In the traditional power production process, the generation, transmission,
distribution and use of electric energy occur almost simultaneously. This
characteristic greatly affects the planning, construction, dispatching operation
and control methods of the power system. The application of large-capacity
energy storage technology breaks the restriction of real-time balance of power
supply and demand. Its large-scale application can effectively reduce the peak
and valley difference between day and night, improve the stability of the power
grid and power quality level, and promote the large-scale integration of new
energy into the power grid. The application of energy storage technology in
power systems has become an inevitable trend in the development of future power
grids [1−5].
This article introduces the current research and application status of
various energy storage technologies, combines the different application scopes
of energy storage technologies, analyzes and proposes energy storage technology
application models and operation control methods suitable for China Southern
Power Grid.
1 Current status of research and application of energy storage
technology
1.1 Pumped hydro storage
Pumped storage is currently the most widely used energy storage technology
with the longest life cycle and largest capacity in the power system. It is
mainly used for system backup and peak and frequency regulation. During the low
load period, the pumped storage equipment works in the motor state, pumping
water to the upstream reservoir for storage, and during the load peak period,
the equipment works in the generator state, using the water stored in the
reservoir to generate electricity. The full life cycle of a pumped storage power
station can reach more than 40 years, and its comprehensive efficiency is
generally around 75%.
As of the end of 2008, the scale of pumped storage power stations in
operation nationwide reached 10,945MW, accounting for approximately 1.38% of the
total installed power generation capacity in the country [6]. However, due to
factors such as high station site selection requirements, long construction
period, and relatively slow unit response speed, the large-scale promotion and
application of pumped hydro energy storage is subject to certain
constraints.
1.2 Flywheel energy storage
Flywheel energy storage technology combines the rotor of the motor with the
flywheel, and uses the motor to drive the flywheel to high-speed rotation so
that energy is stored in the high-speed rotating flywheel body; when the system
needs electrical energy, the high-speed rotating flywheel can be used to drive
the generator to generate electricity. The comprehensive efficiency of flywheel
energy storage is relatively high, which can reach 85% to 90% [7].
Foreign flywheel energy storage systems have formed a series of commercial
products, such as Active Power's 500kWClean SourceDC and Beacon Power's Smart
Energy Matrix energy storage system composed of 10 25kWh units [1,3]. At
present, flywheel energy storage devices have been put into actual operation on
the power grid. For example, the New York Power Administration has
experimentally installed a 1MW/5kWh flywheel energy storage device to solve the
voltage mutation caused by electric locomotives. Flywheel energy storage has
good load tracking and fast response performance, and can be used in
applications with small capacity, short discharge time, but high instantaneous
power requirements [1].
1.3 Compressed air energy storage (CASE)
The essence of compressed air energy storage is a gas turbine power plant.
Its principle is to compress and store air in high-pressure sealed gas storage
cavities, such as underground lava caves, seabeds, abandoned mines, tunnels and
other storage spaces, and release it during peak power consumption. Driving a
gas turbine to generate electricity.
Large foreign equipment manufacturers such as ABB and GE are focusing on
the research and development of hundreds of megawatts of compressed air energy
storage. At the same time, the United States is planning to build the world’s
largest compressed air energy storage power station with a total installed
capacity of 2,700MW in Ohio [1]. Generally speaking, the construction cost and
power generation cost of compressed air energy storage are lower than that of
pumped storage power station. However, since the construction of gas storage
cavity is limited by terrain conditions such as rock strata, the key to
popularization and application is to choose a more appropriate gas storage
method.
1.4 Superconducting Magnetic Energy Storage (SMES)
The main principle of superconducting magnetic energy storage technology is
to store electrical energy in the form of electromagnetic energy in
superconducting coils. Superconducting magnetic energy storage has the
advantages of high power density (10-100MW/kg), high overall efficiency (about
95%) and fast response speed (millisecond level) [1-4,8].
SMES has been initially used in the United States, Japan and Europe, and
100MJ SMES has been put into trial operation. However, the only commercially
produced superconducting magnetic energy storage system in the world is the
D-SMES system of American Superconducting Company, with an energy storage
capacity of 3MJ (equivalent to approximately 0.83kWh). At present, the device
has been put into actual operation on the power grid in many places such as
Alliant Energy and Entergy in the United States, and is mainly used for voltage
stability control and power quality regulation [1].
