 The technology principle This section uses a double-layer capacitor as an example to describe the working principle of a supercapacitor. Double-layer supercapacitor is a new energy storage device that relies on polarized electrolyte to store electric energy. Its principle structure is shown in the figure. In a double-layer capacitor, electrical energy is stored in an electrostatic field between the electrodes and the ions of the electrolyte. When the electrode is charged, the charge on the surface of the idealized electrode will attract the opposite ions in the surrounding electrolyte solution, so that these ions attach to the electrode surface to form a double charge layer and form a double electric layer capacitance. Because ultracapacitors store charge over a much larger area and are isolated over a much smaller distance than conventional capacitors, the capacitance of a single ultracapacitor unit can be as high as several to tens of thousands of fuses. Because of the special process, the equivalent resistance of the supercapacitor is very low, the capacitance is large and the internal resistance is small. As a result, the super capacitor can have a high peak current, so it has a high specific power, up to 50 ~ 100 times of the battery, up to about 10kW/kg. This feature makes the super capacitor very suitable for short-time high-power applications. Application scenarios Public transportation/electric cars The composite power system composed of ultracapacitors and other energy storage components takes into account the advantages of high specific energy of other energy storage components and high specific power of ultracapacitors, which can better meet the requirements of the start and acceleration performance of electric vehicles and improve the recovery efficiency of braking energy of electric vehicles. Increase driving range. Currently, ultracapacitors can be combined with batteries, fuel cells, flywheel batteries and other power systems. It will be one of the important directions in the future development of electric vehicle field to adopt supercapacitor - battery composite power system in pure electric vehicle and hybrid electric vehicle. Wind power generation Wind power generation is the fastest developing renewable energy generation technology. However, wind energy is a kind of energy with random variation. The variation of wind speed will lead to the fluctuation of the output power of wind turbine, which will affect the power quality of the power grid. Therefore, the output power regulation of grid-connected wind farms has become an important issue in wind power generation technology. Additional energy storage equipment can not only adjust reactive power, stabilize bus voltage of wind farm, but also adjust active power in a wide range, which is a research focus at present. With the development of manufacturing technology, the energy density of supercapacitor has been greatly improved, and it has entered the stage of commercial application in some short-time power storage occasions. It has a good application prospect to use supercapacitors to store energy and suppress the wind power fluctuation in the important frequency band of the output power of wind farms. Microgrid/grid In the operation of micro-grid, when the total power generation capacity is less than the total load demand and the island runs due to external faults, the secondary loads must be removed to protect the important loads. If the external faults are instantaneous faults, the micro-grid will overlap with the main network in a short time due to the disappearance of instantaneous faults and restart the secondary loads. From the perspective of power supply stability and economy, it is not good for secondary load. Therefore, after external failure, ultracapacitors can be used to provide short-term power deficiency to the micro-grid operating on the island, maintain all loads and wait for fault repair. |