Feasibility Study of Flywheel Mitigation Controls Using Hamiltonian-Based Design for E3 High-Altitude Electromagnetic Pulse Events

One of the current technologies widely used to extract the earth’s renewable energy is solar modules, which harness energy from the sun; however, their operating conditions and their energy storage capacities vary greatly under different weather conditions. The high-speed Flywheel Energy Storage System (FESS) presents a promising prospective solution for solar energy storage and utilization. Accurately modeling FESS can lead to its efficient design and control. In this paper, a fully integrated FESS, with comprehensive photovoltaic (PV) system, has been modeled to simulate the overall energy harvesting capabilities, power output, and efficiency. The solar module has been modeled using the one-diode solar cell model technique to predict the overall system efficiency and determine the most efficient time of day for switching between the FESS’s charging (morning time) and discharging mode (night time). To validate the developed model using experimental data, four 250 Wp Ankara Solar PV modules and a Balance of System (BOS) were installed. The solar irradiance, wind speed, cell temperature, solar module, FESS output voltage and current were logged during the system’s operation. The theoretical model predicted that the energy output for the test day was 4.80 kWh, while the experimental analysis showed that the solar modules produced 4.68 kWh, only 2.5% percentage difference. The theoretical and experimental power curves followed the same trends throughout the day, which assures that the model could accurately predict the daily energy output of the solar array. The efficiency of the solar module was determined to be 15.3%. The solar module simulation serves as a repeatable replication of the actual solar module source, which enables convenient, low-cost estimation of the solar module-FESS system under different environmental conditions. The developed solar module was integrated with a brushless DC motor and flywheel models to simulate the FESS response. Relative to the input solar energy input of 4.68 kWh, the daily energy stored in a flywheel was 3.51 kWh, giving the overall solar-module-FESS system an efficiency of 74.7%. After the experimental setup completion of FESS, the integrated solar module-FESS model will be tested for its overall power output and efficiency against the traditional solar module-battery-system.

Nowadays the flywheel energy storage systems (FES) are developed intensively as uninterruptible power supply (UPS) devices for on-land and transport (especially airborne) applications worldwide. This work is devoted to the FES with magnetic suspension on the base of bulk HTS YBCO elements and permanent magnets. The developed FES is intended to be used as UPS in Russian atomic industry in case of an emergency. For the successful design of the FES the following questions should be solved: design of the motor/generator, design of the rotor (flywheel), design of the bearing system, design of the control system and system of power load matching, design of the cooling system. The developed small-scale FES with the stored energy 0.5 MJ was used to solve these basic questions. The elaborated FES consists of the synchronous electric machine with permanent magnets, the solid flywheel with axial magnetic suspension on the base of YBCO bulks and permanent magnets, the system of control and power load matching, and the system of liquid nitrogen cooling. The results of theoretical modeling of different schematics of magnetic suspension and experimental investigations of the constructed FES are presented. The design of the future full-scale FES with the stored energy ~5 MJ and output power up to 100 kW is described. The test results of the flywheel rotor and HTS magnetic suspension of 5 MJ FES are presented. This work is done under support of Rosatom within the frames of Russian Project "Superconducting Industry"

Chapter Five - Flywheel energy storage

A new flywheel energy storage (FES) system that has a heavy flywheel which rotated in low angular velocity was proposed. In this FES, an induction machine of which the winding connection was controllable was used to eliminate the power converter from the conventional FES system. This reduced the total cost of the FES system, because the price of the electronic power converter is a large part of the total FES system cost. In this paper, the new system configuration was proposed and the operation of the suggested FES system using the induction motor/generator was explained in detail. A new levitation system which consisted of the HTS wire and bulks was proposed. This levitation system was designed to produce a very high levitation force to store the same amount of energy compared to that of the high-speed conventional FES system. At the end of the paper, a conceptual design of a 5 Mj low-speed large-inertia FES system with an induction motor/generator was done.

A flywheel energy storage systems (FESS) is suitable for high-power, low-energy content to deliver or absorb power in surges. This type of application is very suitable for frequency regulation in an electric grid. In addition, a modern FESS is built as a high-efficiency, high-speed motor/generator drive system that employs modern power electronics, therefore, the power quality of the grid-connected output is excellent. In addition, a FESS is very valuable to delivering ancillary services to the grid, and it can contribute reactive power compensation. Thus, a FESS can maintain high reliability in power systems by providing ride-through capability to the power system area while the rest of the generating fleet, which has a slower response in the power system, performs primary and secondary frequency response to the grid. A FESS has several advantages compared to a chemical-based energy storage (CBES) system, namely: it has high energy density and durability, and it can be cycled frequently without impacting performance. The response of FESS is faster than that of a CBES. Also, unlike some CBES, FESS has the same performance regardless of the number of cycles of charging/discharging performed throughout its lifetime.

