Flywheel Based Energy Storage Systems Research Articles

Assessment of photovoltaic powered flywheel energy storage system for power generation and conditioning

Energy storage and power conditioning are the two major issues related to renewable energy-based power generation and utilisation. This work discusses an energy storage option for a short-term power requirement, which also acts as a power conditioner. The flywheel, an old invention, is included in the electrical power generation arrangement to achieve energy storage and power conditioning requirements. A Photovoltaic solar system is used as a primary source from which the required DC voltage is obtained through an SPWM-based DC-DC converter. This power is fed to an arrangement consisting of a BLDC machine as prime mover, which drives a mass of flywheel. An alternator connected with the motor and flywheel to supply a 1000 W load. The flywheel is designed to take care of the dynamic stability assisted by a suitably designed controller unit and supporting power supply units t ensure the system's reliability. Hence a conditioned and reliable power supply is provided to the load. This research aims to decide on the dimensions and material of the flywheel to be used, which was achieved using ANSYS. Two different materials were selected, and stress analysis was done to ensure their suitability as an energy storage medium in the power generation system. Similarly, the converters and controllers were simulated using MATLAB to fit them to the renewable power generation scheme based on which a working model is fabricated, and tested through proper commissioning, to get the aimed objectives. The outcome of simulation and experimentation were compared, and suitable illustrations were given to prove the successful implementation of a flywheel-based energy storage system.

The Landscape of Flywheel Energy Technology in the Philippines

A 20-year Philippine energy roadmap was released by the Department of Energy that covers national renewable energy program, and a framework of energy storage systems. The energy plan entails increasing the share of renewable energy sources in the power mix and the use of energy storage systems to further increase efficiency and effectiveness of electric power delivery in the country. A flywheel-based energy storage system is emerging in the country and in this paper, the landscape of flywheel energy technology is discussed which includes the components of the flywheel system, other energy storage systems, development, and innovations in the local energy sector, as well as the opportunities and impact of flywheel energy technology in the Philippine economy. Moreover, flywheel technology implementation poses challenges in terms of research and development towards reaching its full potential and growth in fabrication, manufacturability, deployment, quality assurance, data analytics, and systems integration.

Inertia Emulation Uncorrelated With Electromechanical Dynamics to Improve Frequency Transients Using Center of Inertia (COI) Frequency Signal

This paper proposes an inertia emulation method that uses the frequency of the center of inertia (COI) as the feedback signal, aiming to slow the frequency change rate and raise the frequency nadir during frequency-dropping events. An approximated model depicting the COI frequency dynamics is first introduced, which shows the COI frequency signal has low observabilities of electromechanical modes. Thus, this feature enables the proposed inertia emulation to react quickly to steep frequency changes without suffering any adverse impacts caused by electromechanical dynamics, such as excessively saturating the controlled objects. Moreover, the electromechanical dynamics associated with small-signal stability properties will not be interrupted by the proposed inertia emulation. In addition, a simple yet effective computing procedure is proposed to configure the critical parameters, as the inertia emulation is implemented with multiple flywheel-based energy storage systems. Simulation results obtained based on two large interconnected systems verify the effectiveness of the proposed inertia emulation in terms of improving the frequency transients as well as its limited correlation with the electromechanical dynamics of the system. The signal transmission latency's impacts on the proposed inertia emulation are also investigated and discussed.

A Lab-scale Flywheel Energy Storage System: Control Strategy and Domestic Applications

Flywheel is a promising energy storage system for domestic application, uninterruptible power supply, traction applications, electric vehicle charging stations, and even for smart grids. In fact, recent developments in materials, electrical machines, power electronics, magnetic bearings, and microprocessors offer the possibility to consider flywheels as a competitive option for electric energy storage, which can be of great interest for domestic applications in the near future. In this paper, a grid-tied flywheel-based energy storage system (FESS) for domestic application is investigated with special focus on the associated power electronics control and energy management. In particular, the overall PMSM-based flywheel configuration is reviewed and a controlling strategy was experimentally implemented using DS1104 controller board from dSPACE. Two case studies were considered for power peak shaving and power backup at domestic level. A lab-scale prototype was built to validate the proposal. The achieved results are presented and discussed to demonstrate the possibilities offered by such an energy storage system for domestic application.

Technical Aspects of Critical Components for High-Temperature Superconductor Bearings-Based Flywheel Energy Storage System

Flywheel-based energy storage systems are gaining prominence in present-day energy-deficit situation. For energy storage system, the bearings and motor cum generator, for charging and discharging energy to and from the flywheel, form the vital components which have to be given due consideration. The low coefficient of friction of high-temperature superconductor bearings used in flywheel-based energy storage systems decides the energy loss factor. Yttrium Barium copper oxide (YBCO) which is one of the popular high-temperature superconductors is widely being used in high-temperature superconductor bearings. The planar type of bearings can be materialised by building the stator of the bearing with YBCO bulk high-temperature superconductor discs mounted in a circular array and rotor part can be realised by Nd–Fe–B permanent magnet ring which is to be embedded with the flywheel. The levitation force is proportional to the mean magnetization of high-temperature superconductor and the horizontal gradient of the vertical component of the magnetic field density in the superconductor. The magnetization is proportional to the product of critical current density and the grain diameter of the bulk superconductor. The high-temperature superconductor bearings outweigh the magnetic bearings because their passive nature, by virtue, does not require any external active stability balancing devices. The paper discusses of development, fabrication and load testing of prototype planar type of high-temperature superconductor bearings. For charging and discharging energy to and from the flywheel energy storage system, Halbach array-type motor cum generator is a promising candidate. The motor, with an outside rotor design, is a dipole Halbach array, establishing a uniform flux within the stator area. A uniform flux is needed for operating the motor on a superconductor bearing, where slight movement of the stator inside the air gap is inevitable. The salient construction features of the prototype Halbach array motor generator will be discussed.

