Energy characteristics of a fixed-speed flywheel energy storage system with direct grid-connection

Kondoh, Junji; Funamoto, Takuji; Nakanishi, Taisuke; Arai, Ryohei

doi:10.1016/j.energy.2018.09.197

Cited by 19 publications

(9 citation statements)

References 17 publications

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“…This difference in energy is considered to be an overestimation of the loss of approximately 20 W. Another torque meter should be installed between the variable inertia mechanism and the flywheel in the developed prototype to measure the frictional torque in the variable inertia mechanism directly. In this study, the frictional torque and energy consumption in the inertia controller were calculated using Equation (9) to convert the ball screw assembly torque into thrust [13].…”

Section: Discussionmentioning

confidence: 99%

“…A detailed theoretical analysis of the mechanism illustrated in Fig. 2 has been presented in [9,10]. The energy Est stored in the flywheel can be expressed in terms of the kinetic energy Ei (owing to the object rotation) and the potential energy Eg of the flyweights and movable collar (resulting from the difference in vertical positions between l1 , 1 and l2, 2 ), where is gravitational acceleration, as follows:…”

Section: Theoretical Analysismentioning

confidence: 99%

“…It implements the charging and discharging operations by changing J instead of ω. A previously developed prototype machine [9] used an electric winch with a DC motor to change J; however, the efficiency of the DC motor to convert the electrical input to mechanical output was less than 50%, and the net discharge power was not positive. Therefore, in this work, the prototype machine was modified to change J using the rotational inertia torque of the flywheel instead of using an electric winch to make it positive as the net discharge power.…”

Section: Introductionmentioning

confidence: 99%

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Self-Inertia-Varying Fixed-Speed Flywheel Energy Storage System

Yamamoto

Kondoh

2021

IEEJ Journal IA

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Flywheel energy storage systems (FESSs) store kinetic energy corresponding to the rotation of an object as Jω 2 /2, where J is the moment of inertia, and ω is the angular rotation speed. Conventional FESSs implement charging and discharging by varying ω. In contrast, the authors have proposed a fixed-speed FESS that implements charging and discharging by varying not ω but J. However, the net power output in the discharge operation for a fixed-speed FESS was not positive owing to the low efficiency of the mechanism of varying J. This paper reports on the prototype development of a selfinertia-varying fixed-speed FESS that varies J by using the rotational inertia force of the flywheel itself. In the prototype test, actual charging and discharging operations were demonstrated, and a net mechanical power generation was observed during the discharge operation.

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Section: Discussionmentioning

confidence: 99%

Section: Theoretical Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Self-Inertia-Varying Fixed-Speed Flywheel Energy Storage System

Yamamoto

Kondoh

2021

IEEJ Journal IA

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“…The flywheel can be introduced into a wind farm setup to store excess energy during peak production times, to later be released back into the grid at times when there is no wind. In solar systems, FESS is being introduced to prolong the battery storage life that already exists by using the energy stored in the FESS first, so the batteries' workload should be drastically reduced, thereby improving the battery lifespan [34].…”

Section: Application Of Flywheel Energy Storage Systems In Renewable Energy Sourcesmentioning

confidence: 99%

“…This energy is then converted to torque and applied to the rotor, resulting in it spinning rapidly and gaining kinetic energy. This is used when an excess of energy is being produced from an external source, and, therefore, the flywheel stores the energy [34]. When this stored energy is required, the electrical machine acts as a generator, and the kinetic energy stored in the rotor applies a torque.…”

Section: Introductionmentioning

confidence: 99%

Critical Review of Flywheel Energy Storage System

et al. 2021

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This review presents a detailed summary of the latest technologies used in flywheel energy storage systems (FESS). This paper covers the types of technologies and systems employed within FESS, the range of materials used in the production of FESS, and the reasons for the use of these materials. Furthermore, this paper provides an overview of the types of uses of FESS, covering vehicles and the transport industry, grid leveling and power storage for domestic and industrial electricity providers, their use in motorsport, and applications for space, satellites, and spacecraft. Different types of machines for flywheel energy storage systems are also discussed. This serves to analyse which implementations reduce the cost of permanent magnet synchronous machines. As well as this, further investigations need to be carried out to determine the ideal temperature range of operation. Induction machines are currently stoutly designed with lower manufacturing cost, making them unsuitable for high-speed operations. Brushless direct current machines, the Homolar machines, and permanent magnet synchronous machines should also be considered for future research activities to improve their performance in a flywheel energy storage system. An active magnetic bearing can also be used alongside mechanical bearings to reduce the control systems’ complications, thereby making the entire system cost-effective.

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