Flywheel Energy Storage System Research Articles

Hybrid PV System with High Speed Flywheel Energy Storage for Remote Residential Loads

Due to low system inertia in microgrids, frequencies may vary rapidly from the nominal value, leading to the complete blackout of the system unless there is an adequate spinning reserve available for balancing the supply with the demand load. This issue of instability in microgrids under islanded operation has attracted particular attention recently. A diesel generator is considered to be an ideal spinning reserve to provide back-up power to the load along with the renewable energy source in islanded system. However, the high maintenance cost and CO2 emissions of diesel generator are detrimental factors which have inspired searches for more cost effective and cleaner technologies. The integration of an energy storage system (ESS) in islanded system along with generator not only reduces generator maintenance costs but also reduces the CO2 emissions by limiting its operating hours. This paper proposes an islanded PV hybrid microgrid system (PVHMS) utilizing flywheel energy storage systems (FESS) as an alternative to battery technology to support the PV system and meet the peak demand of a small residential town with 100 dwellings. The diesel generator is used in the islanded system as a spinning reserve to maintain the stability of the islanded system when the PV system and flywheel storage cannot meet the load demand. Results of analysis of such a system demonstrate that flywheel energy storage technology of appropriate size offers a viable solution to support the operation of the standalone PV system. Furthermore, the reduction in CO2 emissions and fuel consumption has been quantified as compared with the case with flywheel energy storage systems which means the diesel generator but always be operating.

Critical Review of Flywheel Energy Storage System

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.

Imperialist competitive algorithm optimized cascade controller for load frequency control of multi-microgrid system

ABSTRACT Control of multi-energy source-based microgrid is a complex task due to the presence of unpredictable renewable energy sources (RES). This paper proposes a cascade structure of proportional derivative with (1+ PI) controller (C-PDF(1+ PI)) for load frequency control of an AC multi Micro-grid (MG). The MG contains a thermal power unit, Diesel Engine Generator (DEG), Micro Turbine (MT), Fuel Cell (FC), and uncontrolled solar and wind sources. Diverse storage device units like Battery Energy Storage System (BESS), Fly Wheel Energy Storage System (FESS), and Electric Vehicles (EV) are also included in the studied MG system. The proposed C-PDF(1+ PI) controller consists of a first stage Proportional Derivative controller with filter (PDF) and one plus proportional-integral (PI) controller in the second stage. The Imperialist Competitive Algorithm (ICA) is applied to optimize the controller parameters. To confer superiority of the C-PDF(1+ PI) controller, its responses are related with PI, PID, and PIDF controllers. It is observed that the ITAE improvement in percentage with the proposed approach is 70.64%, 53.23%, and 47.10% compared to PI, PID, and PIDF controller while considering the simultaneous variations in load, solar, and wind powers. To justify the efficacy of the ICA technique, it is compared with other well-established techniques like the Genetic algorithm (GA) and the Cuckoo Search algorithm (CSA). It is observed that for the identical system and C-PDF(1+ PI) controller, the ITAE value improvement in percentage by ICA compared to GA and CSA are 31.94% and 15.93%, respectively, while considering all the three uncertainty like changes in load condition, change in solar power irradiation and changes in wind power conditions. Finally, it is conferred that the proposed ICA optimized C-PDF(1+ PI) controller significantly improves microgrid dynamic performance under various operational conditions.

A novel capacity configuration method of flywheel energy storage system in electric vehicles fast charging station

This paper proposes a capacity configuration method of the flywheel energy storage system (FESS) in fast charging station (FCS). Firstly, the load current compensation and speed feedback control (LCC-SFC) strategy adopted by permanent magnet synchronous motor (PMSM) is introduced and the curve of “source-storage-load power characteristics” is obtained. Then, the capacity configuration of PMSM-FESS that satisfies the load energy and power requirements in the initial stage of fast charging is studied, which includes the rotational inertia of flywheel rotor and the mechanical angular velocity. Also, the power allocation of flywheel-side converter is analyzed. Finally, the system simulation model is built under Matlab/Simulink, the simulation value of the slope of gird power is approximate to its theoretical expected value. And the effectiveness of the capacity configuration method is verified. The results are helpful to the practical application of PMSM-FESS in the field of EV fast charging station.

