Walk into the flywheel energy storage system

1. What is a flywheel energy storage system?

It refers to the energy storage mode that the flywheel is driven by the motor to rotate at high speed, and the electric energy is converted into kinetic energy to be stored, and then the flywheel is used to drive the generator to generate electricity when necessary. Flywheel energy storage system is mainly composed of three parts: rotor system, bearing system and energy conversion system. There are also some support systems, such as vacuum, cryogenic, shell and control system. The basic structure is shown in the figure.

The flywheel energy storage device has a built-in motor, which is both a motor and a generator. When charging, it acts as a motor acceleration flywheel; When discharging, it acts as a generator to supply power to peripherals, and at this time, the speed of flywheel decreases continuously; When the flywheel idles, the whole device runs with minimum loss.

There is no chemical active substance and no chemical reaction in the flywheel energy storage device. The rotating flywheel is purely mechanical, and the kinetic energy of the flywheel is e = 1/2J ω 2.

Where: j is the moment of inertia of the flywheel and ω is the angular velocity of the flywheel.

In practical work, the rotating speed of the flywheel can reach 40000 ~ 500000 r/min, and the flywheel made of metal can't bear such a high rotating speed, so the flywheel is generally made of carbon fiber, which is light in weight and strong, further reducing the weight of the whole system. At the same time, in order to reduce the energy loss (mainly friction loss) in the process of charging and discharging, the motor and flywheel are suspended by magnetic bearings to reduce mechanical friction. At the same time, the flywheel and motor are placed in a vacuum container to reduce air friction. In this way, the net efficiency (input and output) of the flywheel battery can reach about 95%.

Second, the research status, development and future of flywheel energy storage system at home and abroad.

Flywheel battery is a new concept battery put forward in 1990s. It breaks through the limitations of chemical batteries and uses physical methods to store energy, which will not cause pollution due to the mutual transformation of electrical energy and mechanical energy. Flywheel energy storage battery was originally intended to be used in electric vehicles, but it was not developed due to the technical level at that time. It was not until the 1990s that this new battery developed rapidly due to the development of circuit topology, the wide application of carbon fiber materials and the worldwide attention to pollution. With the development of magnetic bearing technology, this kind of battery shows a broader application prospect and is rapidly moving from laboratory to society.

Looking at the current situation in Europe and America, in the automobile industry, American Flywheel Systems Company (AFS) produced the flywheel battery car AFS20 based on Chrysler LHS. On the train side, Siemens has developed a flywheel battery with a length of 1.5m and a width of 0.75m, which can provide 3MW of power and store 30% of braking energy. In military equipment, the United States has begun to try to use flywheel devices, especially large hybrid tractors. The U.S. Department of Defense predicts that future combat vehicles will widely need electric energy in communication, weapons and protection systems. Because of its advantages of fast charging and discharging, independent and stable energy output and light weight, flywheel battery can make the vehicle work in the best condition, reduce the noise of the vehicle (which is very important in combat), improve the acceleration performance of the vehicle, and become the main energy storage device of the US military. In space, due to the high energy storage density of flywheel energy storage devices, and with the continuous development of materials science and magnetic bearing technology, flywheel energy storage devices used in satellites are even small enough to be installed in satellite walls, and the flywheel energy storage devices have little loss during operation and basically do not need maintenance, which makes flywheel technology continuously applied to satellite devices and solar batteries of space stations as their energy supply centers, and flywheel can also be used for attitude control of satellites.

The latest report released by market research company Research and Markets shows that from 20 10 to 20 14, the compound annual growth rate of the global flywheel energy storage market will reach 12%. However, the domestic flywheel energy storage market has only been in operation for three or four years. Developed countries such as the United States, Germany and Japan have developed and applied flywheel energy storage technology. The French National Research Center in Europe, the Institute of Physics and High Technology in Germany and SISE in Italy are all developing flywheel energy storage systems for HTS magnetic bearings. The research of flywheel energy storage mainly focuses on the development of composite technology and superconducting magnetic levitation technology to improve energy density. Superconducting magnetic levitation is the main method to reduce the loss, and composite materials can improve the energy storage density and reduce the volume and weight of the system. 201September, 2004 16 China's first flywheel 200 kW industrialized magnetic flywheel has been successfully debugged, and all the experimental test indexes have reached a good level. The flywheel is running normally and its performance is safe and reliable. According to experts' evaluation, this energy storage technology and product with complete intellectual property rights has filled the gap in domestic technology and market.

At present, some organizations are actively developing flywheel battery system for hybrid electric vehicles. Its main functions are: a) to stabilize the power output of the main power supply. In the process of starting, climbing and accelerating the hybrid electric vehicle, the flywheel battery can discharge quickly and with great energy, providing auxiliary power for the main power source and reducing the power output loss of the main power source. B) Improve the efficiency of energy recovery. When the hybrid vehicle is downhill, skidding and braking, the flywheel battery can quickly store a large amount of kinetic energy, and the charging speed is not affected by the chemical reaction speed of "active substances", which can improve the energy recovery efficiency during regenerative braking. When flywheel energy storage is used in hybrid electric vehicles, the main problem is how to minimize the gyro effect of flywheel and improve the working efficiency of flywheel. For the same class of cars, after installing the flywheel energy storage system, a relatively small engine can be used to provide power to achieve the purpose of energy saving and emission reduction. Recently, when the Ministry of Industry and Information Technology issued the "Detailed Rules for the Administration of New Energy Vehicle Manufacturers and Products Access", it especially wrote high-efficiency energy storage devices as one of the ways to solve new energy sources into the detailed rules. As a representative of high-efficiency energy storage device, flywheel energy storage has great application potential in automobiles. It is said that the specific energy of flywheel battery can reach 150W? H/kg, the specific power is 5000- 10000W/kg, the service life is as long as 25 years, and the electric vehicle can travel 5 million kilometers.