A novel flywheel energy storage system: Based on the barrel type with dual hubs combined flywheel driven by switched flux permanent magnet motor

Intermittent wind energy in producing optimal power flow could lead to unstable generated power. Due to this, an energy storage that can release and absorb energy need to be used in order maintains the generated voltage at the permitted quality for the load. Nowadays, tons of energy storage systems are used in storing the energy. Flywheel energy storage system (FESS) becomes one of potential mechanism that can be used to smooth the voltage output of wind turbine due to its advantages. The aim of this study is to design and implement a FESS for critical load in a wind energy system that can store energy for a short time period. Then, period of the voltage generated by FESS using different capacitance is analyzed. FESS consists of a self-excited capacitance induction motor-generator set (SEIG), controller circuit and flywheel rotor. In this study, a three phase asynchronous induction machine is used as a motor-generator due to its simplicity, cheap, robust and less maintenance. The flywheel and SEIG-motor set could store the energy for a short period of time, which can be used to compensate for wind instability. Results show that FESS generates variable powers that compensate short time power to the wind system.

We investigated the relationship of power plant mix and required energy storage capacity with a computer model based on global weather data. We focus on energy storage requirements of an electricity supply for Europe by wind and solar power (PV). The minimum required energy storage capacity for a 100% renewable (wind and PV) electricity supply occurs at »30% wind and »70% PV installed capacity. A transition of today’s European electricity supply to a 100% renewable scenario would rise the required energy storage capacity exponentially to about 150 TWh (3.8% of the annual electricity demand). However the installation of excess wind and PV power plant capacity is shown to drastically reduce the required energy storage. For instance 10% excess capacity cut the required storage capacity in half, higher excess capacities lead to further, significant reduction of storage requirements. Furthermore, storage can be separated into daily (short term) storage and seasonal (long term) storage. Seasonal storage capacity has to be about two orders of magnitude larger than storage for the daily cycle, however, the annual sum of stored energy is nearly equal for both types of storage. In summary, an electricity supply by only wind and PV power is shown to be perfectly feasible with respect to the required energy storage capacity and required land area for power plants, and offers competitive electricity generating cost.

Due to its high energy storage density, high instantaneous power, quick charging and discharging speeds, and high energy conversion efficiency, flywheel energy storage technology has emerged as a new player in the field of novel energy storage. With the wide application of flywheel energy storage system (FESS) in power systems, especially under changing grid conditions, the low‐voltage ride‐through (LVRT) problem has become an important challenge limiting their performance. In this paper, we propose a machine‐grid side coordinated control strategy based on model predictive current control (MPCC) for the insufficient LVRT capability of traditional FESS during grid faults. Excellent dynamic properties are demonstrated by the technique, which allows the grid‐side converter output current to swiftly follow the reference current instruction. The FESS's LVRT capability is increased when the grid‐side converter uses the MPCC current inner loop rather than the proportional–integral current inner loop during grid voltage dips. This greatly increases the reactive power response speed and efficiently supports the quick recovery of grid voltage. According to simulation verification carried out by Matlab/Simulink, the suggested control approach can assure the long‐term dependable operation of the FESS during voltage dips. This study can also be used as a reference for improving the FESS's LVRT capabilities in the future.