Influence of Rotor Eccentricity Types on the Operating Performance for a 100 KW HTS Maglev Flywheel System

Due to the low radial restoring force stiffness of the radial high-T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> superconducting maglev bearing (SMB) in high-T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> superconducting flywheel energy storage system (SFESS), it is difficult to provide enough radial constraint when the rotation speed is high. The dynamic simulation analysis of the SFESS rotor was carried out based on the testing and analysis of the static force results of the SMB. On the one hand, according to the results of dynamic analysis, the flywheel rotor would be eccentric when it is subjected to an unbalanced force. On the other hand, because of the special operation mechanism of the SFESS, the flywheel rotor would be prone to be eccentric before rotation. These two types of eccentricity will affect the operating performance of SFESS. Therefore, the research on the working condition of SFESS under eccentric state not only can predict the operating performance of SFESS in extreme cases in advance but also judge whether the SFESS has eccentric operation by comparing the real-time speed value with the preset value, which is of great significance to the further research of the SFESS.

Solar Photovoltaic Interfaced Quasi Impedance Source Network Based Static Compensator for Voltage and Frequency Control in the Wind Energy System

In this paper, the purpose of improving the power quality of the standalone wind conversion system (WECS) is to utilize a quasi-impedance (qZ) static compensator (STATCOM) integrated solar photovoltaic (SPV) source network. The standalone WECS has utilized the flywheel energy storage system (FESS) and the self-excited induction generator (SEIG). The SPV power generation network integrates with the STATCOM DC-Link to compensate for the voltage and frequency fluctuations over a longer time. The SEIG terminal voltage and STATCOM DC-link voltage are regulated using an enhanced second-order generalized integrator (ESOGI) with a fuzzy logic controller (FLC). The coordination logic is proposed in order to handle the various scenarios and make the device energy efficient. The unit is built for optimal usage of the electrical energy generated from renewable sources by utilizing physical energy storage systems such as flywheel and battery. In both batteries and flywheels, excess power from the SPV and wind turbines is collected. To verify the performance of the SPV supported STATCOM, the simulation and experimental studies are performed under specific load conditions. This paper describes an optimal way to produce and utilize green power with better energy efficiency. With various current conditions, the typical level of harmonic distortion of the source current is about 1.4% lower than that specified by IEEE Std. 519–2014 for the tolerable 5% level.

Modified Salp Swarm Algorithm-Optimized Fractional-Order Adaptive Fuzzy PID Controller for Frequency Regulation of Hybrid Power System with Electric Vehicle

A considerable no. of intermittent renewable sources such as PV generation and wind energy when integrated to the conventional grid technology causes serious issues in the power systems like frequency instability. So a more balancing controller is desired for a stable and reliable operation of the power system. Bidirectional power control of the EV aggregator is making itself a wise choice for distributed energy storage to scale down the frequency and power fluctuation. In this work, an intelligent load frequency controller using a fractional-order adaptive fuzzy PID controller with filter (FOAFPIDF) for hybrid power system with electric vehicle (EV) based on modified salp swarm algorithm (MSSA) technique is proposed. The effectiveness of MSSA technique is compared with original salp swarm algorithm as well as moth flame optimization , grey wolf optimization , particle swarm optimization and sine cosine algorithm techniques for benchmark test functions using statistical analysis. The effectiveness of the suggested load frequency control strategy by the use of electric vehicle as well as with other energy storing elements such as the superconducting magnetic energy storage component, flywheel energy storage system and ultra-capacitor along with their inherent rate constraint nonlinearity is validated by numerical simulations conducted on the studied test system. It is demonstrated that the proposed controller provides a better control action to suppress the frequency fluctuations as compared to PID controller. The robustness of the controller is also investigated against variation of system parameters and random load changes.

