Re-understanding of the development of pumped-storage power stations

At present, with the large-scale development of new energy sources, access to distributed generation, and the cancellation of national approvals for large-scale direct-purchased electricity pilots, the demand for reliable and intelligent power grids is increasing, and the demand for pumped storage from power systems is increasing. increase. In June this year, the “Notice of the State Administration of Energy on Strengthening the Operation and Management of Pumped-storage Power Stations” (Guo Nengxineng [2013] No. 243) put forward higher requirements for the utilization of pumped-storage power in China under the new situation.

The mature and practical large-scale electric energy storage method pumped storage power station is a kind of power generation method with energy storage function, which combines the characteristics of power generation and energy storage. In the 1950s, Western European countries led the world in the development of pumped storage power stations. The installed capacity of pumped-storage power stations in Western Europe accounted for 35% to 40% of the total installed capacity of pumped-storage power stations in the world. By the late 1960s, the installed capacity of pumped-storage power stations in the United States ranked first in the world. After entering the 1990s, Japan came from behind and surpassed the United States as the country with the largest installed capacity of pumped-storage power stations.

As of the end of 2012, there are 34 pumped-storage power stations in China. Among them, 26 were put into operation, capacity for operation was 20.645 million kilowatts, 8 were under construction, capacity was under construction at 8.94 million kilowatts, and total installed capacity was 29.955 million kilowatts, accounting for 1.7% of the country's total installed capacity.

The reasonable scale of pumped storage in the power system is related to a variety of factors such as power supply structure, grid structure, and load characteristics of the power system. In 2009, the United Kingdom, the United States, Japan, and other countries accounted for 3.55%, 2.22%, and 10.7% of their domestic installed capacity, respectively, when gas-fired generating units accounted for a large proportion of domestic installed capacity. Pumped storage in developed countries accounts for 3% to 10% of the total installed capacity of the system. Compared with the developed countries in the world, China's pumped-storage capacity is obviously insufficient, and it is far from meeting the needs of China's rapid economic and social development and the need for coal-based power systems to operate safely and stably. It is unable to meet the needs of energy-saving and emission-reducing power systems, and large-scale clean energy sources. Long-distance transmission, large-scale access to distributed generation, and the need for intelligent grid construction.

Compared with conventional power generation methods, pumped storage cannot use primary energy to generate electricity, it cannot increase the power supply of the power system, and it has the energy storage function that other power generation methods do not have. Among all power generation methods, only the peak speeds of conventional hydropower and single-cycle gas turbines can be compared with pumped storage, but due to resource constraints, conventional hydropower resources have been exhausted; single-cycle gas turbines have higher gas prices and peaking costs Larger, and affected by temperature changes in the throughflow section, it is not possible to start and stop frequent peaking like pumped storage. For example, the Pushihe pumped storage power station has 1,900 units in the first half of 2013, generating 1,080 power generation operations, 786 pumping operations, and 175 pumping operations. Pumped storage has the largest maximum peaking capacity and is the fastest to start uploading. It is the only power source with a valley filling function. Pumped storage is the most flexible power generation mode among various power sources.

At present, except for pumped storage, large-scale energy storage devices only have compressed air energy storage and some chemical battery energy storage devices. The large-scale compressed air energy storage requires strict requirements on the geological conditions and tightness of the underground caverns. At the same time, it requires the gas turbines to operate in cooperation with them. It is in a demonstration operation stage in foreign countries and there are no practical examples in China. Chemical energy storage has the problems of long time of charge and discharge, rapid efficiency decay, high unit investment, high operating environment, waste battery electrolyte, and large environmental pollution, and the current batch production capacity is limited. The unit kilowatts cost of each chemical energy storage battery is 25,000 yuan/kW for liquid flow batteries, 28,000 yuan/kW for sodium-sulfur batteries, and 10,000 yuan/kW for lithium batteries. The life cycle is related to the number of charge and discharge times, generally not more than 15 years; during the work process, there is a high requirement for the ambient temperature and air conditioning must be used to reduce the temperature.

Compared with these energy storage devices, the pumped-storage power station has a low investment of 3,000 to 5,000 yuan per kilowatt; the service life is long, the service life of the unit is 25 years, the service life of the hydraulic structure is more than a hundred years, and the energy conversion efficiency is stable. There is an attenuation problem and it has a small impact on the environment. Therefore, pumped storage is the most mature and practical large-scale energy storage method in the current power system.

Pumped storage power station peaking and filling the valley has a significant role in coal saving. First, it reduces the number of thermal power generators participating in the peak load start-stop, increases the thermal power unit load rate, and operates in an efficient area, reducing the unit's fuel consumption. Second, in the case of economic dispatch, low valley power is sent from the base load unit with the lowest coal consumption in the system, and peak power is sent from the peak load unit with the highest coal consumption in the system. Pumped-storage power stations use electricity from high-efficiency, low-coal-fired units to replace electricity generated by low-efficiency, high-coal-fired units, thereby realizing effective energy-saving and emission reduction of the power system.

