Application of energy storage technology in urban power grid

Application of energy storage technology in urban power grid

①Reduce the operating costs of power generation companies and power grid companies, and reduce users’ electricity costs
The operation and maintenance of the energy storage system is relatively simple, while the operation and maintenance of the power plant or the power grid are relatively complicated. After the energy storage system is put into operation, the operation and maintenance costs of the power plant and the power grid can be greatly saved.
For power plants, in order to ensure the power balance during low load conditions, most large thermal power units have to reduce their output to the minimum, and small units need to be turned on and off day and night, and operate in two shifts. This is critical to the safety and economy of unit operation. Very unfavorable. Take Shanghai’s 300MW unit as an example. When the unit output is 300MW, the coal consumption for power generation can be controlled at about 320g/(kW·h), and when the output is reduced to 120MW, the coal consumption rate is as high as about 400g/(kW·h), which is very economical. After the large-scale application of the energy storage system, the energy storage device can be started for energy storage under low load conditions, and the unit can operate in a more economical output range, thereby obtaining higher economic benefits.

Application of energy storage technology in urban power grid
Energy storage system grid

Once the energy storage system is scaled up and the unit efficiency at low load is improved, even considering the storage efficiency of the energy storage system, 50 to 150 kW·h of electricity can be generated per ton of standard coal. At the same time, the large-scale application of energy storage systems can not only improve the economic benefits of power plants, but also promote their efficiency and emission reduction under the same power generation, which is in line with the national energy policy and has obvious social effects.

For power grid companies and terminal users, the energy storage system can optimize resource allocation from the peak-to-valley power price difference by storing power at night and discharging during the day, and obtain a lot of economic benefits.

②Suppress system low-frequency oscillation
The so-called low-frequency oscillation is the generator’s rotor angular speed, rotational speed, and related electrical quantities, such as line power, bus voltage, etc., which have approximately equal amplitude or increased amplitude. Because the oscillation frequency is low, generally 0.1-~2.5 Hz, it is called Low frequency oscillation.

Low-frequency oscillations are caused by the interconnection of power grids. In the early stage of networking, the synchronous generators are closely connected, the damping winding can produce sufficient damping, and low-frequency oscillations rarely occur. With the expansion of the grid interconnection scale, the widespread adoption of high-magnification rapid excitation technology, and the operation of the grid under the influence of economic and environmental factors, the operation of the grid is closer to the stability limit, and low-frequency oscillations have been observed in many grids around the world.

Low-frequency oscillation can be divided into two types: local mode oscillation and regional mode oscillation. Generally speaking, the more units involved and the wider the area, the lower the oscillation frequency. It is generally believed that low-frequency oscillation is the power swing on the tie line after the power system is disturbed. System dynamic instability is caused by divergent oscillations caused by insufficient damping or even negative damping after disturbance. Instability is mainly caused by insufficient electrical damping of the system or lack of appropriate active power coordination. It is usually caused by the following disturbances: ①cutting the machine; ②transmission line failure or protection malfunction: ③breaker equipment accident; ④loss of load. Disturbance phenomena generally go through the process of generation, propagation, and dissipation. In the process of propagation, new disturbances may be caused. At the same time, the operation for disturbance is also a kind of disturbance. Therefore, these situations are often not isolated, but interrelated, showing multiple phenomena in time and space.

The application of energy storage technology can change the traditional way of thinking about power system stability control, help people understand the stability of the power system from a new perspective, and seek a method that may completely solve the stability of the power system. The traditional Power System Stabilizer (PSS) can effectively suppress the local oscillation of the system through the additional excitation control of the generator. However, the most effective control is for the inter-regional multi-mode low-frequency oscillation problem that occurs in the large and complex interconnected power system. The point may be located on a certain transmission line far away from the generator set. The PSS must be controlled by the generator set’s excitation. It is far away from the most effective control part of the system, and it is often difficult to achieve satisfactory control results. The application of energy storage technology can provide a very simple and effective way to solve this problem. In the traditional power system, the dynamic unbalanced power caused by any small disturbance will cause the oscillation between the units; and the energy storage technology can realize the complete balance of the system power under any circumstances as long as the capacity of the energy storage device is large enough and the response speed is fast enough. . Since this kind of power system stability control device does not have to work together with the excitation system of the generator, it can be conveniently used in the most effective part of the system for suppressing oscillation. At the same time, because the control quantity produced by this control device can directly act on the source of system oscillation, it can “precise” compensation for unbalanced power, which can reduce or even ignore the influence of system operating state changes on the control effect of the controller. Therefore, the parameter setting of the device is very easy, and the robustness of the controller to the change of the system operating state is also very good.

③Promote the development of electric vehicles
As the key and necessary energy storage equipment in new energy vehicles, energy storage systems play a pivotal role. So far, the development of human society has realized the importance of protecting nature and harmonious development, and advocated low-carbon environmental protection, production and life in harmony with nature. As an indispensable means of transportation for people’s lives, with the ever-decreasing oil reserves, the huge number of automobiles and the entire automobile industry are ushering in an important transitional stage, that is, energy-saving automobile use. Decarbonization and emission reduction of pollutants. In this regard, traditional cars are required to reduce fuel consumption and environmental pollution through technological upgrades and the use of new materials in various links. On the one hand, it requires the research and development and market promotion of new energy vehicles.

Application of energy storage technology in urban power grid
New energy vehicles and power grids

New energy vehicles mainly refer to fuel cell vehicles, pure electric vehicles and hybrid vehicles, etc. There have been some practices in their development and use, and certain results have been obtained. Countries in the world such as the United States, Japan, Germany, France, etc. are actively promoting the development and marketization of new energy vehicles. In this process, some key technical difficulties and bottled goods are unavoidable: as a product that converges a variety of technologies and parts, new energy vehicles are currently market-oriented problems such as a wide variety of models and difficult to unify models and sizes. . Among them, the advanced power battery as the GO source of new energy vehicles plays an extremely important role, affecting the main performance of new energy vehicles such as the cruising range, accelerating DIA energy, charging and discharging conditions, and daily safety maintenance.

New energy vehicles are powered by electric energy and can achieve zero emissions and low noise during operation. They are an important means to solve energy and environmental problems. The construction of a strong smart grid will greatly promote the development of new energy vehicles, including the establishment of a complete new energy vehicle supporting charging and discharging infrastructure network, forming a scientific and reasonable new energy vehicle charging and discharging station layout, and charging and discharging station infrastructure to meet the new energy automobile industry Development and consumer needs, the efficient interaction between new energy vehicles and the power grid has been fully applied. Compared with traditional fuel vehicles, new energy vehicles also have a series of problems such as long charging time, short driving range, and high cost of use. Among them, energy storage technology is the main bottleneck hindering the development of the new energy automobile industry, and the development of energy storage technology will surely drive the greater development of the new energy automobile industry.