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Induction machine based flywheel energy storage system for isolated microgrid applications

Soomro, A.H. (2021). Induction machine based flywheel energy storage system for isolated microgrid applications. (Unpublished Doctoral thesis, City, University of London)

Abstract

Cleaner production of energy is urgently needed in today’s world due to concerns about global warming and growing population. This need has promoted widespread renewable energy sources and distributed generation, integrated into electricity networks. If renewable sources of energy are added into microgrids powered previously only by fossil-fired engines, their intermittency combined with fluctuation in demand leads to further stability challenges. Energy storage systems offer a solution, which can mitigate the effects of RES intermittency by not only providing a balance between electricity supply and demand but also improving the stability of microgrids. ESS can also reduce the power rating of the generating engine to meet peak demand and enables power production to meet average demand and reducing generation cost. Batteries are nearly always used as the ESS for this application but the subject of this thesis explores an alternative ESS, the flywheel energy storage system (FESS). FESS is one of the earliest forms of energy storage technologies having several benefits of long service time, high power density, low maintenance and insensitivity to environmental conditions. FESS has been an important area of research in recent years. This thesis describes the modelling and analysis of a small-scale energy storage system incorporating FESS with a solar PV system and a diesel engine for use in an islanded system which is supposed to be highly intermittent or non-existent grid infrastructure. In this application, the performance of FESS in the islanded system is assessed and found to be beneficial in comparison to a system either without storage or with alternative ESS technology such as Li-ion batteries. The thesis consists of a description of FESS configured for electrical storage which explains its components and structure; bearing system, flywheel rotor, casings, electrical machine and associated electronic parts. The FESS and its associated control are described in the thesis along with the equations and modelling, carried out in MATLAB/Simulink environment. The simulation of FESS operation is performed over 24hrs which is rarely found in the literature. The operation of FESS for 24hrs provides better assessment of flywheel operation and fuel consumption of DGen. The FESS model is integrated with PV hybrid microgrid system (PVHMS) incorporating dynamic residential load models, diesel generator and PV system. The presented system will be highly useful for the islanded systems or for the areas where there are weak grids or extension of transmission lines is not a feasible option.

Publication Type: Thesis (Doctoral)
Subjects: T Technology > TA Engineering (General). Civil engineering (General)
T Technology > TJ Mechanical engineering and machinery
Departments: School of Science & Technology > Engineering > Mechanical Engineering & Aeronautics
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