I have a friend who is in his prime of life and is very healthy. Although I haven’t heard from you for many days, it is expected to be all right. This day I met him by chance, but he looked very haggard. I couldn’t help worrying about him. I went forward to ask for details.
He sighed and said slowly, “I have a crush on a girl recently.”. It can be said that “beautiful smiles and beautiful eyes” move my heartstrings. However, the parents at home are still in the classroom and have doubts, so they haven’t been hired for a long time. “My belt is getting wider and I will not regret it, and I will be emaciated for Iraq”, which makes me feel like this today. I always know that you have a lot of knowledge. Now that you are destined to meet today, I would like to ask you to help the staff. If fate is determined by nature, since the Six Rites have been met, the two surnames will marry and make a contract in one house. The good relationship will never end, matching the same name. With the promise of white head, write to Hongjian, so that the alliance of red leaves can be recorded in the mandarin tree. If there is any disharmony, we should also “solve the grievance and release the knot, let alone hate each other; one parting and the other forgiving, and each one is happy.” By the way, this girl has a double name for pumping water and a double name for energy storage.
After listening to this, I am not angry at all. It is clearly your leader who asked you to judge whether the pumped storage power station has investment value, but you said it was so fresh and refined. “A good marriage is made by nature, and a good couple is made by nature”. I can’t say anything about feelings. But when it comes to pumped-storage power stations, I just asked a senior senior person about the evaluation system of “five-dimensional integration” after the construction practice of more than 100 pumped-storage projects. They are geographical location, construction conditions, external conditions, engineering design and economic indicators. If you want to, just listen to me for you.
1、 Geographic location
There is an old saying in the real estate industry that “location, location, location” is “location, location, or location”. This famous Wall Street saying was widely spread after being quoted by Li Ka-shing.
In the comprehensive evaluation of pumped storage projects, geographical location is also the first. The function orientation of pumped storage mainly serves the power grid or the development of large new energy bases. Therefore, the geographical location of the pumped storage power station is mainly two points: one is close to the load center, and the other is close to the new energy base.
At present, most of the pumped-storage power stations that have been built or are under construction in China are located in the load center of the grid where they are located. For example, Guangzhou pumped-storage power station (2.4 million kilowatts) is 90 kilometers away from Guangzhou, the Ming Tombs pumped-storage power station (0.8 million kilowatts) is 40 kilometers away from Beijing, Tianhuangping pumped-storage power station (1.8 million kilowatts) is 57 kilometers away from Hangzhou, and Shenzhen pumped-storage power station (1.2 million kilowatts) is located in the urban area of Shenzhen.
In addition, in order to meet the needs of rapid development of new energy, around the integrated development of water and scenery and the development of new energy base in the desert and Gobi desert, a new batch of pumped storage power stations can also be planned near the new energy base. For example, the pumped-storage power stations currently planned in Xinjiang, Gansu, Shaanxi, Inner Mongolia, Shanxi and other places, in addition to meeting the needs of the local power grid, are mainly for new energy base services.
So the first point of comprehensive evaluation of pumped storage power station is to see where she was born first. In general, pumped storage should follow the principle of decentralized distribution, focusing on the distribution near the grid load center and the new energy concentration area. In addition, for areas without pumped storage stations, priority should also be given when there are good resource conditions.
2、 Construction conditions
1. Topographic conditions
The analysis of topographic conditions mainly includes water head, distance to height ratio, and natural effective storage capacity of upper and lower reservoirs. The energy stored in pumped storage is essentially the gravitational potential energy of water, equal to the product of the height difference and the gravity of water in the reservoir. So in order to store the same energy, either increase the height difference between the upper and lower reservoirs, or increase the regulated storage capacity of the pumped storage upper and lower reservoirs.
If conditions are met, it is more appropriate to have a larger height difference between the upper and lower reservoirs, which can reduce the size of the upper and lower reservoirs and the size of the plant and electromechanical equipment, and reduce the project investment. However, according to the current manufacturing level of pumped-storage units, too large a height difference will also lead to greater difficulty in unit manufacturing, so the bigger the better. According to engineering experience, the general drop is between 400 and 700m. For example, the rated head of the Ming Tombs Pumped Storage Power Station is 430m; The rated head of Xianju Pumped Storage Power Station is 447m; The rated head of Tianchi Pumped Storage Power Station is 510m; The rated head of Tianhuangping Pumped Storage Power Station is 526m; The rated head of Xilongchi Pumped Storage Power Station is 640m; The rated head of Dunhua Pumped Storage Power Station is 655m. At present, Changlongshan Pumped Storage Power Station has the highest utilization head of 710m, which has been built in China; The highest utilization head of the pumped storage power station under construction is Tiantai pumped storage power station, with a rated head of 724m.
