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 presents an adaptive virtual capacitance control method for distributed generation (DGs) in an islanded microgrid to mitigate the voltage harmonics at the point of common coupling (PCC). To achieve the control target, the proposed method emulates the inverter output capacitance at the dominant harmonic frequency to compensate for the mismatched voltage drop on the line impedance. In addition, the virtual capacitance at the fundamental frequency is regulated to improve the reactive power sharing performance of the inverter units. The proposed capacitance control method is developed based on simple integral controllers without prior knowledge of the feeder impedances and local nonlinear load currents. By continuously adjusting the inverter output capacitance, the microgrid power sharing performance and voltage quality are ensured despite any load changes. The effectiveness and superiority of the proposed strategy are theoretically analyzed and verified.

Accurate Reactive Power Sharing and Harmonic Mitigation in Islanded Microgrids Using Adaptive Virtual Capacitance

Robust finite-control-set model predictive control for voltage source inverters against LC-filter parameter mismatch and variation

This paper presents an enhanced compensation strategy for distributed generation (DG) systems to simultaneously achieve accurate power sharing and harmonics compensation at the point of common coupling (PCC). In the proposed control strategy, the output impedance is modified at the fundamental and harmonic frequencies to compensate for the line impedance mismatches among DG units, which results in accurate power sharing. In addition, load harmonic currents are effectively adjusted by the DG units to effectively compensate the PCC voltage harmonics. Additionally, the DG equivalent impedance is regulated adaptively to ensure accurate harmonic power sharing even in the presence of sudden load changes. Furthermore, a distributed communication network is adopted instead of a central controller to increase the reliability and stability of the microgrid system. The proposed control strategy is applied to a prototype microgrid system, and its effectiveness and reliability are experimentally validated.

Impedance-based harmonics compensation with accurate harmonic power sharing in distorted microgrids

This study presents a distributed-based control method to provide accurate harmonic power sharing for islanded microgrids. The proposed method requires simple communication network through which the DG unit uses local and its neighbors' information to execute the control algorithm. In the proposed method, a distributed adaptive virtual impedance controller is developed to realize accurate harmonic power sharing for the islanded microgrids regardless of load changes. The proposed method is quite easily implemented in practice because the information such as the line impedances, load powers, and the detailed microgrid configuration is needless. Also, the feasibility and effectiveness of the proposed method are validated via digital simulation.

A Distributed Harmonic Power Sharing Strategy for Islanded Microgrids

This paper develops the high-efficiency drive system of the small-size electric vehicles (EVs) driven by the brushed dc motors. A power circuit for driving the dc motor is designed with the H-bridge circuit and buck converter by considering both the efficiency and cost. In order to change smoothly the rotating direction of dc motor driven by the proposed power circuit, an operating sequence for both the field current and the armature voltage according to an accelerator pedal angle is suggested. Through the simulation studies and experimental results with the low-cost 8-bit AVR, the performances of the proposed methods are verified.

http://www.ndsl.kr/soc_img/society/kiee/DHJGII/2012/v61n11/DHJGII_2012_v61n11_1634.pdf

Hong-Hee Lee

Papers

Accurate Reactive Power Sharing and Harmonic Mitigation in Islanded Microgrids Using Adaptive Virtual Capacitance

Robust finite-control-set model predictive control for voltage source inverters against LC-filter parameter mismatch and variation

Impedance-based harmonics compensation with accurate harmonic power sharing in distorted microgrids

A Distributed Harmonic Power Sharing Strategy for Islanded Microgrids

Development of High-Efficiency Drive System of DC Motors for Tracking Small-Size Electric Vehicles