Experimental Characterization of Low-Speed Passive Discharge Losses of a Flywheel Energy Storage System

Flywheel energy storage has a wide range of applications in energy grids and transportation. The adoption of high-performance components has made this technology a viable alternative for substituting or complementing other storage devices. Flywheel energy storage systems are subject to passive discharge attributed primarily to electrical machine losses, bearing rolling friction, and aerodynamic drag of the flywheel rotor. In the present study, measurements are presented for complete discharge experiments using a flywheel system featuring a vacuum enclosure. Best-fit equations were applied to the test data and compared to analytical models. Analysis of the best-fit equations indicates that they may serve as empirical models for approximating passive discharge under given conditions. Bearing losses, which varied linearly with velocity but were otherwise unaffected throughout the experiments, were larger than aerodynamic drag at low air pressures and low velocities. Aerodynamic drag became significant as velocity exceeded approximately 3400 rpm. The electrical machine was found to be the most significant source of passive discharge at all velocities and pressures. Based on these findings, it is recommended to maintain a low-pressure environment in the flywheel enclosure and to decouple the electrical machine from the rotor whenever possible to eliminate associated losses.

A comparative study of the speed control of an IM–based flywheel energy storage system using PI–DTC and RFOC strategies

Abstract This paper examines the modeling and speed–based control of an IM–based flywheel energy storage system (FESS) for integration with a variable wind generation system (VSWG) feeding an online isolated load at the DC bus level. Two traditional control strategies are considered for the FESS, rotor flux oriented control (RFOC) and direct torque control (DTC). Instead of controlling the IM torque directly, the proposed schemes control the measured speed of the FESS–IM to follow a reference value estimated from the required power compensation. Matlab/Simulink simulations show that the tracking performance of the two controllers is comparable.

Energy and environmental footprints of flywheels for utility-scale energy storage applications

Flywheel energy storage systems are feasible for short-duration applications, which are crucial for the reliability of an electrical grid with large renewable energy penetration. Flywheel energy storage system use is increasing, which has encouraged research in design improvement, performance optimization, and cost analysis. However, the system's environmental impacts for utility applications have not been widely studied. Evaluating the life cycle environmental performance of a flywheel energy storage system helps to identify the hotspots to make informed decisions in improving its sustainability; to make reasonable comparisons with other energy storage technologies, such as pumped hydro, compressed air, electro-chemical batteries, and thermal; and to formulate environmental policy in the energy sector. In this study, an engineering principles-based model was developed to size the components and to determine the net energy ratio and life cycle greenhouse gas emissions of two configurations of flywheel energy storage: steel rotor flywheel and composite rotor flywheel. The net energy ratio is a ratio of total energy output to the total non-renewable energy input over the life cycle of a system. Steel rotor and composite rotor flywheel energy storage systems were assessed for a capacity of 20 MW for short-duration utility applications. A consistent system boundary was considered for both systems with the life cycle stages of material production, operation, transportation, and end-of-life. Electricity from solar and wind was considered separately in the operation phase. The net energy ratios of the steel rotor and composite rotor flywheel energy storage systems are 2.5–3.5 and 2.7–3.8, respectively. The corresponding life cycle greenhouse gas emissions are 75.2–121.4 kg-CO2eq/MWh and 48.9–95.0 kg-CO2eq/MWh, depending on the electricity source. The net energy ratio and greenhouse gas emissions are highly influenced by the operation phase, which includes charging and standby modes. Uncertainty analysis shows that the life cycle greenhouse gas emissions are most sensitive to the solar, wind, and grid electricity mix emission factors. The results of this study will help to understand the carbon footprints of the various utility-scale energy storage systems.

CCS-MPC for PMSM with Wide Speed Range based on Variable DC-Bus Voltage Control applied to the Flywheel Energy Storage System

In this paper, in order to verify the effect of variable DC-bus voltage control, CCS-MPC (Continuous-Control-Set MPC) control is used to research the control of PMSM (Permanent-Magnet Synchronous Machine) in a wide speed range. In order to maximize the speed of PMSM, the MTPA control, the field weakening control and the variable DC-bus voltage control are applied in the different speed range of PMSM. CCS-MPC can eliminate the control delay by controlling the predicted step size. When CCSMPC is applied to the PMSM control with a wide speed range, the advantages of strong adaptability of CCS-MPC can be exerted.

