Flywheel Energy Storage Systems for Wind Turbine Grid Frequency Stability: A Review

Author(s):  
Ilker Durukan ◽  
Stephen Ekwaro-Osire ◽  
Stephen B. Bayne

Most recent grid codes require wind turbines to contribute to the recovery of frequency drops in the grid. More of the recently build wind turbines use variable speed generators. Unlike fixed speed generators, these generators do not naturally contribute to the recovery of the frequency drop since the rotor rpm is decoupled from the grid frequency. This decoupling is achieved by controller and power conditioning units. The studies reviewed in this paper focused on the design of such a controller so that the wind turbine could react to frequency drops. Another approach to responding to frequency drops is to connect an energy storage system to the DC bus of variable speed generator. Flywheels have been used as energy storage systems to fill energy gaps in several applications and can be used for frequency recovery application for wind turbines as well. The objective of this study was to demonstrate the improvement of frequency stability of wind turbines connected to electrical grids in the presence of flywheel energy storage systems (FESS). Studies reviewed show that FESS can enhance the power quality and frequency stability of wind turbines connected to an electrical grid.

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2159
Author(s):  
A.G. Olabi ◽  
Tabbi Wilberforce ◽  
Mohammad Ali Abdelkareem ◽  
Mohamad Ramadan

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.


Author(s):  
Arunvel Kailasan ◽  
Timothy Dimond ◽  
Paul Allaire ◽  
David Sheffler

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-hr inside-out integrated flywheel energy storage system. The flywheel operates at a nominal speed of 40,000 rpm. This design can potentially scaled up for higher energy storage capacity. It uses a single composite rotor to perform the functions of energy storage. The flywheel design incoporates a 5-axis active magnetic bearing system. The flywheel is also encased in a double layered housing to ensure safe operation. IGBT 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.


2017 ◽  
Vol 68 (11) ◽  
pp. 2641-2645
Author(s):  
Alexandru Ciocan ◽  
Ovidiu Mihai Balan ◽  
Mihaela Ramona Buga ◽  
Tudor Prisecaru ◽  
Mohand Tazerout

The current paper presents an energy storage system that stores the excessive energy, provided by a hybrid system of renewable energy sources, in the form of compressed air and thermal heat. Using energy storage systems together with renewable energy sources represents a major challenge that could ensure the transition to a viable economic future and a decarbonized economy. Thermodynamic calculations are conducted to investigate the performance of such systems by using Matlab simulation tools. The results indicate the values of primary and global efficiencies for various operating scenarios for the energy storage systems which use compressed air as medium storage, and shows that these could be very effective systems, proving the possibility to supply to the final user three types of energy: electricity, heat and cold function of his needs.


2019 ◽  
Vol 11 (1) ◽  
pp. 186 ◽  
Author(s):  
Byuk-Keun Jo ◽  
Seungmin Jung ◽  
Gilsoo Jang

Energy storage systems are crucial in dealing with challenges from the high-level penetration of renewable energy, which has inherently intermittent characteristics. For this reason, various incentive schemes improving the economic profitability of energy storage systems are underway in many countries with an aim to expand the participation rate. The electricity charge discount program, which was introduced in 2015 in Korea, is one of the policies meant to support the economic feasibility of demand-side energy storage systems. This paper quantitatively evaluated the impact of the electricity charge discount program on the economic feasibility of behind-the-meter energy storage systems. In this work, we first summarized how electricity customers can benefit from behind-the-meter energy storage systems. In addition, we represented details of the structure that make up the electricity charge discount program, i.e., how the electricity charge is discounted through the discount scheme. An optimization problem that establishes a charge and discharge schedule of an energy storage system to minimize each consumer’s electricity expenditure was defined and formulated as well. The case study results indicated that the electricity charge discount program has improved the profitability of behind-the-meter energy storage systems, and this improved profitability led to investment in behind-the-meter energy storage systems in Korea. As a result of the electricity charge discount program, Korea’s domestic demand side energy storage system market size, which was only 27 billion dollars in 2015 in Korea, has grown to 825 billion dollars in 2018.


