refers to a flywheel energy storage flywheel driven by the motor rotates at high speed, and then drives the flywheel energy storage in the power generation mode when needed. Technology is characterized by high power density and long life.
1. Introduction flywheel energy storage
flywheel energy storage idea as early as a hundred years ago it was suggested, but due to time constraints and technical conditions, for a long time did not break. Until the 20th century, 60 to 70 years before by NASA (NASA) Glenn Research Center began as the flywheel energy storage battery used in satellites. In the 1990s, due to a breakthrough in the following three aspects to the flywheel energy storage technology has brought more room for development.
(1) High strength occurs carbon fiber composite material (tensile strength up to 8.27GPa), greatly increasing the kinetic energy per unit mass of the reserves.
(2) Maglev Technology Advances in HTS technology and rapidly, using magnetic levitation and vacuum technology, the flywheel rotor and wind loss frictional losses are reduced to a minimum.
Advances
(3) power electronics technology, such as electric / fatMotors and power conversion technology breakthroughs, providing advanced tools for exchange between the flywheel stores kinetic energy and electrical energy. Flywheel energy storage is a kind of high-tech mechanical and electrical integration products, which in the aerospace (satellite energy storage battery, integrated power and attitude control), military (high-power guns), electricity (power peaking), pass (UPS), automotive industry (electric car) and other fields have broad application prospects.
2. The flywheel energy storage principle
flywheel energy storage system is the storage device for electromechanical energy conversion, break through the limitations of chemical batteries, energy storage physically implemented. By the motor / generator and mutual conversion between kinetic mechanical energy storage inverse reversible motor, and a high speed flywheel energy, and by FM, rectifier, a constant voltage with different types of load interface.
in the charged electrical energy by driving the motor after running power converter conversion, the motor drives the flywheel to accelerate the rotation, the flywheel form of kinetic energy to stored energy to complete the stored energy during the electric energy to mechanical energy conversion, energy storage in the high-speed rotation of the flywheel mass; then, maintain a constant speed motor, a control signal is received until the release of energy; when discharging, high-speed rotation of the flywheel drive motor power, via a power converter output current applied to the load voltage, the release of energy to complete the mechanical energy to electrical energy conversion process. A flywheel energy storage system to achieve the overall energy input, storage and output process.
3. The flywheel energy storage composition structure
flywheel body is the core component of the flywheel energy storage system, is to seek to improve the limit of the angular speed of the rotor to reduce weight of the rotor, flywheel energy storage system to maximize the stored energy, the current use of carbon fiber forming material.
a direct impact on the performance of the bearing system of the flywheel energy storage system reliability, efficiency and lifetime. Currently flywheel energy storage system applications use more magnetic suspension system, to reduce friction during rotation of the motor rotor, reduction in mechanical loss and improve efficiency of energy storage.
convert mechanical energy and electrical energy between
of the flywheel energy storage system based on the motor / generator and controlled to achieve a core, motor / generator an integrated member, when the energy storage, as a motor, by a external power drive motor to drive the flywheel rotor spinning up a set speed; during discharging, but also operated as a generator motor, an output power outwardly, this time falling speed of the flywheel. Obviously, low-loss, high efficiency electric / generator is the key to efficient energy transfer.
In order to improve the power conversion device is the flexibility and controllability of the flywheel energy storage system, power conversion and outputs (frequency modulation, or constant voltage rectification, etc.) to meet the energy requirements of the load power supply.
The main action of the vacuum chamber is to provide a vacuum environment, to reduce windage losses during operation of the motor.
The system includes three flywheel energy storage system rotor portion, the bearing system and an energy conversion system configuration. There are other support systems, such as vacuum, cryogenic, housing and control systems.
1, the rotor system
is proportional to the kinetic energy of the inertia flywheel when the flywheel is rotated. Moment of inertia of the flywheel and is proportional to the flywheel mass and the square of the diameter (J = (0.5 ~ 1) * M * R ^ 2 flywheel, the flywheel mass distribution taken as 0.5, mass completely focused on the edgeWhen taking a margin).