China's power system installed mainly coal-fired power. The peak shaving amplitude of the coal-fired power unit is relatively small and the peak shaving capacity is relatively poor. Although it can meet the normal operation requirements of the system, it is far from being able to guarantee the quick adjustment requirements in the event of a power system accident. The pumped-storage power station is characterized by its ability to adapt to rapid changes in load. It usually takes only 2 to 3 minutes from pumping conditions to full-load operation, allowing quick and wide-range adjustment of output.

Pumped storage power stations play an important role in improving the level of safe and stable operation of the power system and ensuring the quality of power supply. First, the pumped-storage power station has flexible start and stop and rapid response. It has good dynamic performance in emergency backup and black start tasks in the power system, which can effectively improve the level of safe and stable operation of the power system. Second, the pumped storage power station tracks the load. Rapidly adapting to rapid changes in load is a flexible and reliable power source for regulating the frequency and voltage stability in the power system. It can effectively ensure and improve the operating frequency and voltage stability of the power grid, and better meet the power supply quality of customers. The higher requirements of reliability; Third, pumped-storage power stations use their peak-peaking and valley-filling performance to reduce system peak-to-valley differences, improve the smoothness of power grid operation, effectively reduce the number of grid power cuts, and reduce the number of enterprises and residents. Power customers' production and living influences.

At the same time, pumped-storage power stations can cope with the large-scale development of wind power and other renewable energy sources, and improve the power system's ability to absorb renewable energy such as wind power. The geographical distribution of new energy resources and energy demand in China is very different. New sources of energy such as wind power and photovoltaic power generation are far away from the load center and must be transported at large distances. Wind power is affected by changes in the local wind power, the electrode is unstable, and the impact on the system is very large.

The construction of a power-system pumped-storage power station of an appropriate scale can give full play to the complementarity between pumped-storage power storage and wind power operation. The use of pumped-storage power stations can balance wind power and solar power output, reduce randomness and volatility, and improve transmission lines. The economical nature can also balance the imbalance of wind power generation, participate in frequency modulation of power grid operation, reduce the impact of wind power on the power grid, and solve the practical problems of current wind power transmission difficulties.

In addition, the pumped-storage power station can also cooperate with the large-scale development of nuclear power to reduce system peaking and frequency modulation pressure. Nuclear power is suitable for long-term stable base-load operation, and the large-scale development of nuclear power will bring great pressure to the peaking of power systems based on coal-fired power systems. The construction of an appropriate scale pumped storage power station and nuclear power operation can solve the problem of peak shaving during the operation of nuclear power base load, and improve the operational efficiency and safety of nuclear power plants. The adjustment of the Guangzhou Pumped Storage Power Station to the Daya Bay Nuclear Power Station is a successful example of the current cooperation between China's pumped storage power and nuclear power.

Pumped storage is still an important means for ensuring the safety of large power grids by improving the level of intelligence in the power grid and responding to direct purchases by large users and access to distributed generation. After the country cancels the large-scale direct purchase pilot approval, the scale and scope of direct purchase pilots may expand, and higher requirements will be placed on the management mode, operation mode, and technical support system of the power grid. With the development of distributed generation, the low-voltage power grid has changed from passive to active and the operation of the power grid has become more complex. The level of intelligence, safety and stability of the power grid have been further enhanced.

In the aspects of power generation, supply and use of the power grid, the optimal allocation of pumped storage power stations of appropriate scale can give full play to the unique rapid response characteristics of pumped storage power stations and effectively prevent the risk of failure of the power grid. Pumped storage is a reliable guarantee for highly intelligent grid dispatching and is an important organic component of a strong smart grid construction. For the construction of strong smart grids, it is imperative to configure different pumping storage capacities with different regulation performances and sizes to meet the new needs of the power system at different voltage levels, different grid structures, and different stages of transmission and distribution.

The future development of China's pumped-storage power is affected by the level of awareness. While China's pumped-storage capacity has made great achievements, there are also some institutional and institutional problems. Since entering the new century, especially after the National Energy Administration Pumped Storage Power Station work conference in 2009, the parties have gradually realized the understanding of pumped storage, the planning and layout optimization research of pumping and storage sites throughout the country, pumped storage planning, Professional personnel training and experience accumulation have laid a solid foundation for the development of pumped storage in China. In the future, the development of pumped storage in China will focus on the following aspects.

First, the understanding of the role of pumped storage in energy saving and emission reduction, smart grid construction, and power supply structure adjustment is further unified. With the continuous improvement of energy-saving and emission-reduction requirements in China, the adjustment of industrial structure and energy structure is gradually accelerating, electricity consumption of high-energy-consuming enterprises is gradually decreasing, the peak-to-valley difference of the power system is increasing, and large-scale development of clean energy such as wind power and nuclear power, etc. The rapid development of large-scale direct-purchased power and distributed power supplies places higher demands on the safety and intelligence of power grids. A strong smart grid will become the common choice of the whole society, and people will pump and store energy in energy-saving emission reduction and smart grids. The understanding of the important role of development will be widely and highly unified. Pumped storage is the inevitable choice for China to achieve energy-saving, emission reduction, cleanliness and intelligent development of the power system.

