At present, the improvement of China’s social and economic development level has made the problem of resource scarcity increasingly prominent. Therefore, many regions in China have already started exploring new energy sources in the early stages and have achieved good results. Especially with the introduction of the national “dual carbon” goal, the development of new energy is increasingly valued. But in the field of wind power, the randomness and instability of wind energy have become bottlenecks in wind power development. To solve the instability problem of wind power systems, energy storage technology needs to be adopted.
The content and characteristics of energy storage technology
There are many key technologies involved in energy storage technology. The energy storage system contains a large number of capacitors and superconducting components, which not only convert wind energy into electrical energy during operation, but also store electrical energy in a specific space to ensure subsequent transportation and energy conversion. The function of superconductors is to store electrical energy in superconducting coils and convert it into electrical energy during operation. The application of this technology can achieve rapid transformation in a short period of time and is currently the most commonly used energy storage method in wind energy systems.
There are also some commonly used energy storage methods, such as supercapacitors and flywheel energy storage, which can also convert wind energy into electrical energy. Especially supercapacitors, which can provide a capacity of 30 MJ, can provide stable power supply to users during peak periods. However, in the event of a power grid failure, due to sudden voltage changes and other issues, the expected effect cannot be achieved. Therefore, they can only be used in relatively stable environments to avoid power outages and other dangerous situations.
In wind power generation systems, energy storage needs to take into account both the actual situation and safety analysis. Regardless of which method of storage is used, strict and repeated testing must be conducted before it can be put into use to avoid accidents.
Overview of Wind Energy Storage Technology
With the continuous development of new energy generation, many advanced energy storage technologies have been developed and widely applied and promoted in practical engineering. The application of energy storage technology in wind power generation systems has two advantages: firstly, energy storage technology can improve the stability of the power system and solve the intermittent problem of wind power resources; Secondly, by utilizing energy storage technology, wind power generation systems can operate stably, providing people with more reliable energy supply, meeting large-scale energy needs, and thus effectively utilizing resources. In short, the application of energy storage technology in wind power systems can not only meet the needs of the load side, but also make appropriate adjustments according to the actual situation, improve the stability, adaptability, and economy of the power grid, and improve the overall operational efficiency of the power grid.
The specific application of energy storage technology in wind power generation systems
1.Carbon nanotube supercapacitors
The supercapacitor energy storage device is composed of a current collection device, an electrolyte, an insulator, and two electrodes, which use electrolyte polarization to achieve energy storage. Like batteries, supercapacitor energy storage devices store charges in the form of ions during charging, while supercapacitor storage devices are generally composed of materials such as activated carbon fibers, metal oxides, and carbon nanotubes. Carbon nanotube energy storage devices have high chemical stability and conductivity, as well as high mechanical properties and aspect ratio. They can operate continuously for over 100000 times, have a long service life, high reliability, and do not require any maintenance. They are very suitable for wind farms.
2.Hydrogen fuel energy storage technology
A hydrogen storage device is an electrochemical device that continuously converts the chemical energy of fuel and oxidants into electrical energy. There is no upper limit to the capacity of fuel cell storage devices. According to different electrolytes, fuel cells can be divided into proton exchange membrane fuel cells, direct methanol fuel cells, and alkaline fuel cells. Fuel storage devices are divided into electrolyte, cathode, and anode, and their working principles are the same. At present, the most commonly used fuel storage units in wind energy systems are solid-state storage units and proton exchange membrane fuel storage units.
The working principle of the proton exchange membrane fuel cell (PEMFC) energy storage system is as follows: firstly, hydrogen and fuel gas are introduced into the two poles of the fuel storage equipment through the gas channel of the bipolar plate, and then diffused into the catalytic layer from the position of the membrane electrode; Secondly, the hydrogen gas on the surface of the membrane anode catalyst decomposes into electrons, protons, and water. The electrons reach the cathode through an external circuit in a charged manner and reach the cathode through the sulfonic acid group of the proton exchange membrane. On the surface of the cathode catalyst, oxygen molecules react with the three substances entering the cathode. Hydrogen fuel storage technology can achieve long-term storage, and metallization, liquefaction, and compression are currently the most common hydrogen storage technologies. Hydrogen storage devices can be composed of three modules: fuel storage devices, electrolytic cells, and hydrogen storage tanks, and can be used in wind power systems. When there is more wind power, the electrolysis cell electrolyzes water to produce hydrogen, which is stored in hydrogen containers; During the process of storing hydrogen, the remaining electricity is transferred to the output load. If there is a shortage of wind energy, the hydrogen and oxygen stored in the fuel storage tank react to generate electricity to supply the system load.