Energy security and environmental challenges are some of the drivers for increasing the electricity generation from non-programmable Renewable Energy Sources (RES), adding pressure to the grid, especially if located in weakly connected (or isolated) islands, like Sardinia. Variable-speed Pumped Storage Hydro Power (PSHP) can offer a high degree of flexibility in providing ancillary services (namely primary and secondary regulations), but due to the hydro-mechanical nature of the equipment, sudden variations in the power output cause wear and tear. Other energy storage devices cannot compete with PSHP in terms of energy and power availability. The aim of this research is to assess the benefits derived from the hybridization of a PSHP with Battery Energy Storage System (BESS) and Flywheel Energy Storage System (FESS), to be installed in the Sardinia island (Italy). A dynamic model of the hybrid plant was made in MATLAB–Simulink® environment. A detailed model of the variable-speed pump-turbine was obtained from experimental data, and a simplified model of a fixed-speed turbine was produced. A detailed FESS model was provided by CIEMAT (Madrid, Spain) and a simplified BESS model was included. A dedicated control strategy to manage the power flows and accounting for State Of Charge (SOC) control, was implemented. A total of 100 combinations of BESS and FESS powers were taken into account, and the control strategy was calibrated for each one of them. The plant was simulated open-loop over a 3600s time period, feeding historical frequency and Automatic Generation Control (AGC) data. The simulations covered three PSHP operation modes: variable/fixed-speed turbine and variable-speed pump, and with/without hybridization. The performances of the hybridization were evaluated with wear and tear indicators for the PSHP (distance travelled by and number of movements of the wicket gate for turbine, fluctuations of the shaft torque for the pump) and capacity loss (life consumption) for the BESS. The results show that all the combinations of BESS and FESS powers result in the reduction of both the travelled distance and number of movements of the guide vanes. The best hybrid combination for the PSHP does not affect the BESS life consumption, which still is always in an acceptable range. A comparison between the non-hybrid variable-speed turbine and the hybrid fixed-speed counterpart shows that the electric powers do not differ substantially, but the hybridization smooths the movement of the guide vanes. The pump torque fluctuations sharply decrease with the hybridization, but more research is needed to validate that the change in the fluctuation index corresponds to a physical phenomenon. Overall, the hybridization improves the plant performances in terms of wear and tear reduction, and the presence of an additional FESS benefits both the BESS and the PSHP. The results also highlight the necessity for more research in variable-speed pumps providing ancillary services, and their impact.

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

Recently, Flywheel Energy Storage (FES) systems are gaining significant interest from National Aeronautics and Space Administration Glenn Research Center (NASA's GRC) in satellite applications due to their numerous advantages as an energy storage solution over the rest of the alternatives. Regarding FESS features such as high cycle life, long service life, high efficiency, high energy density and low environmental impact, this paper introduces a FESS management controller for use with the solar PV system in an integrated manner that ensures the continuity of the satellite power system and, thus, increases its efficiency. In addition, a prototype of the management control under various operating modes of the proposed unit is established. The satellite power supply management controller was implemented practically as a model using the Arduino controller. The practical results proved the continuity of the satellite operation in different operating modes using the FES system, which in turn would lead to improving the efficiency of the satellite feeding source compared to its performance using solar PV system only.

Recently, governments and concerned private entities have given considerable attention to high-altitude electromagnetic pulse (HEMP) events. Both groups are concerned that a HEMP event would have a serious social and economic impact on our society. However, to date, a limited amount of literature exists that focuses on HEMP events as they relate to substation intelligent electronic devices (IEDs). This paper demonstrates IED resiliency to HEMP events through analysis and test results. It presents substation grounding and wiring practices that are HEMP resilient and also highlights available HEMP standards as they relate to IEDs and substation control houses. This information will help utilities prevent unnecessary mitigation efforts and address the concerns regarding the effects of HEMP on substations and substation IEDs.

The flywheel energy storage system (FESS) is a new type of technology of energy storage, which has high value of the research and vast potential for future development. The FESS has distinct advantages such as high energy storage, high efficiency, pollution-free, wide in application, absence of noise, long lifetime, easy maintenance and continuous working and so on, which provides a new way to solve the terrible energy problem. Its operation principle, and five key technologies including the flywheel rotor, bearing system, energy conversion aspect, motor/generator and vacuum chamber are expounded. Then, the technical evolution of FESS at home and abroad is presented in detail, the application prospect of FESS is also given, and moreover, the research outlook of FESS is pointed out.

Flywheel energy storage systems (FESSs) have been investigated in many industrial applications, ranging from conventional industries to renewables, for stationary emergency energy supply and for the delivery of high energy rates in a short time period. FESSs can be used for industrial applications ranging from aerospace stations and railway trains to electric vehicles (EVs). They have their own individual advantages and disadvantages, leading them to have their own unique roles for energy storage applications. Compared to the limitation of an electrochemical battery imposed by its inherent features, such as low power density, short duration of service, limited charge-discharge cycles and being environmentally unfriendly, FESSs exhibit some distinctive merits, such as high energy density, low cost, high reliability, high dynamics, long lifetime, high efficiency, environmental friendliness and easy monitoring of the state of charge. In this chapter, FESSs applied in EVs are discussed, with an emphasis on those operating at speeds over 10,000 rpm. The organization of this chapter is as follows. In section 3.1, a brief introduction of FESSs is presented. In section 3.2, the configuration of an FESS, including a flywheel, a motor/generator, a bearing, a power converter and an enclosure, is described. Then, in section 3.3, possible candidates for ultrahigh-speed motors/generators for FESSs are reviewed. Lastly, in section 3.4, control strategies for motor/generator control, flywheel control and power flow control are discussed.