Author(s):  
Xiao Ping Wu ◽  
Masataka Mochizuki ◽  
Koichi Mashiko ◽  
Thang Nguyen ◽  
Tien Nguyen ◽  
...  

In this paper, design and economic analysis for applying a novel type of heat pipe into cold energy storage systems have been proposed and discussed. The heat pipe cold energy storage systems can be designed into several types that are ice storage, cold water storage and pre-cool heat exchanger. Those systems can be used for co-operating with conventional chiller system for cooling data centers. The heat load used for discussing in this paper is 8800 kW which represents a large scale data center. The methodology addressed in this paper can be also converted into the middle and small sizes of the data centers. This type of storage system will help to downsize the chiller and decrease its running time that would be able to save significant electricity cost and decrease green house gas emissions from the electricity generation. The proposed systems can be easily connected into the existing conventional systems without major design changes. The analysis in this paper is using Air Freezing Index AFI >= 400 °C-days/year for sizing the heat pipe modules. For the locations where AFI has different value the storage size will be varied accordingly. The paper also addressed a result that an optimum size of cold energy storage system that should be designed at a level to handle 60% of total yearly heat load of a data center.


Author(s):  
Sammy Houssainy ◽  
Reza Baghaei Lakeh ◽  
H. Pirouz Kavehpour

Human activity is overloading our atmosphere with carbon dioxide and other global warming emissions. These emissions trap heat, increase the planet’s temperature, and create significant health, environmental, and climate issues. Electricity production accounts for more than one-third of U.S. global warming emissions, with the majority generated by coal-fired power plants. These plants produce approximately 25 percent of total U.S. global warming emissions. In contrast, most renewable energy sources produce little to no global warming emissions. Unfortunately, generated electricity from renewable sources rarely provides immediate response to electrical demands, as the sources of generation do not deliver a regular supply easily adjustable to consumption needs. This has led to the emergence of storage as a crucial element in the management of energy, allowing energy to be released into the grid during peak hours and meet electrical demands. Compressed air energy storage can potentially allow renewable energy sources to meet electricity demands as reliably as coal-fired power plants. Most compressed air energy storage systems run at very high pressures, which possess inherent problems such as equipment failure, high cost, and inefficiency. This research aims to illustrate the potential of compressed air energy storage systems by illustrating two different discharge configurations and outlining key variables, which have a major impact on the performance of the storage system. Storage efficiency is a key factor to making renewable sources an independent form of sustainable energy. In this paper, a comprehensive thermodynamic analysis of a compressed air energy storage system is presented. Specifically, a detailed study of the first law of thermodynamics of the entire system is presented followed by a thorough analysis of the second law of thermodynamics of the complete system. Details of both discharge and charge cycles of the storage system are presented. The first and second law based efficiencies of the system are also presented along with parametric studies, which demonstrates the effects of various thermodynamic cycle variables on the total round-trip efficiency of compressed air energy storage systems.


Energies ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3498 ◽  
Author(s):  
Tiezhou Wu ◽  
Wenshan Yu ◽  
Lujun Wang ◽  
Linxin Guo ◽  
Zhiquan Tang

Traditional hierarchical control of the microgrid does not consider the energy storage status of a distributed hybrid energy storage system. This leads to the inconsistency of the remaining capacity of the energy storage system in the process of system operation, which is not conducive to the safe and stable operation of the system. In this paper, an improved hierarchical control strategy is proposed: the first allocation layer completes the allocation between the distribution energy storage systems considering the state of hybrid energy storage systems, and the second allocation layer realizes the allocation within the hybrid energy storage systems based on variable time constant low-pass filtering. Considering the extreme conditions of energy storage systems, the transfer current is introduced in the second allocation process. The SOC (stage of charge) of the supercapacitor is between 40% and 60%, which ensures that the supercapacitor has enough margin to respond to the power demand. An example of a 300 MW photovoltaic microgrid system in a certain area is analyzed. Compared with the traditional hierarchical control, the proposed control strategy can reduce the SOC change of a hybrid energy storage system by 9% under the same conditions, and make the supercapacitor active after power stabilization, which is helpful to the stable operation of the microgrid.


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