1.5 Supercapacitor
The energy storage principle of supercapacitors is the same as that of
conventional capacitors, but the distance between the charge layers is reduced
to less than 0.5nm. In addition, the use of special electrode materials
increases the surface area of the two electrodes tens of thousands of times,
thus producing
Produced a huge capacitance.
Currently, various commercially produced supercapacitors have small single
energy storage capacities, generally only 8 to 50kJ (equivalent to about 2 to
14Wh), and the unit capacity price is still relatively expensive. They are
mostly used in high-voltage substations and switching stations in power systems.
Capacitor energy storage silicon rectifier opening and closing devices, starting
support for high-power DC motors and dynamic voltage recovery and other
ultra-short discharge time, instantaneous high-power occasions [1,9].
1.6 Battery energy storage
Battery energy storage is also called electrochemical energy storage. The
current technical parameters of various mainstream energy storage batteries are
shown in Table 1 below.
Lead-acid battery technology is mature and low-cost, and it has always
occupied a dominant position in the application of battery energy storage
technology in power systems. However, due to problems such as low energy density
and short cycle life, there are currently no relevant new application projects;
various aspects of nickel-cadmium batteries The performance index is close to
that of lead-acid batteries, but due to the memory effect and self-discharge
phenomenon, as well as the problem of cadmium metal contamination, its use has
been restricted by the European Union and does not have the potential to be
promoted and applied in power systems; sodium-sulfur batteries have been
developed in the past 20 years It is rapid, has the advantages of high energy
density and long cycle life, and has been used in a large number of practical
engineering applications in Japan and the United States [12−14]. Flow batteries
gradually achieved commercial production at the beginning of this century. They
have the advantages of being able to discharge 100% deeply and increasing the
battery capacity by increasing the concentration of the electrolyte. However,
the current energy density of flow batteries is low and the unit cost is
expensive, which restricts their large-scale development [15].
Lithium batteries and nickel-metal hydride batteries are currently the most
promising large-capacity energy storage batteries. Lithium batteries are the
energy storage batteries with the highest energy density and comprehensive cycle
efficiency [16]; nickel-metal hydride batteries are an improvement of
nickel-cadmium batteries and have no memory effect and no environmental
pollution. However, the above two energy storage technologies have few practical
applications in power systems, and they still need to undergo long-term safety
and reliability operation tests before being promoted and applied.
Overall, electrochemical energy storage technology has the advantages of
high energy density, high overall efficiency, short construction period, and
wide application range of capacity and power scale. With the maturity of
large-capacity integration technology and the further reduction of comprehensive
costs, it is expected to play an important role in peak shaving, frequency and
voltage regulation, power quality regulation, system backup, and flexible access
to renewable energy in the power system.
2Analysis of applicable scope of energy storage technology
The application modes of energy storage technology can be divided into two
types: capacity type and power type. Different application modes and application
occasions put forward different requirements for the performance indicators of
energy storage technology. The specific demand ranges of energy storage power
scale and discharge time for various application modes are shown in Figure 1
[17].
Application modes such as peak shaving and valley filling, frequency
adjustment and system backup in the power system place higher requirements on
the capacity of energy storage equipment, which is a capacity-based energy
storage application mode. On the other hand, system stability control and power
quality regulation application modes are power-based energy storage application
modes, which require the energy storage system to have a fast response speed and
provide sufficient instantaneous power dynamic support to the power grid. In
addition, the application model that supports the access of renewable energy has
wider requirements for the capacity and power scale of the energy storage
system, which mainly change according to the different power generation
characteristics and installed capacity of renewable energy.
Generally speaking, there is currently no single energy storage technology
that can fully meet the needs of all application modes. Appropriate energy
storage technologies need to be selected according to the technical requirements
of different application modes. The specific performance characteristics of
various energy storage technologies are shown in Table 2.
3 Analysis of the application prospects of energy storage technology in
China Southern Power Grid
3.1 Support flexible access to new energy sources
Renewable energy power generation such as wind energy and solar energy has
the characteristics of randomness, intermittentness, and rapid changes in
output. Some studies have pointed out that once the proportion of renewable
energy in installed capacity exceeds 10%, it will have a significant impact on
local power grids. Especially in areas with a small proportion of water, oil,
and steam power sources, it is difficult for thermal power units with slow
active power regulation to fully adapt to the rapid changes in their output, and
may even cause large-scale vicious accidents [18].