Intelligent control of flywheel energy storage system associated with the wind generator for uninterrupted power supply

Wind energy is currently the fastest-growing energy source in the world. However, the inherent characteristic of intermittent energy production, due to the stochastic nature of wind, still comprises the main drawback of wind power. To avoid such problems, various configurations have been reccomended in order to reduce output power variation. The paper concentrates on performance benefits of adding energy storage system with the wind generator in order to regulate the electric power delivered into the power grid. Compared with other means of energy storage, the flywheel energy storage system (FESS) is the best choice to solve power quality problems. In this paper, a FESS associated to a variable speed wind generation (VSWG) is investigated by presenting two control strategies applied to the storage system equipped with an induction machine; both techniques are studied and developed and consist of a field control (FOC) and a Fuzzy Logic Control (FLC). Simulation model is established in MATLAB/Simulink and comparative results are then reported.

Control of hybrid power system based renewable energy generations using PID controller

This paper addresses to integrate an optimal Proportional-Integrator-Derivative controller for frequency regulation in an isolated microgrid power system based renewable generation. This autonomous microgrid system is composed of Distributed Energy Sources like wind, solar, Diesel Engine Generator, Fuel Cells system, and two different storage devices such as Battery Energy Storage System and Flywheel Energy Storage System. Optimal tuning of the investigated controller is considered as the main problem to be resolved using the Krill Herd algorithm through an objective function. The obtained results are also accomplished with and without the battery energy storage system. The comparison of system performance shows that the proposed control scheme based Krill Herd Algorithm is better than the Genetic Algorithm in the improvement of system performance.

Integrated Modeling of Power Network and Connected Flywheel Energy Storage System for Optimal Power and Energy Ratings of Flywheel

Power and energy ratings are the most important parameters of Flywheel Energy Storage System (FESS) which have a crucial influence on its dynamic performance in frequency regulation applications. In order to achieve the optimum dynamic performance of FESS, an integrated model is required which includes key parameters of the power network and FESS. In this paper, an integrated transfer function of FESS connected to a single-bus aggregated power system is presented. The proposed model includes both power network and FESS parameters. Moreover, the model is linearized to facilitate the application of the parameter screening approach which recognizes the most influential parameters through Taguchi method. Afterwards, combined Response Surface Methodology (RSM)-GA optimization algorithm is utilized based on an accurate approximation of the system transfer function. In order to obtain FESS power and energy ratings on the basis of lowest capital price and best dynamic response objective functions, optimization algorithm is used. The simulation and experimental studies confirm the validity of the proposed modelling and optimization approach.

Design and implementation of flywheel energy storage system control with the ability to withstand measurement error

In this paper, attempts are made to design an offset and dead zone resistant digitalized vector control system for the flywheel energy storage system (FESS) based on the permanent magnet assisted synchronous reluctance motor (PMa-SynRM). Typically, in the motor drive set, current sensors are used. Current sensors in the industrial application consist of offset and dead zone phenomena and disturb the performance of the control system. Therefore, the effects of these phenomena in FESS designed control system are investigated, and a modified control system with using a proper filter to eliminate these phenomena is proposed. The proposed filter can eliminate these phenomena from the measured current without any decreasing in signal magnitude. The proposed control system eliminates speed ripple caused by the dead zone and offset effects. The performance of FESS is improved under the modified control system. Simulation and experimental results of the modified control system for FESS are presented to verify the performance of the energy storage drive and the theories.

Dynamic Modeling and Simulation of Non-Interconnected Systems under High-RES Penetration: The Madeira Island Case

The defossilization of power generation is a prerequisite goal in order to reduce greenhouse gas emissions and transit for a sustainable economy. Achieving this goal requires increasing the penetration of renewable energy sources (RESs) such as solar and wind power. The gradual shrinking of conventional generation units in an energy map introduces new challenges to the stability of power systems as there is a considerable reduction of stored rotational energy in the synchronous generators (SGs) and the capability to control their power output, which has been taken for granted until today. Inertia and primary reserve reduction have a substantial effect on the ability of the power system to maintain its security and self-resilience during contingency events. Such issues become more evident in the case of non-interconnected islands (NII) as they have unique features associated with their small size and low inertia. The present study examines in depth the NII system of Madeira, which is composed of thermal, hydro, solid-waste, wind and solar generation units, and additional RES integration is planned for the near future. Electromagnetic transient (EMT) simulations are performed for both the current and future states of the system, including the installation of planned variable RES capacities. To alleviate the stability issues that occurred in the high-RES scenario, the introduction of a utility-scale battery energy storage system (BESS), capable of mitigating the active power imbalance due to the power system’s disturbances resultant of RES penetration, is examined. In addition, a comparison between a flywheel energy storage system (FESS) and BESS is shortly investigated. The grid has been modeled and simulated utilizing the open-source, object-oriented modeling language Modelica. The dynamic simulation results proved that battery storage is a promising technology that can be a solution for transitioning to a sustainable power system, maintaining its self-resilience under severe disturbances such as rapid load changes, the tripping of generation units and short-circuits.

