Integration of Flywheel Energy Storage Systems in Low Voltage Distribution Grids

A Flywheel Energy Storage System (FESS) can rapidly inject or absorb high amounts of active power in order to support the grid, following abrupt changes in the generation or in the demand, with no concern over its lifetime. The work presented in this book studies the grid integration of a high-speed FESS in low voltage distribution grids from several perspectives, including optimal allocation, sizing, modeling, real-time simulation, and Power Hardware-in-the-Loop testing

Experimental Investigation and Evaluation of Future Active Distribution Networks

The UK government’s policy to achieve a 20% renewable energy generation target by 2020, will require significant amounts of SSEG (Small-Scale Embedded Generation) to be connected. In addition to the expected economic and environmental benefits, the anticipated growth in SSEG brings with it numerous challenges for the operation of low voltage and medium voltage distribution networks. At present, there are a number of competing active network management concepts being considered to overcome these challenges and at Durham University a concept defined as the Small Scale Energy Zone (SSEZ) has been proposed and is investigated as part of this research. To further this, a bespoke active low voltage distribution network emulator known as the Experimental SSEZ has been developed by the author. Controllable emulated SSEG, controllable energy storage and controllable emulated load are incorporated into this laboratory. A transformation system has been developed to relate the operation of this system to that of low voltage distribution networks. Centralised and distributed network control systems have been developed for the Experimental SSEZ. These systems were used to evaluate, in conjunction with the relevant literature, the implementation of similar systems on future low voltage distribution networks. Both centralised and distributed control system architectures were found to have their merits. This research should therefore be useful in informing design decisions when developing and implementing active distribution network management systems on LV networks

Battery Energy Storage Systems in the United Kingdom: A Review of Current State-of-the-Art and Future Applications

The number of battery energy storage systems (BESSs) installed in the United Kingdom and worldwide is growing rapidly due to a variety of factors, including technological improvements, reduced costs and the ability to provide various ancillary services. The aim of this paper is to carry out a comprehensive literature review on this technology, its applications in power systems and to identify potential future developments. At first, the main BESSs projects in the UK are presented and classified. The parameters provided for each project include rated power, battery technology and ancillary services provided, if any. In the next section, the most commonly deployed ancillary services are classified and described. At the same time, the nomenclature found in the literature is explained and harmonised. The second part of the paper focuses on future developments and research gaps: ancillary services that currently are not common but that are likely to be deployed more widely in the future will be described, and more general research topics related to the development of BESSs for power system applications will be outlined

Battery Health Estimation for IoT Devices using V-Edge Dynamics

Deployments of battery-powered IoT devices have become ubiquitous, monitoring everything from environmental conditions in smart cities to wildlife movements in remote areas. How to manage the life-cycle of sensors in such large-scale deployments is currently an open issue. Indeed, most deployments let sensors operate until they fail and fix or replace the sensors post-hoc. In this paper, we contribute by developing a new approach for facilitating the life-cycle management of large-scale sensor deployments through online estimation of battery health. Our approach relies on so-called V-edge dynamics which capture and characterize instantaneous voltage drops. Experiments carried out on a dataset of battery discharge measurements demonstrate that our approach is capable of estimating battery health with up to 80% accuracy, depending on the characteristics of the devices and the processing load they undergo. Our method is particularly well-suited for the sensor devices, operating dedicated tasks, that have constant discharge during their operation.Peer reviewe

Holistic Approach To Understanding Battery Degradation

Li-ion cell degradation has a strong impact on electric vehicle performance both directly, through performance reduction, and indirectly through deviating behavior away from initial control system calibration. This necessitates a process for evaluating degradation causes and quantifying corresponding behavioral changes. This paper shows a holistic approach for achieving this, giving both an insight into the causes of cell degradation and emulation of the resultant performance changes through a virtual tools platform which can be used for degradation algorithm development. Additionally, the paper is an overview of the novel methodology developed within the process including testing, data evaluation, modelling and electrical and chemical validation. The process makes use of electrical cycling and electrochemical impedance spectroscopy (EIS) data to evaluate cell stoichiometry and individual impedance features to achieve a much more comprehensive ageing behavioral adaptation than is typically present in Li-ion cell equivalent circuit models. This is achieved while maintaining the versatility and computational efficiency of compact model approaches. The outlined process also gives a resolution of performance changes that allow for conclusions to be drawn on the root causes of ageing only through evaluation of electrical data, which is itself significant. Chemical analysis results are shown to verify the validity of the ageing cause conclusions shown by the process