Flywheel energy storage technology seems mysterious, but it is actually closely related to people's lives, such as the energy conversion when subway trains enter and leave the station, the excess energy is input to the flywheel when the train stops, the energy is needed to speed up when the train leaves the station, and the flywheel outputs energy. The system can save about 20% energy consumption for subway. Flywheel technology is still in the research and development stage in China, while developed countries have developed for decades, and it has been applied in many fields, such as F 1 racing car energy recovery, track traction energy recovery, micro-grid voltage regulation and grid connection, ultra-low temperature waste heat recovery and utilization, emergency UPS power supply, high-speed centrifugal fan and so on.

Third, the advantages of flywheel energy storage system

Flywheel energy storage technology is one of the most promising energy storage technologies at present. Compared with lithium batteries and lead-acid batteries, flywheel energy storage has many advantages:

1, high energy storage density. The energy storage density can reach 100 ~ 200 Wh/kg, and the power density can reach 5000 ~ 10000 W/kg.

2. High efficiency. The working efficiency is as high as 95%

3. Low maintenance cost. The running loss is very small, and there is basically no maintenance.

4, long life. Not affected by repeated deep discharge, the design life is more than 20 years, the mechanical loss caused by magnetic bearing and vacuum environment can be ignored, and the system maintenance cycle is long.

5, no noise.

6, little environmental pollution, almost no impact on the surrounding environment.

It is one of the most promising energy storage technologies at present.

Fourth, the shortcomings of flywheel energy storage system

The energy density is not high enough, and the energy release can only last for a short time, usually only a few tens of seconds. High self-discharge rate. If you stop charging, the energy will run out in a few to dozens of hours. The flywheel energy storage system of the main power company has an output of 250 kW per module and a standby loss of 2.5 kW, so some data claim that its efficiency is 99%. But there are conditions. Only when you use it quickly can you be so efficient. If self-discharging, the efficiency will be reduced. For example, the loss of tens of thousands of high-speed flywheel systems is about 1 00W, and the system with1kWh can only maintain 10 hour self-discharge. Therefore, flywheel energy storage is most suitable for high power, short-time discharge or frequent charge and discharge.

Verb (abbreviation of verb) Current application field of flywheel energy storage system

Due to the limitation of process and material price, the price of flywheel battery is relatively high, which can not reflect its advantages in small occasions. However, in the following occasions where large-scale energy storage devices are needed, the price of using chemical batteries is also very expensive, and flywheel batteries have been gradually applied.

1. Space includes satellites, spaceships and space stations. The flywheel battery can provide twice the power of the chemical battery with the same weight at one charge, and the service time of the same load is 3 ~ 10 times that of the chemical battery. At the same time, because its speed can be measured and controlled, you can check the amount of electric energy at any time. NASA has installed 48 flywheel batteries on the space station, which together can provide more than 150 kW of power. It is estimated that it can save about $2 million compared with chemical batteries.

2. Transportation includes trains and cars. This kind of vehicle is driven by internal combustion engine and motor, and the flywheel battery charges quickly and discharges completely, which is very suitable for vehicles driven by mixed energy. When the vehicle is running and braking normally, the flywheel battery is charged. When the vehicle is accelerating or climbing, the flywheel battery provides power for the vehicle, ensuring the vehicle to run at a stable and optimal speed, which can reduce fuel consumption, air and noise pollution, engine maintenance and prolong engine life. The University of Texas has developed a flywheel battery for FAW vehicles, which can provide 150KW energy when vehicles need it, and can accelerate fully loaded vehicles to100km/h/h. ..

In the last round of the 20 10 Le Mans Series, the Porsche 9 1 1GT3 hybrid car officially used this technology for the first time (the car ranked in the middle of the race). 9 1 1 GT3 is Porsche's first hybrid racing car and the predecessor of 9 18 Spyder hybrid car. Flywheel technology makes cars more efficient without sacrificing speed and agility, which is an exciting progress-Porsche 9 18 Spyder hybrid car has 500 horsepower all-wheel drive, which takes only 3.2 seconds. Porsche said that 900 potential buyers have signed up to buy the car.

3. Uninterruptible power flywheel battery can provide highly reliable and stable power supply, which can provide electric energy for several seconds to several minutes, and has enough time to ensure power switching in the factory. German GmbH has made a UPS using flywheel battery, which can provide or absorb 5MW of electric energy in 5 seconds. Foreign data show that flywheel energy storage is gradually replacing lead-acid batteries and becoming the mainstream technology in UPS applications.

4. Military combat vehicles

As a new energy storage method, the advantages of flywheel battery over traditional chemical battery have been widely recognized, which is in line with the development direction of energy storage technology in the future. In addition to the application fields mentioned above, flywheel batteries are also developing towards miniaturization and low cost. The most likely is the cell phone battery. It can be predicted that with the progress of technology and materials science, flywheel batteries will play an important role in all walks of life in the future.

About micro-control new energy

Shenzhen Micro-control New Energy Technology Co., Ltd. (referred to as micro-control or micro-control new energy) is a global leader in physical energy storage technology. The company is headquartered in Shenzhen, covering North America, Europe, Asia, Latin America and other regions. With the "safe, reliable and efficient" global leading magnetic levitation energy technology, its products and services are widely trusted by many Fortune 500 companies such as Huawei, GE, ABB, Siemens and Emerson.

Facing the three major trends of "cleaner, high-density and digital" energy in the future, the company continues to provide systematic solutions for energy transportation, storage, recycling and data management for strategic emerging industries.