Solid-state transformer (SST) is an emerging technology integrating with a transformer power electronics converters and control circuitry. This paper comprehensively reviews the SST topologies suitable for different voltage levels and with varied stages, their control operation, and different trends in applications. The paper discusses various SST configurations with their design and characteristics to convert the input to output under unipolar and bipolar operation. A comparison between the topologies, control operation and applications are included. Different control models and schemes are explained. Potential benefits of SST in many applications in terms of controllability and the synergy of AC and DC systems are highlighted to appreciate the importance of SST technologies. This review highlights many factors including existing issues and challenges and provides recommendations for the improvement of future SST configuration and development.

/pdf/state-of-the-art-of-solid-state-transformers-advanced-4j8kucud9h.pdf

State of the art of solid-state transformers: Advanced topologies, implementation issues, recent progress and improvements

Microgrids have emerged as a prospective framework that integrates renewable energy sources, energy storage systems, and loads. They can be addressed as a local distribution system with distributed generators (DGs) and have the potential to improve power quality, reliability, and energy efficiency to their consumers in a grid-connected or islanded mode. However, in order to implement microgrids or distribution systems with DGs, some challenges should be faced, especially concerning protection issues. The possible operating modes and the presence of distributed energy resources may make conventional protection schemes ineffective. Therefore, new protection schemes have been developed in the context of microgrids, including the cases of distribution systems with DGs. Thus, this paper presents a comprehensive survey aiming at studies considering this kind of protection. Emphasis has been given to studies associated with adaptive protection, considered by some researchers as a promising solution for microgrid protection. For this purpose, firstly, a microgrid structure is briefly presented. Afterwards, some challenges related to the protection of these systems are also addressed. Moreover, a brief overview of adaptive protection is provided, and then the newly developed schemes found in the technical literature are described. It is worth mentioning that a bibliometric analysis is also presented in this paper, highlighting a substantial growth in publications concerning adaptive protection. Nevertheless, it can be observed that more effort is still needed to obtain a complete solution for the protection of microgrids and distribution systems with DGs. Further attention to matters such as communication failures, cyberattacks, and the presence of energy storage systems should emerge in the next few years.

A survey on adaptive protection of microgrids and distribution systems with distributed generators

AC microgrid protection – A review: Current and future prospective

The article described an open-source toolbox for machine vision called Machine Vision Toolbox (MVT) MVT includes more than 60 functions including image file reading and writing, acquisition, display, filtering, blob, point and line feature extraction, mathematical morphology, homographies, visual Jacobians, camera calibration, and color space conversion MVT can be used for research into machine vision but is also versatile enough to be usable for real-time work and even control MVT, combined with MATLAB and a model workstation computer, is a useful and convenient environment for the investigation of machine vision algorithms The article illustrated the use of a subset of toolbox functions for some typical problems and described MVT operations including the simulation of a complete image-based visual servo system

The Machine Vision Toolbox : A MATLAB Toolbox for vision and vision-based control

The increase in the penetration of renewable energy sources (RES) has reduced the effective inertia of the power system dominated by synchronous machines. The reduction in inertia has paved the way to the development of inertia emulation techniques, which complements the increased penetration of RES. The synchronverter technology is one among the virtual inertia emulation techniques which resembles close to the synchronous machine. The advancements in control and adaptations of synchronverter for various applications demand a comprehensive yet critical review. Thus, the main objective of this paper is to present a critical review of synchronverter technology which could increase the inertial response of RES. A critical analysis of modifications made to original synchronverter and the stability assessment techniques is presented. The effect of parameter variation on stability and dynamic performance is brought out as a decision matrix by analysing the movement of eigenvalues presented in various works. Towards the end, a synoptic overview is presented to depict the research trend and emphasize the domain which requires further attention. Furthermore, a brief discussion of the research gaps perceived during the phase of review is presented to leverage future research in the field.