Space-depth ratio is the ratio between the horizontal distance and the elevation difference between the upper and lower reservoirs. Generally speaking, it is appropriate to be smaller, which can reduce the engineering quantity of the water conveyance system and save the engineering investment. However, according to the engineering experience, too small spacing to height ratio can easily cause problems such as engineering layout and high and steep slopes, so it is generally appropriate to have a spacing to height ratio between 2 and 10. For example, the distance to height ratio of Changlongshan pumped storage station is 3.1; The distance to height ratio of Huizhou pumped storage station is 8.3.
When the terrain of the upper and lower reservoir basins is relatively open, the need for energy storage can be formed within a small area of the reservoir basin. Otherwise, it is necessary to expand the area of the reservoir basin or to adjust the reservoir capacity through expansion and excavation, and increase the land occupation and engineering quantity. For pumped-storage power stations with installed capacity of 1.2 million kilowatts and full utilization hours of 6 hours, the storage capacity for power generation regulation needs about 8 million m3, 7 million m3 and 6 million m3 respectively when the water head is 400m, 500m and 600m. On this basis, it is also necessary to consider dead storage capacity, water loss reserve storage capacity and other factors to finally determine the total storage capacity of the reservoir. In order to meet the reservoir capacity requirements, it needs to be formed by damming or expanding excavation in the reservoir in combination with the natural terrain.
In addition, the catchment area of the upper reservoir is generally small, and the flood control of the project can be solved by appropriately increasing the dam height. Therefore, the narrow valley at the outlet of the upper reservoir basin is an ideal place for dam construction, which can significantly reduce the amount of dam filling.
2. Geological conditions
Only the green mountains are like walls when they point to the Six Dynasties.
——Yuan Sadurah
The geological conditions mainly include the regional structural stability, the engineering geological conditions of the upper and lower reservoirs and their junction areas, the engineering geological conditions of the water transmission and power generation system, and the natural building materials.
The retaining and discharge structures of the pumped storage power station should avoid active faults, and the reservoir area should not have large landslides, collapses, debris flows and other adverse geological phenomena. The underground powerhouse caverns should avoid weak or broken rock masses. When these conditions cannot be avoided through the engineering layout, the geological conditions will restrict the construction of the pumped storage power station.
Even if the pumped storage power station avoids the above constraints, the geological conditions also greatly affect the project cost. Generally speaking, the rarer the earthquake in the project area and the harder the rock, the more conducive to reducing the construction cost of pumped storage power stations.
According to the characteristics of the buildings and the operation characteristics of the pumped storage power station, the main engineering geological problems can be summarized as follows:
(1) Compared with conventional power stations, there is more room for comparison and selection of the station site and reservoir site of pumped storage power stations. Sites with poor geological conditions or difficult engineering treatment can be screened out through the geological work at the station site survey and station planning stage. The role of geological exploration is particularly important at this stage.
However, the wonders and wonders of the world often lie in the danger and distance, and what is the rarest of people, so it is impossible for anyone who has a will to reach it.
——Song Dynasty, Wang Anshi
Survey of Upper Dam Site of Shitai Pumped Storage Power Station in Anhui Province
(2) There are many underground engineering caverns, long high pressure tunnel sections, large internal water pressure, deep burial and large scale. It is necessary to fully demonstrate the stability of surrounding rock, and determine the excavation method, support and lining type, scope and depth of tunnel surrounding rock.
(3) The storage capacity of the pumped storage reservoir is generally small, and the pumping cost is high during the operation period, so the leakage amount of the upper reservoir needs to be strictly controlled. The upper reservoir is mostly located at the top of the mountain, and there are generally low adjacent valleys around it. A considerable number of stations are selected in areas with negative karst landforms in order to take advantage of the advantageous terrain. The problems of reservoir adjacent valley leakage and karst leakage are relatively common, which need to be focused on and the construction quality should be well controlled.
