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 a novel control strategy for smooth transition between stand-alone and grid-connected modes of distributed generation (DG). The proposed control scheme is designed in stationary (α-β) reference frame consisted of outer grid current control loop using a proportional resonant (PR) controller and the inner load voltage control loop developed with a repetitive controller (RC). The proposed control strategy is able to produce a sinusoidal load voltage in stand-alone mode and a sinusoidal grid current in grid-connected operation of the DG despite the presence of nonlinear local load. One unified control scheme is developed for both stand-alone and grid-connected operations so that the DG does not need to change control scheme and voltage or current spikes can be effectively prevented during transition period. Since the control system is developed in the α-β reference frame, coordinate transformations are not required, which can significantly reduce the complexity and improve the accuracy of the DG control system. The feasibility of the proposed method is validated through selected simulated and experimental results.

https://ieeexplore.ieee.org/iel7/7152671/7167754/07167944.pdf

A novel control strategy for smooth transition between stand-alone and grid-connected operations of distributed generation

This paper presents a study on direct torque control method (DTC) using matrix converter fed induction motor. The advantages of matrix converters are combined with the advantages of the DTC technique: under the constraint of unity input power factor, the required voltage vectors are generated to implement the conventional DTC method of induction motor. However, since the first idea about DTC method using MC fed induction motor was suggested by the current researches just focus on some simulation results and a little un-explicit experimental result is carried out. This paper describes the operation of induction motor under the DTC method in steady-state and transient conditions by the experimental results, the discussion about the trend of DTC method using MC is also carried out. Furthermore, the entire system of matrix converter configuration using 7.5 kW IGBT modules (FR35R12KE3V1) is explained in detail.

Implementation of direct torque control method using matrix converter fed induction motor

The fast grow of photovoltaic (PV) systems is making more green energy but also creating challenges on how to communicate in a large system with a lot of distribution solar sources when they all connect to the national grid. The communication becomes the important part for data acquisition in order to control the whole system stable and efficiency. To deal with this challenge, this paper presents a solution based on Zigbee and Ethernet communication standard. Zigbee standard was created to be a specification of a high level wireless communication protocol which is not only secure, reliable, simple but also low cost and low power. Zigbee is especially suitable for a large network with thousands of devices. So with Zigbee, we can create a communication network for hundreds to thousands of mini solar sources in a large scale of photovoltaic system. Ethernet is a high speed wired communication technology that is used widely in industrial and automatic applications. Together Zigbee and Ethernet bring to us a real-time communication solution for the system. In the experiment prototype of this paper, we use the CC2530ZNP-Mini Kit to create a simple network includes one coordinate and one end device for the first step. The end device was configured to get current and voltage values from a 3-phase gird-connected solar inverter 800Wpk and then send the values to the coordinate. After the coordinate received data, it would send them to an Ethernet controller board. This board was controlled by the STM32F407 chip which is based on the high-performance ARM®Cortex™-M4 32-bit RISC core operating at a frequency of up to 168 MHz. To display the data through Ethernet, we embedded a web server on the chip. By this way, the data was easy to visualize and supervised by using any web browser.

Real-time communication network solution based on Zigbee and Ethernet for photovoltaic systems

This paper proposes a novel cooperative control strategy for voltage restoration and power management in DC microgrids based on the DC bus signaling (DBS) method. In the conventional DBS method, the operation mode is determined according to the voltage deviation. Thus, it is difficult to achieve voltage restoration. To overcome this problem, the conventional DBS method is modified by applying the total power of dispatchable units (DUs) to identify the operation mode instead of the voltage deviation. As a result, the average output voltage of the DUs is restored to its nominal value in all of the operation modes without difficulty. In addition, accurate power sharing is achieved regardless of the line impedance or load change by regulating the voltage magnitude using a simple PI controller. Furthermore, the control performance is theoretically analyzed using a small signal analysis to evaluate the stability of system. The proposed method is validated with results from a lab scale experiment.

Cooperative control strategy for voltage restoration and power allocation in DC microgrids

An H/sub 2/ servo controller is proposed for networked control systems. The network-induced delay is assumed to be time-varying and vary in the known range. The proposed controller guarantees stability and H/sub 2/ performance for all time-varying delay in the known range. The proposed controller is verified using a simple networked motor control system.

http://infolab.ulsan.ac.kr/research/acc(2005).pdf

Hong-Hee Lee

Papers

A novel control strategy for smooth transition between stand-alone and grid-connected operations of distributed generation

Implementation of direct torque control method using matrix converter fed induction motor

Real-time communication network solution based on Zigbee and Ethernet for photovoltaic systems

Cooperative control strategy for voltage restoration and power allocation in DC microgrids

H/sub 2/ networked servo control systems with time-varying delays