When too large, heavy flywheel rotating at high speed, it will be a great centrifugal force, often more than the ultimate strength of the flywheel material, very safe. Thus, a method of increasing the moment of inertia of the flywheel to increase the kinetic energy of the flywheel is limited.
2, the bearing system
of the rotor bearing support, the support rotor movement, frictional resistance is reduced, so that the entire apparatus runs places with minimal loss.
3, the energy conversion system
of the flywheel energy storage device has a built-in motor, both a generator is an electric motor. When charging, it is operated as a motor to accelerate the flywheel; when discharging, it operates as a generator to power peripheral, at this time the flywheel speed falling; and when the flywheel is idle operation, the apparatus places the entire operation with minimal loss.
none of the flywheel store chemically active substance, and no chemical reaction occurs. Flywheel rotation is purely mechanical motion of the flywheel the kinetic energy during rotation is:
E = 1 / 2Jω / 2, where: J flywheel rotation moment of inertia of the flywheel, [omega] the angular velocity
[. 123] fLYWHEEL technical advantage is high mature technology, non-polluting and unlimited number of charge and discharge characteristics. Flywheel energy storage energy density is not high enough, self-discharge rate, such as stopping the charging, the energy will be exhausted in itself to several tens of hours. Suitable for grid frequency and power quality protection.
4. The flywheel energy storage applications
1, magnetic levitation flywheel store the UPS battery Free
(1) In the normal mains input, the electrical input is low or in the city or higher (A case where a certain range), UPS via its internal Active Filters mains voltage regulator and filter, to provide high quality power to ensure protection to the load device, while the flywheel energy storage device is charged, UPS with built the flywheel energy storage device for storing energy.
(2) can not meet the electrical input mass market normal UPS operation requirements, or in the case of an electrical input mains interruption, UPS stored mechanical flywheel energy storage device where energy into electrical energy, continue to load device providing high-quality and uninterrupted power protection. Case
(3) problems in the UPS internal impact work, UPS switches to the bypass mode switch within its static, providing mains power protection not ask off directly to the load device.
(4) at the mains input power is restored or returned to meet the case where the normal UPS operation required electrical input mass market, it is immediately switched to the mains through the UPS mode, to continue to provide to the load device high-quality and uninterrupted power protection, and continue to flywheel energy storage device is charged.
2, electric car batteries
With the current global energy supply and demand as well as increase the awareness of environmental protection, energy conservation and the use of alternative energy development of environmentally friendly vehicles to reduce pollution of the environment, it is the world an important trend in the development of the automobile industry. Automobile manufacturing industry have turned to the development of electric vehicles. To find large storage density, short charging time, the price for a new type of battery, electric vehicles can have greater mobility and car key compete with gasoline, and the flywheel battery has a clean, efficient, fast charge and discharge , do not pollute the environment and so widely accepted for the automotive industry. Expected in the 21st century will be the hot topic of flywheel battery electric vehicle industry.
3, uninterruptible power supplies
As the uninterruptible power supply to ensure uninterrupted power supply and ensure the quality of power supply is obtained at the local communications hub, defense command centers, control centers of industrial production are widely used at present do not ask off the power a rectifier, inverter, static switch, and a battery and other components. But there is usually a battery operating temperature conditions, Humidity, input voltage, and the depth of discharge requirements. At the same time the battery does not allow frequent closing and opening. The flywheel having a large stored energy, high energy density and quick charging, the charge and discharge cycles unlimited, etc., thus continuouslyField of power systems has a good prospect.
4, the wind power system uninterruptible power supply
Since the wind speed of wind power is unstable, the user to wind creates difficulties in the use. The traditional approach is to install diesel generators, but because of the special requirements of the diesel engine itself, after starting to stop within 30 minutes. The wind often interrupted for a few seconds, a few minutes. Diesel not only frequent start, of life; and after re-start the engine while the fan effect, will cause the power surplus. Considering the large flywheel energy storage of energy. Fast charging, therefore, many foreign research institutions have introduced energy storage flywheel wind power generation system. US flywheel introducing wind power generation system to achieve full peaking, the flywheel power generating units to 300KW, large-capacity energy storage flywheel energy storage to 277KW per hour.
5, pulsed discharge power supply