Control method for fault ride-through of flywheel energy storage system based on multi-mode coordination

Control method for fault ride-through of flywheel energy storage system based on multi-mode coordination

Forecasting based energy management of flywheel energy storage system connected to a wind power plant

The active power output of a wind power system needs regulation due to the stochastic nature of wind speed. A flywheel energy storage system (FESS) is a viable option for active power regulation in a wind power plant. An efficient energy management system (EMS) for FESS is required for healthy operation of the overall connected system. A wind speed forecasting based EMS has been proposed in this paper. It utilizes the repeated wavelet transform based ARIMA model for very short-term wind speed forecasting, which has been proven to be better than the methods that exist in the literature. An artificial neural network based model is used to translate the forecasted wind speed to instantaneous wind power output. Considering the initial energy of FESS, an optimization technique has been used to calculate the speed command to be given to FESS for a given energy exchanged with the grid. The proposed control approach extends FESS usability as an energy exchange system for a period of large change in wind speed where the normal control approach saturates the FESS speed. The feasibility of the proposed EMS algorithm has been tested in MATLAB/Simulink.

Performance of Flywheel Energy Storage System for Fault Ride through Support of Grid Connected Vsc-Hvdc Based Offshore Wind Farms

For the sake of uninterrupted power supply to the loads we are using renewable energy sources. Among them wind energy and the solar energy is the most familiar renewable energy sources we are using now-a-days. Voltage source converter based high voltage DC transmission is considered as future of offshore power transmission. This paper proposes the high voltage DC power transmission system and maintains system balance during each faults. This results in the voltage and current losses on the switching devices. This strategy implements the flywheel energy storage system based on a squirrel cage induction machine connected in parallel to the grid side converter. It is connected in shunt which present on the grid side circuit of VSC-HVDC based squirrel cage induction motor. Due to this the FESS stores the trapped energy in the DC link during AC side faults for long transmission system using a voltage source converter. When there is insufficient of fault meet the grid at load demand. The series of simulation results we carried out the main part of theFESS system under fault conditions achieved using the software Matlab/Simulink. This project possesses the dynamic performance during ‘steady state’ during normal and fault operating conditions.

Multidisciplinary Design of High-Speed Solid Rotor Homopolar Inductor Machine for Flywheel Energy Storage System

Homopolar inductor machine (HIM) has been applied in the field of flywheel energy storage system (FESS) due to its merits of simple structure, brushless exciting, and low idling losses. The rotor of HIM not only plays the role of energy conversion but also serves as a flywheel to store kinetic energy, which is different from other electrical machines used in FESS. Meanwhile, the HIM usually operates at high speed to improve the power density and storage energy. To obtain good performance and high reliability, the design and optimization of HIM should consider multiphysics, including storage energy, electromagnetic performance, rotor stress and dynamics, and so on. However, the existing researches mainly focus on the analysis of electromagnetic performance and lack multidisciplinary design. To solve this problem, a multidisciplinary design method of HIM is proposed and investigated. First, the operation principle of HIM is illustrated, and the multidisciplinary design method is proposed. Then, the storage energy, electromagnetic performance (including no-load air-gap flux density, saliency ratio, torque, and electromagnetic power), rotor stress, and modal of HIM are deeply analyzed according to the proposed design flow. Finally, a prototype of HIM is manufactured and tested. The results calculated by finite-element analysis are validated by experiments. The design method proposed in this article provides a straightforward procedure for the multidisciplinary design of HIM.