy are experimentally validated together with theoretical analysis.

An Effective PCC Voltage Harmonic Compensation and Harmonic Power Sharing in Islanded Microgrid

This paper proposes virtual shunt filter to achieve the harmonic compensation at the point of common coupling (PCC) and virtual damping resistance to damp microgrid resonance. The proposed control objective is achieved by modifying the virtual impedances at both fundamental and harmonic frequencies to compensate the mismatched impedance and voltage distortion at the PCC. By actively inserting the virtual damping resistance at high frequency, the virtual damping impedance damps the microgrid resonance and rejects the disturbances, which increases the stability and reliability of the microgrid. Based on the system closed-loop model, the behavior of the inverter output impedance is analyzed in detail with the proposed control method. The effectiveness and feasibility of the virtual shunt filter and virtual damping resistance are verified by theoretical analysis and experimentally results.

Hong-Hee Lee

Papers

An Enhanced Load Current Control Scheme to Reduce Computational Burden for Two-Level Symmetrical Six-Phase VSI

Fuzzy PID Controller for PCC Voltage Harmonic Compensation in Islanded Microgrid

Fuzzy PID Controller for Accurate Power Sharing in DC Microgrid

An Effective PCC Voltage Harmonic Compensation and Harmonic Power Sharing in Islanded Microgrid

Resonance Mitigation and Harmonics Compensation in Islanded Microgrids via Virtual Damping Resistance and Virtual Shunt Filter