Development trend of flywheel energy storage technology and superconducting energy storage technology

The development trend of flywheel energy storage technology

With the maturity of flywheel energy storage technology, flywheel products have begun to be applied in industries, transportation, electric power, aerospace, military and other fields. The future breakthroughs and trends of flywheel energy storage technology are mainly concentrated in the following aspects:

(1) Flywheel energy storage will focus on the research and development of new materials in the future. For low-speed-large-mass flywheels, the outer circumferential speed of the flywheel rotor is not very demanding, and metal materials such as martensitic steel or aluminum alloy can be used; however, the high-speed-small-mass flywheel has a high energy storage density and requires composite materials with high specific energy and specific strength such as fiber-reinforced resin matrix composite materials. The development of new materials with high specific strength is the focus of future work.

(2) Develop flywheel rotor processing technology. In the future, the flywheel energy storage technology will be dedicated to solving the prominent system vibration problem caused by the high speed of the high-speed-small-mass flywheel. R & D and manufacture of fiber composite materials wound into thin-wall fiber cylinders, to overcome the process problem of multi-layer cylinder interference press assembly.

(3) Develop flywheel rotor support technology. The rotor support system is developed on the basis of permanent magnetic bearings, electromagnetic bearings, superconducting suspension bearings and mechanical bearings, and the design and manufacture of flywheel systems that support high-speed rotation and continuous discharge, overcome its dynamic characteristics and vibration problems, and improve the stability of the system. It is the direction of future research and development.

(4) Study how to maintain vacuum. The flywheel system needs to provide a vacuum environment for the high-speed rotating flywheel rotor to reduce wind loss and improve energy conversion efficiency. The flywheel system needs to be equipped with a vacuum pump, which monitors the internal vacuum of the system in real time through sensors, and uses a control module to start the vacuum pump in a timely manner to maintain its high vacuum. Although it is not difficult to obtain vacuum, how to obtain a long-term high-vacuum environment with as little electrical energy as possible is the focus of flywheel product research and development.

(5) Flywheel energy storage technology will devote itself to the development of electric energy conversion technology, so as to convert the input electric energy into direct current to supply the motor, and the output electric energy is frequency-modulated and rectified to be supplied to the load. The research will focus on power conversion control systems, magnetic bearing controllers, power amplifiers, and other auxiliary electronic equipment power conversion and control technologies.

The development trend of superconducting energy storage technology

From a technical point of view, superconducting energy storage has a series of advantages that other energy storage technologies cannot match. For example, superconducting energy storage technology has the characteristics of rapid response and convenient control. SMES is connected to the AC system through a converter, and the response time can reach the ms level; the conversion efficiency is high, the energy loss is 0.1%/h, and the conversion efficiency can reach 95%; it is flexible to use, has the advantages of small size and low quality, especially small or micro devices, which can be made into mobile; it can provide high power to the grid in a short time; it has a long service life, simple maintenance and low pollution.

However, most of the practical superconducting energy storage technologies are still in the research stage at this stage. The technical problems and development trends to be solved in the future are in the following aspects:

(1) Development in research on new technologies of superconducting wires. At present, the technology of low-temperature superconducting wire is mature, but the investment in maintaining the temperature zone of liquid ammonia is large, and the economy is not high; the technology of high-temperature superconducting wire is immature, the AC loss is large, and the safety and stability is low. Therefore, further research and development of high-temperature superconducting wires and increasing the critical current density of high-temperature superconducting wires are one of the development trends of superconducting energy storage technology in the future.

(2) Development in the field of converter research and development. In the future, we will further study the parallel technology of current uniformity to reduce high-order harmonics to reduce converter losses.

(3) Development in control strategy. In the future, we will devote ourselves to designing a stable control system that meets a variety of different parameters and control items.

(4) Development in quench protection technology. In the future, it will focus on the research and development of how to quickly and accurately detect the quench of the high-temperature superconducting energy storage device and protect the magnet after the quench.

In addition to the clearer technological development trends above, reducing costs, reducing losses, and improving stability are also trends in the development of superconducting energy storage technology.