3.Hybrid energy storage technology
At present, most domestic wind power generation systems use batteries as energy storage devices, but their energy density is small, their lifespan is short, their maintenance workload is large, and their environmental pollution is severe. Therefore, it is necessary to increase the recycling efforts. Supercapacitor energy storage devices have the characteristics of maintenance free, durable, high energy density, and high efficiency, and are divided into active and passive types. A hybrid energy storage device is generated by combining a battery energy storage device and a supercapacitor energy storage device in parallel. These two parallel ways are used to optimize the charging and discharging process of the battery, extend its service life, improve its technical and economic performance, and improve the conversion efficiency of the battery.
4.Connection of energy storage equipment
Applying energy storage technology to wind power generation systems can improve their operational stability, reduce unit investment, and improve their economic benefits. Before connecting to energy storage, it is necessary to have a comprehensive understanding of the local wind energy characteristics and select appropriate energy storage equipment based on actual needs.
According to different storage methods, energy storage technologies for wind power systems can also be divided into two categories: distributed storage technology and centralized storage technology. Distributed means placing a portion of energy storage devices near a wind farm, and then installing an energy storage device on each generator. Although this method can effectively improve the quality and level of power supply, its drawbacks cannot be avoided. Each unit needs to install an energy storage device, which greatly increases the workload. In addition, the installation process requirements are relatively high during construction. Centralized energy storage technology can also be used in wind power systems. It is a very important energy storage technology that can adjust the input and output of energy storage equipment by adjusting the operation mode of the power grid, improving the flexibility of wind power system applications. At the same time, this technology can also reduce the number of installations and effectively overcome the problems existing in the installation process of traditional distributed storage technology.
(1) Application of Distributed Energy Storage Technology
There are DC lines in wind power generation systems, and in order to use distributed energy storage, a capacitor must be connected to the DC bus. If the wind is not strong, energy storage is used to provide energy to the DC bus, which is transmitted to the DC end by the inverter and then to the power grid to improve system stability. When the wind increases, the remaining energy is also transferred to the DC side, maximizing the utilization of power resources.
(2) Application of centralized energy storage technology
This technology requires connecting the main line of the wind farm to energy storage facilities, storing excess energy, and adjusting it according to on-site conditions. In the event of significant fluctuations in wind resources, the inverter is set to “boost”, thereby changing the operational status of the inverter. During this process, the inverter can also charge the backup battery, thereby achieving the purpose of energy storage.
The Application Prospects of Energy Storage Technology in Wind Power Generation Systems
In wind power generation systems, the power of wind power generation is constantly changing, resulting in uncertainty. With the significant investment in wind power generation systems, the proportion of wind energy is gradually increasing, and the dependence of the power grid on wind power is also becoming increasingly evident. If measures such as limiting the scale of wind farms and reducing the proportion of wind energy connected to the power grid are adopted, it will greatly waste wind energy resources and affect the development of wind power generation. Therefore, how to improve the stability of wind power generation systems has become a highly concerned issue. At present, introducing energy storage equipment into wind farms to form a wind storage combined power generation system is an effective method. Due to the randomness and volatility of wind power, energy storage technology is used for power compensation, which can quickly store and release electrical energy, thus effectively overcoming the randomness and volatility of wind power. By combining wind power and energy storage power generation, an effective control scheme can be designed to reduce the adverse impact of wind power on the power grid to a certain extent and improve the economic benefits of wind power generation.
Another issue is the operating cost of energy storage systems. Whether they can be applied to wind power generation systems depends on improving their energy conversion efficiency and reducing investment. The selection of energy storage equipment often requires a comprehensive consideration of cost, rated power, environmental conditions, and the most important level of maturity of energy storage technology. The first issue that needs to be addressed in order to achieve true energy storage in wind power generation is how to select devices that support wind power energy storage.
In wind power generation systems, energy storage technology is a crucial technology that can ensure the stable operation of the power grid and improve the overall operational quality of the power grid. It is necessary to increase research efforts on energy storage technologies in wind power, adapt to local conditions, and reasonably select suitable energy storage technologies in order to better promote their application in the field of wind power.