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

Bearing fault detection with the aid of the vibration signals is presented. In this paper, time-domain features are extracted to indicate bearing fault, which collected from tri-axial vibration signal. Decision tree is chosen as an effective diagnostic tool to obtain bearing status. The paper also introduces principal component analysis (PCA) algorithm to reduce training data dimension and remove irrelevant data. Both original data and PCA-based data are used to train C4.5 decision tree models. Then, the result of PCA-based decision tree is compared with normal decision tree to get the best performance of classification process.

Bearing Diagnosis Using Time-Domain Features and Decision Tree

A new method to solve a Lyapunov equation for a discrete delay system is proposed. Using this method, a Lyapunov equation can be solved from a simple linear equation and N -th power of a constant matrix, where N is the state delay. Combining a Lyapunov equation and frequency domain stability, a new stability condition is proposed for a discrete state delay system whose state delay is not exactly known but only known to lie in a certain interval.

/pdf/necessary-and-sufficient-stability-condition-of-discrete-2rnj77ifte.pdf

Necessary and Sufficient Stability Condition of Discrete State Delay Systems

With integration of a battery energy storage system (BESS) into the wind power system, the wind power variation can be mitigated to dispatch a constant power to the grid. To effectively supply the constant power dispatch to the grid with a limited BESS, the power dispatch capability should be defined primarily at beginning of each dispatching interval to cooperate with the transmission system operator. This study introduces a method to determine the power dispatch capability of a wind-battery hybrid power system with the minimal battery capacity. The power dispatch capability is decided under the condition that the battery power is maintained below its rating and that the state of charge of the battery is guaranteed within a safe range. For economic BESS operation, the battery capacity, including the power and energy ratings, is also determined cost-effectively to obtain the constant power dispatch. Based on the long-term wind power profile, the authors develop the determination process to minimise the battery capacity which ensures that the BESS sufficiently mitigates wind power variation to dispatch the constant power into grid under all wind conditions. To evaluate the proposed determination method, a case study is carried out with a 3-MW wind turbine generator and real wind speed data measured on Jeju Island in Korea.

https://ietresearch.onlinelibrary.wiley.com/doi/epdf/10.1049/iet-gtd.2015.0078

Effective power dispatch capability decision method for a wind-battery hybrid power system

This paper proposes an improved current controller to achieve a high current performance in grid connected converter under distorted grid voltage condition. The proposed control scheme is employed in synchronously rotating reference frame that consists of a conventional proportional-integral (PI) controller plus a resonant (R) controller tuned at six times of grid frequency. The complexity of the proposed control algorithm is greatly reduced because a single resonant controller is enough to eliminate effectively both negative fifth and positive seventh harmonic components in current, which are caused by distorted grid voltage. The control strategy is analyzed and design of resonant controller in discrete form will also be presented. Simulation and experimental results are presented to validate the feasibility of the proposed control algorithm. (6 pages)

Improvement of current performance for grid connected converter under distorted grid condition

This paper proposes a new topology named a modified switched-capacitor Z-source inverter (MSC-ZSI) based on the classical ZSI, in which an impedance network consists of symmetric two cells and each cell has two inductors and two capacitors, and one diode In comparison to the other topologies based on switched ZSI, the proposed topology provides higher boost capability and lower voltage stress across switching devices The improved performances of proposed topology are validated by both the simulation and experimental results

Hong-Hee Lee

Papers

Bearing Diagnosis Using Time-Domain Features and Decision Tree

Necessary and Sufficient Stability Condition of Discrete State Delay Systems

Effective power dispatch capability decision method for a wind-battery hybrid power system

Improvement of current performance for grid connected converter under distorted grid condition

Topology of modified switched-capacitor Z-source inverters with improved boost capability