At present, the scale of renewable energy sources such as wind power and
photovoltaic power within the jurisdiction of China Southern Power Grid is
relatively small. As of the end of 2010, the five southern provinces (regions)
had coordinated wind power installed capacity of 947MW, accounting for 0.6% of
the entire network. Therefore, it has little impact on the safe and stable
operation of the power grid. However, the next five to ten years will be a
period of great development of new energy. Research on large-capacity energy
storage technology that operates jointly with renewable energy generation,
through real-time adjustment of the charging and discharging power of the energy
storage system and rapid switching of charging and discharging states,
Converting the randomly changing output power of renewable energy into a
relatively stable output, thereby ensuring the safe and stable operation of the
power grid, has become the key to meeting the needs of flexible access to new
energy sources in China Southern Power Grid in the future.
3.2 Peak shaving and valley filling
With the substantial growth of electricity consumption by urban and rural
residents and industrial production, the absolute value of the peak-valley
difference between power loads is increasing day by day, which will cause a
series of difficulties in power dispatching. The power generation contradictions
between provinces (regions) and between various types of power plants will also
It is becoming increasingly prominent and may even cause intensification of
conflicts on the power generation side. With the successive commissioning of
hydropower plants in the China Southern Power Grid region during the 12th
Five-Year Plan period, the difficulty of system peak regulation continues to
increase. There are still large peak peak regulation shortages in Yunnan and
Guangxi during the flood season, and it is inevitable to abandon water supply
for peak regulation.
At the same time, as the current peak load of the power grid continues to
increase, power grid companies need to continuously invest in transmission and
distribution equipment to meet the capacity requirements of the peak load,
resulting in a low overall load rate of the system and a low comprehensive
utilization rate of assets.
Therefore, establishing an economical and efficient large-capacity energy
storage system can store electrical energy as a load during low power
consumption periods, and release electrical energy as a power source during peak
power consumption periods, thereby achieving decoupling and load regulation
between power generation and electricity consumption. Peak and valley
differences. Once the energy storage system reaches a large scale, it can
effectively delay or even reduce the construction of power sources and power
grids, improve energy utilization efficiency and overall asset utilization of
the power grid, completely change the construction model of the existing power
system, and promote its transformation from an extensional expansion type to a
connotation efficiency enhancement type. change.
The application of energy storage systems in peak shaving and valley
filling is one of the important ways to alleviate environmental pressure and
meet the development of a low-carbon society in the future.
3.3 Grid stability control
The characteristics of China Southern Power Grid's long-distance,
large-capacity, and AC-DC parallel power transmission determine that ensuring
the safe and stable operation of the power grid will remain the development
theme of China Southern Power Grid for a long time. At present, the energy
storage capacity of China Southern Power Grid accounts for a small proportion,
and all of them are pumped storage power stations. The response speed cannot
fully meet the requirements of dynamic support of the system, making it
difficult to fundamentally prevent the occurrence of large-scale power outages.
Power grid stability control should adopt fast-response power energy storage
technologies such as electromagnetic energy storage and flywheel energy storage
[15], which can effectively reduce and eliminate the impact of disturbances on
the power grid, and quickly absorb/emit power when a system failure occurs,
thereby Suppress system oscillation and comprehensively improve the reliability
of system operation.
However, power energy storage technologies such as superconducting magnetic
energy storage and flywheel energy storage are still in the preliminary stage of
commercialization, are expensive, and their products are not yet fully mature.
The maximum scale that has been put into actual operation of the power grid is
about 1MW/250kWh, which is different from the main grid. The scale of power
transmission is very different. According to relevant information on the
critical capacity requirements of energy storage systems to suppress
low-frequency oscillations, the current overall production level of
superconducting magnetic energy storage and flywheel energy storage technologies
cannot meet the requirements for grid stability control at the main grid level.
Therefore, in the near future It does not have the strength to promote and apply
it on a large scale in the transmission network.
4 Some suggestions for the application of energy storage technology
With the in-depth research on the application of various energy storage
technologies, energy storage technology is developing rapidly in the direction
of efficient energy conversion, high energy density and low-cost application.
Research and application of megawatt or larger capacity in the China Southern
Power Grid area The energy storage system has very important practical
significance. This article has the following thoughts and suggestions on the
application of energy storage technology in China Southern Power Grid.
