Pumped storage is the most widely used and mature technology in large-scale energy storage, and the installed capacity of power stations can reach gigawatts. At present, the most mature and largest installed energy storage in the world is pumped hydro.
Pumped storage technology is mature and stable, with high comprehensive benefits, and is often used for peak regulation and backup. Pumped storage is the most widely used and mature technology in large-scale energy storage, and the installed capacity of power stations can reach gigawatts.
According to the incomplete statistics of the Energy Storage Professional Committee of the China Energy Research Association, pumped hydro is currently the most mature and largest installed energy storage in the world. As of 2019, the world’s operational energy storage capacity reached 180 million kilowatts, and the installed capacity of pumped storage energy exceeded 170 million kilowatts, accounting for 94% of the world’s total energy storage.
Pumped-storage power stations use the electricity generated during the low load period of the power system to pump water to a high place for storage, and release water to generate electricity during peak load periods. When the load is low, the pumped storage power station is the user; when the load is peak, it is the power plant.
The pumped storage unit has two basic functions: pumping water and generating electricity. The unit operates as a water turbine when the load of the power system is at its peak. The opening of the guide vane of the water turbine is adjusted through the governor system, and the potential energy of the water is converted into the mechanical energy of the unit rotation, and then the mechanical energy is converted into electrical energy through the generator;
When the load of the power system is low, the water pump is used to pump water from the lower reservoir to the upper reservoir. Through the automatic adjustment of the governor system, the guide vane opening is automatically adjusted according to the pump lift, and the electrical energy is converted into water potential energy and stored. .
Pumped storage power stations are mainly responsible for peak regulation, frequency regulation, emergency backup and black start of the power system, which can improve and balance the load of the power system, improve the power supply quality and economic benefits of the power system, and are the backbone to ensure the safe, economical and stable operation of the power grid. . Pumped-storage power plants are known as “stabilizers”, “regulators” and “balancers” in the safe operation of power grids.
The development trend of the world’s pumped storage power stations is high head, large capacity and high speed. High head means that the unit develops to a higher head, large capacity means that the capacity of a single unit is continuously increasing, and high speed means that the unit adopts a higher specific speed.
Power station structure and characteristics
The main buildings of the pumped storage power station generally include: upper reservoir, lower reservoir, water delivery system, workshop and other special buildings. Compared with conventional hydropower stations, the hydraulic structures of pumped storage power stations have the following main characteristics:
There are upper and lower reservoirs. Compared with conventional hydropower stations with the same installed capacity, the reservoir capacity of pumped-storage power stations is usually relatively small.
The water level of the reservoir fluctuates greatly and rises and falls frequently. In order to undertake the task of peak shaving and valley filling in the power grid, the daily variation of the reservoir water level of the pumped storage power station is usually relatively large, generally exceeding 10-20 meters, and some power stations reach 30-40 meters, and the rate of change of the reservoir water level is relatively fast, generally reaching 5 ~8m/h, and even 8~10m/h.
Reservoir seepage prevention requirements are high. If the pure pumped storage power station causes a large amount of water loss due to the seepage of the upper reservoir, the power generation of the power station will be reduced. At the same time, in order to prevent water seepage from deteriorating hydrogeological conditions in the project area, resulting in seepage damage and concentrated seepage, higher requirements are also placed on reservoir seepage prevention.
The water head is high. The head of the pumped storage power station is generally high, mostly 200-800 meters. The Jixi pumped-storage power station with a total installed capacity of 1.8 million kilowatts is my country’s first 650-meter head section project, and the Dunhua pumped-storage power station with a total installed capacity of 1.4 million kilowatts is my country’s first 700-meter head section project. With the continuous development of pumped storage technology, the number of high-head, large-capacity power stations in my country will increase.
The unit is installed at a low elevation. In order to overcome the influence of buoyancy and seepage on the powerhouse, the large-scale pumped-storage power stations built at home and abroad in recent years mostly adopt the form of underground powerhouses.
The world’s earliest pumped-storage power station is the Netra pumped-storage power station in Zurich, Switzerland, built in 1882. The construction of pumped storage power stations in China started relatively late. The first oblique flow reversible unit was installed in Gangnan Reservoir in 1968. Later, with the rapid development of the domestic energy industry, the installed capacity of nuclear power and thermal power increased rapidly, requiring the power system to be equipped with corresponding pumped storage units.
Since the 1980s, China has begun to vigorously build large-scale pumped-storage power stations. In recent years, with the rapid development of my country’s economy and power industry, my country has achieved fruitful scientific and technological achievements in the equipment autonomy of large-scale pumped storage units.
By the end of 2020, my country’s installed capacity of pumped storage power generation was 31.49 million kilowatts, an increase of 4.0% over the previous year. In 2020, the national pumped-storage power generation capacity was 33.5 billion kWh, an increase of 5.0% over the previous year; the country’s newly added pumped-storage power generation capacity was 1.2 million kWh. my country’s pumped-storage power stations both in production and under construction are ranked first in the world.
State Grid Corporation of China has always attached great importance to the development of pumped storage. At present, State Grid has 22 pumped-storage power stations in operation and 30 pumped-storage power stations under construction.