Second, according to the characteristics of the power system in each region and province, determine the functional positioning and actively guide the effectiveness of each pumped-storage power station. Affected by primary energy and economic and social development, the power supply structure and load characteristics of power systems in various regions and provinces in China are quite different. The proportion of hydropower in Sichuan, Hunan, Hubei and other places is relatively large. In Shandong and Hebei, mainly in thermal power, wind power in Gansu, Xinjiang, Inner Mongolia and other provinces is developing rapidly. Zhejiang and other coastal provinces accept large-scale calls outside the region...

Due to the differences in power systems, pumped storage power stations in different provinces have different functions, some of which are based on energy storage, such as Gansu and Xinjiang; others are mainly based on accidents, such as Shandong and Shanxi; some Main peaks and valleys are filled, such as the three northeastern provinces and the east China coast. The “Notice of the National Energy Administration on Strengthening the Operation and Management of Pumped-storage Power Stations” calls for the establishment of a sound monitoring and supervision system for pumped storage, strengthening the analysis of the operating conditions and utilization status of the already-built storage power stations, and researching and perfecting the management mechanism for pumped-storage power stations. Measures. This requires the use of the power system as the boundary of analysis, combining the characteristics of the power system and the operating characteristics, taking into account the functional positioning of the pumped-storage power station in the corresponding power system, and the regional and time-scale features of the pumped-storage power station, objectively and comprehensively. Evaluate the operational benefits of pumped-storage power stations and actively guide the comprehensive benefits of pumped-storage power stations.

Third, the state’s policy environment for pumped storage is constantly improving and guiding investment in pumped storage. Due to the huge role of pumped storage in the power system, the government will gradually improve the pumped storage policy environment, set about solving the various problems affecting the development of pumped storage, giving reasonable investment returns for pumped storage, and guiding the enthusiasm of pumped storage development. As China's power supply structure is dominated by coal-fired power, coal-fired power generation and peak shaving cannot meet the needs of large-scale development of wind power and nuclear power. Pumped storage energy is used to solve the problems affecting the large-scale development of wind power, and the large-scale grid-connected power generation brings about peak shaving. The pressure to improve the flexibility and safety of smart grid operation plays an important role. The country is likely to improve relevant policies, increase the rate of return on investment in pumped storage, and guide more investment in pumped storage.

Fourth, the pumped storage capacity is optimally configured according to capacity and positioning in different voltage levels, and it is in harmony with other various energy storage devices to promote the intelligent development of the power system. As an important adjustment tool, pumped storage is an integral part of the smart grid. Smart grid construction provides a rare opportunity for the development of pumped storage. In order to maximize the safety and stability of the smart grid and the flexibility of the power supply, the pumped storage will be positioned according to the installed capacity and its role in the system, and priority will be given to the planning and construction of large-capacity pumped storage power stations with significant influence. The smaller-capacity pumped-storage power stations perform fine adjustment of local or even distribution networks, so that different pumped-storage power options can be connected to different voltage-grade power systems to achieve a hierarchically optimized configuration. The installed capacity and regulation performance of pumped-storage systems will be further improved. Reasonable, to achieve a reasonable distribution of the power system, transmission, distribution, use, and give full play to its role in the power system. Pumped storage has developed in tandem with small energy storage devices such as flywheel energy storage, capacitors, and electric vehicle batteries to achieve highly intelligent power system development and greatly improve the quality of power supply.

Considering the large-scale development of wind power, photovoltaic power generation and nuclear power in China, the proportion of pumped-storage power in China's power system will gradually increase in the future, and the reasonable scale should reach more than 5% of the total installed capacity. In 2020, the reasonable scale of pumped storage in China is expected to reach 80 million kilowatts; in 2030, the reasonable scale of pumped storage in China is expected to reach 120 to 140 million kilowatts.

Fifth, the model of pumped-storage group operation, intensive development, and professional management will be further strengthened. Pumped-storage energy storage is different from general power generation methods. It is an adjustment tool for the power system. Its installed capacity, layout optimization, and its role are closely related to the power system's power supply structure, load characteristics, and network structure. The development plan for pumped-storage power must be carefully studied from the overall needs of the power system. Blind competition is not conducive to the exertion of its role and the development of the industry.

At present, the State Grid Corporation of China and China Southern Power Grid Corporation adopt the mode of group operation, intensive development, and professional management to achieve a close combination of pumped-storage site selection, layout optimization, and meeting the needs of the grid, summarizing the experience of operating the plant, and optimizing the new The development of power plant design has promoted the effective exchange of operating modes, technological innovations, and management experience among pumped storage power stations, and has played an important role in promoting the sound and sustainable development of pumped storage in China. It has become the backbone of the development of pumped storage in China. power. Therefore, with the further improvement of the understanding of pumped storage, the model of pumping and storage group operation, intensive development, and professional management will only be strengthened and will not be weakened. The development of pumped-storage development based on local and local interests will be further restricted.