Theoretical and experimental analysis of the lubricating system of a high speed multiplier

Flywheel-based energy storage systems are used for energy storage in form of kinetic energy using a flywheel rotating at high speed. In order to achieve this high rotating speed a high speed multiplier could be used in order to increase the rotation speed of a conventional motor. This article presents a theoretical and experimental analysis of the lubricating system of a high speed multiplier used in a flywheel-based energy storage system. The necessary oil flow is theoretically computed using analytical formulas. The oil is used for lubricating the gears, the roller bearings and the sliding bearings. An experimental test rig is used to measure the oil flow. Finally the two results are compared.

Design and Analysis of a Unique Energy Storage Flywheel System—An Integrated Flywheel, Motor/Generator, and Magnetic Bearing Configuration

Energy storage is becoming increasingly important with the rising need to accommodate the energy needs of a greater population. Energy storage is especially important with intermittent sources such as solar and wind. Flywheel energy storage systems store kinetic energy by constantly spinning a compact rotor in a low-friction environment. When short-term back-up power is required as a result of utility power loss or fluctuations, the rotor’s inertia allows it to continue spinning and the resulting kinetic energy is converted to electricity. Unlike fossil-fuel power plants and batteries, the flywheel based energy storage systems do not emit any harmful byproducts during their operation and have attracted interest recently. A typical flywheel system is comprised of an energy storage rotor, a motor-generator system, bearings, power electronics, controls, and a containment housing. Conventional outer flywheel designs have a large diameter energy storage rotor attached to a smaller diameter section which is used as a motor/generator. The cost to build and maintain such a system can be substantial. This paper presents a unique concept design for a 1 kW-h inside-out integrated flywheel energy storage system. The flywheel operates at a nominal speed of 40,000 rpm. This design can potentially scale up for higher energy storage capacity. It uses a single composite rotor to perform the functions of energy storage. The flywheel design incorporates a five-axis active magnetic bearing system. The flywheel is also encased in a double layered housing to ensure safe operation. Insulated-gate bipolar transistor (IBGT) based power electronics are adopted as well. The design targets cost savings from reduced material and manufacturing costs. This paper focuses on the rotor design, the active magnetic bearing design, the associated rotordynamics, and a preliminary closed-loop controller.

Control and simulation of a flywheel energy storage for a wind diesel power system

Abstract Wind diesel power systems (WDPSs) are isolated microgrids which combine wind diesel generators with wind turbine generators. If the WDPS includes a short-term energy storage system (ESS) both the logistic and the dynamic operation are improved. Flywheel based energy storage systems (FESSs) have characteristics that make them very appropriate to be used as short-term ESS in WDPS, so that a FESS, is added to the WDPS. The FESS main components: electrical machine, flywheel, grid converter and electrical machine converter are described. As the main aim of the FESS in the present article is power quality improvement, a robust low cost low-speed FESS (LS-FESS) is selected. The LS-FESS which includes an asynchronous machine (ASM) and a steel flywheel is sized for a particular WDPS. The FESS power converters and ASM can be controlled as if they were a servo but, in order to attain more robustness, it is better to control the ASM converter to maintain a constant DC-voltage in the DC-link and to control the grid converter to exchange the necessary power references with the isolated grid. Finally, in order to verify the proposed low speed FESS, it is simulated along with the WDPS. Simulation results with graphs for the isolated power system frequency and voltage, active powers generated/consumed by the WDPS elements, the FESS-ASM direct and quadrature currents and FESS-flywheel speed are presented for load and wind speed steps. The simulations show a power quality improvement of the isolated microgrid due to the use of the FESS.

Flywheel charging module for energy storage used in electromagnetic aircraft launch system

Optimal energy systems is currently designing and manufacturing flywheel based energy storage systems that are being used to provide pulses of energy for charging high voltage capacitors in a mobile military system. These systems receive their energy from low voltage vehicle bus power (<480 VDC) and provide output power at over 10,000 VDC without the need for DC-DC voltage conversion electronics. This energy conversion is accomplished through the use of OES patented ultra high-speed flywheel power module (FPoM) technology. In this paper, adaptation of the OES FPoM technology to energy storage for electromagnetic aircraft launch system (EMALS) applications is described. Physical system design parameters are summarized for the FPoM. Transient PSPICE electrical and MSC/Nastran FEA thermal analyses characterize operation and response in a conceptual EMALS energy storage environment.