In 2016, the construction of five pumped-storage power stations in Zhen’an, Shaanxi, Jurong, Jiangsu, Qingyuan, Liaoning, Xiamen, Fujian, and Fukang, Xinjiang started;
In 2017, the construction of six pumped-storage power stations in Yi County of Hebei, Zhirui of Inner Mongolia, Ninghai of Zhejiang, Jinyun of Zhejiang, Luoning of Henan and Pingjiang of Hunan started;
In 2019, the construction of five pumped-storage power stations in Funing in Hebei, Jiaohe in Jilin, Qujiang in Zhejiang, Weifang in Shandong, and Hami in Xinjiang started;
In 2020, four pumped-storage power stations in Shanxi Yuanqu, Shanxi Hunyuan, Zhejiang Pan’an, and Shandong Tai’an Phase II will start construction.
my country’s first pumped storage power station with fully autonomous unit equipment. In October 2011, the power station was successfully completed, indicating that my country has successfully mastered the core technology of pumped storage unit equipment development.
In April 2013, Fujian Xianyou Pumped Storage Power Station was officially put into operation for power generation; in April 2016, Zhejiang Xianju Pumped Storage Power Station with a unit capacity of 375,000 kilowatts was successfully connected to the grid. The autonomous equipment of large-scale pumped storage units in my country has been popularized and applied continuously.
my country’s first 700-meter head pumped-storage power station. The total installed capacity is 1.4 million kilowatts. On June 4, 2021, Unit 1 was put into operation to generate electricity.
The pumped-storage power station with the largest installed capacity in the world is currently under construction. The total installed capacity is 3.6 million kilowatts.
Pumped storage has the characteristics of basic, comprehensive and public. It can participate in the regulation services of the new power system source, network, load and storage links, and the comprehensive benefits are more significant. It carries the power system safe power supply stabilizer, clean low-carbon balancer and high efficiency Important function of the running regulator.
The first is to effectively deal with the lack of reliable reserve capacity of the power system under the penetration of high proportion of new energy. With the advantage of double capacity peak regulation, we can improve the large-capacity peak regulation capacity of the power system, and alleviate the peak load supply problem caused by the instability of new energy and the peak load caused by the trough. The consumption difficulties caused by the large-scale development of new energy during the period can better promote the consumption of new energy.
The second is to effectively deal with the mismatch between the output characteristics of new energy and the load demand, relying on the flexible adjustment ability of rapid response, to better adapt to the randomness and volatility of new energy, and to meet the flexible adjustment demand brought by new energy “depending on the weather”.
The third is to effectively deal with the insufficient moment of inertia of the high-proportion new energy power system. With the advantage of the high moment of inertia of the synchronous generator, it can effectively enhance the anti-disturbance capability of the system and maintain the system frequency stability.
The fourth is to effectively deal with the potential safety impact of the “double-high” form on the new power system, assume the emergency backup function, and respond to sudden adjustment needs at any time with fast start-stop and fast power ramping capabilities. At the same time, as an interruptible load, it can safely remove the rated load of the pumping unit with millisecond response, and improve the safe and stable operation of the system.
The fifth is to effectively deal with the high adjustment costs brought by large-scale new energy grid connection. Through reasonable operation methods, combined with thermal power to reduce carbon and increase efficiency, reduce the abandonment of wind and light, promote capacity allocation, and improve the overall economy and clean operation of the entire system.
Strengthen the optimization and integration of infrastructure resources, coordinate the safety, quality and progress management of 30 projects under construction, vigorously promote mechanized construction, intelligent control and standardized construction, optimize the construction period, and ensure that the pumped storage capacity will exceed 20 million during the “14th Five-Year Plan” period. kilowatts, and the operating installed capacity will exceed 70 million kilowatts by 2030.
The second is to work hard on lean management. Strengthening planning guidance, centering on the “dual carbon” goal and the implementation of the company’s strategy, high-quality preparation of the “14th Five-Year” development plan for pumped storage. Scientifically optimize the preliminary work procedures of the project, and advance the project feasibility study and approval in an orderly manner. Focusing on safety, quality, construction period, and cost, vigorously promote intelligent management and control, mechanized construction and green construction of engineering construction to ensure that projects under construction can achieve benefits as soon as possible.
Deepen the life cycle management of equipment, deepen the research on the power grid service of units, optimize the operation strategy of units, and fully serve the safe and stable operation of the power grid. Deepen multi-dimensional lean management, speed up the construction of a modern smart supply chain, improve the material management system, scientifically allocate capital, resources, technology, data and other production factors, vigorously improve quality and efficiency, and comprehensively improve management efficiency and operating efficiency.
The third is to seek breakthroughs in technological innovation. In-depth implementation of the “New Leap Forward Action Plan” for scientific and technological innovation, increase investment in scientific research, and improve the ability of independent innovation. Increase the application of variable speed unit technology, strengthen the technology research and development of 400-megawatt large-capacity units, speed up the construction of pump-turbine model laboratories and simulation laboratories, and make every effort to build an independent scientific and technological innovation platform.
Optimize the scientific research layout and resource allocation, strengthen the research on the core technology of pumped storage, and strive to overcome the technical problem of “stuck neck”. Deepen the research on the application of new technologies such as the “Big Cloud IoT Smart Chain”, comprehensively deploy the construction of digital intelligent power stations, and accelerate the digital transformation of enterprises.
Post time: Mar-07-2022