/pdf/synchronverter-a-comprehensive-review-of-modifications-47w8hih9z3.pdf

Synchronverter: A Comprehensive Review of Modifications, Stability Assessment, Applications and Future Perspectives

This paper presents an idea to share the battery condition monitoring parameters among the stakeholders like manufacturer, market dealers, users etc. by using latest Internet of Things (IoT) technology. Upon accessing such parameters, corrective actions can be taken to improve the battery life. By placing sensors on the battery, which can send the battery parameter data over internet to cloud database. This database can be accessed by manufacturer, dealers and users to monitor the health condition of battery. This will help to enhance the efficient use of battery and improve the life. Also, it can track the number of batteries in use with usage profile. The hardware prototype of the proposed system has been developed and tested with a lead acid SMF battery. The Mean Square Error (MSE) of the measured quantities are with in acceptable limits.

Battery Condition Prognostic System using IoT in Smart Microgrids

The existing power grid is experiencing sustaining energy shortage Distributed generation (DG) including wind energy, solar energy can be a solution for the energy shortage in the existing power grid Distributed generation is the generation of power using small sized generators that produces electric power at low voltage levels and is connected to the distribution network directly near the load centers The distributed generations have some negative impacts in the existing power grid in the protection level The DG sources like wind energy, solar energy etc are dynamic in nature which results in the variation of source impedance In the presence of distributed generation the fault current characteristics are also changing The existing relay parameters are not able to identify these changes, which results in malfunction of relays The solution strategy adopted for the malfunction of relays is adaptive relaying Adaptive relaying means the relay has to adapt to the changing environment and the decision making capability is to be added with existing relays The impact of increment of DG penetration in protection in IEEE 5 bus system and a real system which is a Kerala grid system is studied and multiagent based adaptive relaying is proposed as a solution strategy

Multiagent based adaptive relaying for distribution network with distributed generation

Nanogrids are the building blocks of a microgrid which is powering a single building. Low voltage DC distribution system within building structures is called a LVDC nanogrid. DC electronic loads like LED Lights, BLDC fans, PC, battery system and renewable sources can be connected to the nanogrid. LVDC nanogrid is a low power DC distribution system suitable for residential applications with an efficient power and control architecture. The Nanogrid power architecture consists of subsystems such as the Nanogrid system controller, Nanogrid power Switch/socket, Battery Management System, Solar PV Converter and backup AC/DC converters. The average load demand in the nanogrid is provided by the local renewable energy resources like solar PV. A battery management system ensures uninterruptible power supply to the high priority loads. The objective of the work is to investigate the power and control architecture to evolve the specifications, to implement Low Voltage Direct Current (LVDC) Nanogrid for residential applications. Protocol for LVDC communication is based on CANopen standard (EN 50325-4). Control Strategies for optimal power management in Nanogrid is highlighted in this work.

Low voltage direct current(LVDC) nanogrid for home application

Lack of inertia in inverter dominated utility grids and smart microgrids is a serious issue that needs to be tackled and to enable larger integration of renewable energy sources, which are usually interfaced to the grid using power electronic converters. Recently, it has been proposed to embed the dynamics of conventional synchronous machines into power electronic converters to operate them as virtual synchronous machines or synchronverters. Since, the power electronic converters do not have rotational inertia, the electrical energy storage provides the virtual inertia to the virtual synchronous machine. Although a virtual synchronous machine is physically a power electronic converter, its operation is governed by the mathematical equations of a synchronous machine. Virtual synchronous machine based inverters may play a major role in future microgrids since it can impart the inertial response to weak grids during sudden frequency transients. The inverters in a microgrid should be capable of operating in autonomous mode in addition to the grid connected mode. In this paper, the performance of a virtual synchronous machine based inverter operation in autonomous mode is analyzed. The simulation is done using MATLAB/Simulink and the simulation results are validated with the hardware experiments using OPAL-RT real time simulator.

S. Ashok

Papers

Battery Condition Prognostic System using IoT in Smart Microgrids

Multiagent based adaptive relaying for distribution network with distributed generation

Low voltage direct current(LVDC) nanogrid for home application

Performance of virtual synchronous machine in autonomous mode of operation

Small Signal Stability Analysis of Grid Connected Renewable Energy Resources with the Effect of Uncertain Wind Power Penetration