4.1 Energy storage price system
The price system is one of the important factors affecting the promotion,
application and development of energy storage technology. Grid companies, power
generation companies, and users all recognize the application prospects of
energy storage technology. However, the current cost of large-capacity energy
storage technology is generally high, the investment per unit capacity is large,
and my country's energy storage-related systems and policies are not perfect.
For the time being, There are no supporting electricity price mechanisms such as
on-grid peak and valley electricity prices, energy storage electricity prices,
and compensation mechanisms. The construction and operation costs of energy
storage stations cannot be channeled in the existing electricity price
system.
Therefore, in order to promote the application and development of energy
storage technology in the China Southern Power Grid region, we should further
promote the establishment and improvement of the price mechanism, promote the
early introduction of peak and valley electricity prices, ladder electricity
prices and energy storage electricity price policies, improve the investment
return mechanism for energy storage technology applications, and encourage All
qualified investors, including power producers, users or third-party independent
energy storage construction companies, invest in the construction of energy
storage devices to promote the positive interactive development of energy
storage station applications and power grid construction.
4.2 Development model
Various large-capacity energy storage technologies have been used in a
large number of actual engineering projects around the world and have been
successfully used in various fields of power systems. There are two main energy
storage technology application and development models that can be used for
reference: the first is to adopt user-side Or the model of investment and
management on the power plant side, in which the power grid company provides
grid connection certification and testing and assessment services, and guides
investors to actively participate in the application and promotion of energy
storage technology by formulating reasonable time-of-use electricity prices and
ladder electricity prices. The second is for the power grid company to directly
participate in the investment and management of energy storage equipment. This
is consistent with the current management method of pumped storage power
stations. The power grid company recovers the investment cost through the energy
storage electricity price. This operating mode is conducive to the unification
of multiple energy storage systems. Scheduling management improves equipment
operation and maintenance levels.
At present, due to the high price of energy storage equipment and many
institutional and policy constraints faced at the macro level, the definition of
investment entities and investment return mechanisms for energy storage
technology applications in my country are not clear. The advantages and
disadvantages of the above two development models The pros and cons, as well as
supporting policies and management mechanisms, require further in-depth analysis
and research.Research.
4.3 Energy storage station demonstration project and energy storage
technology application research
The application of large-capacity energy storage technology in my country
is still in its preliminary stage. Under the premise that the technical
conditions for large-scale promotion and application of energy storage are not
yet mature, consider starting from the energy storage station demonstration
project to research and master the integrated control and grid access technology
of large-capacity energy storage equipment, and accumulate comprehensive
knowledge through pilot projects. technical data, accumulate experience in
energy storage station system planning, equipment selection, engineering
construction and operation and maintenance, and formulate relevant technical
standards and management standards for energy storage systems to be connected to
the power grid. At the same time, relying on the development of pilot work, we
will understand the technical and economic indicators of each link of the energy
storage station project, form an effective technical and economic evaluation
mechanism for energy storage, provide a reference basis for the construction of
energy storage station projects, and ensure that energy storage technology and
related equipment are advanced. The investment and construction meet the goals
of efficiency, economy and practicality.
The smooth development of energy storage station demonstration projects and
energy storage technology application research is not only an important basis
for research on energy storage system access to the power grid, but also an
important basis for formulating technical standards and management requirements
for energy storage systems. It is also an important basis for large-scale
promotion in my country. The prerequisites and guarantees for the application of
energy storage technology provide important engineering practice opportunities
for the development of energy storage technology in my country.
5 Conclusion
At present, the development direction of the entire power industry is to
follow the path of low-carbon economy. The research and application of energy
storage technology is one of the important ways to solve the problem of grid
connection of renewable energy, improve energy utilization efficiency and
improve grid operation efficiency. Moreover, as various energy storage
technologies become increasingly mature, large-capacity energy storage
technology has entered the stage of practical application in power systems.
Therefore, it is of positive and important significance to carry out
comprehensive demonstration projects for the development and application of
energy storage technology in the power system as soon as possible to accumulate
experience for large-scale promotion and application in the future, and to guide
and promote the healthy development of energy storage technology in our
country.
Read recommendations:
703048 1100MAH 3.7V
Is the lithium iron phosphate battery resistant to low temperature?48v 200ah home energy storage bat
Preparation method of Lithium iron phosphate battery.lithium battery 18650
48v 100ah lithium battery pack
803040 battery
360° FACTORY VR TOUR
Whatsapp
Tel
Email
TOP