(4) The distribution of the materials used for dam filling in the reservoir basin of the pumped storage power station is the key factor to determine the utilization rate of the material source. When the reserves of the materials used in the excavation area of the reservoir basin above the dead water level just meet the dam filling requirements and there is no surface stripping material, the ideal state of the material source excavation and filling balance is reached. When the surface stripping material is thick, the problem of using the stripping material on the dam can be solved by dividing the dam material. Therefore, it is very important to establish a relatively accurate geological model of the upper and lower reservoirs through effective exploration means for the design of the excavation and filling balance of the reservoir basin.
(5) During the operation of the reservoir, the sudden rise and fall of the water level are frequent and large, and the operation mode of the pumped storage power station has a great impact on the stability of the reservoir bank slope, which puts forward higher requirements for the geological conditions of the reservoir bank slope. When the requirements for the stability safety factor are not met, it is necessary to slow down the excavation slope ratio or increase the support strength, resulting in increased engineering costs.
(6) The foundation of the whole anti-seepage reservoir basin of the pumped storage power station has high requirements for deformation, drainage and uniformity, especially for the foundation of the whole anti-seepage reservoir basin in karst areas, karst collapse at the bottom of the reservoir, uneven deformation of the foundation, reverse jacking of karst water, karst negative pressure, collapse of the overburden of karst depression, and other issues need to be paid enough attention.
(7) Due to the large elevation difference of the pumped storage power station, the reversible unit has higher requirements for the control of the sediment content passing through the turbine. It is necessary to pay attention to the protection and drainage treatment of the solid source of the gully at the rear edge of the slope at the inlet and outlet and the storage of the flood season sediments.
(8) Pumped-storage power stations will not form high dams and large reservoirs. The dam height and manually excavated slopes of most of the upper and lower reservoirs are not more than 150m. The engineering geological problems of the dam foundation and high slopes are less difficult to deal with than the high dams and large reservoirs of conventional power stations.
3. Warehouse forming conditions
The upper and lower reservoirs should have the terrain conditions suitable for damming. Generally speaking, the utilization head of about 400~500m is considered based on the installed capacity of 1.2 million kilowatts and the utilization hours of full power generation of 6 hours, that is, the regulated storage capacity of the pumped storage upper and lower water reservoirs is about 6 million~8 million m3. Some pumped-storage stations naturally have a “belly”. It is easy to form the reservoir capacity through damming. In this case, it can be impounded through damming. However, some pumped-storage stations have small natural storage capacity and need to be excavated to form the storage capacity. This will bring two problems, one is the relatively high development cost, the other is that the storage capacity needs to be excavated in large quantities, and the energy storage capacity of the power station should not be too large.
In addition to the storage capacity requirements, the pumped storage reservoir project should also consider the reservoir seepage prevention, earth and rock excavation and filling balance, dam type selection, etc., and determine the design scheme through comprehensive technical and economic comparison. Generally speaking, if a reservoir can be formed by damming, and local seepage prevention is adopted, the conditions for reservoir formation are relatively good (see Fig. 2.3-1); If a “basin” is formed by a large amount of excavation, and the whole basin anti-seepage type is adopted, the conditions for reservoir formation are relatively general (see Fig. 2.3-2 and 2.3-3).
Taking Guangzhou pumped storage power station with good reservoir forming conditions as an example, the upper and lower reservoir forming conditions are relatively good, and the reservoir can be formed by damming, with the upper reservoir capacity of 24.08 million m3 and the lower reservoir capacity of 23.42 million m3.
In addition, Tianhuangping pumped storage power station is taken as an example. The upper reservoir is located in the gully source depression of the branch ditch on the left bank of the Daxi River, which is surrounded by the main dam, four auxiliary dams, inlet/outlet and the mountains around the reservoir. The main dam is arranged in the depression at the south end of the reservoir, and the auxiliary dam is arranged in the four passes in the east, north, west and southwest. The storage conditions are medium, with a total storage capacity of 9.12 million m3.
4. Water source conditions
Pumped storage power stations are different from conventional hydropower stations, that is, a “basin” of clear water is poured back and forth between the upper and lower reservoirs. When pumping water, the water is poured from the lower reservoir to the upper reservoir, and when generating electricity, the water is lowered from the upper reservoir to the lower reservoir. Therefore, the water source problem of the pumped storage power station is mainly to meet the initial water storage, that is, to store the water in the reservoir first, and to supplement the water volume reduced due to evaporation and leakage during daily operation. The pumped storage capacity is generally in the order of 10 million m3, and the requirements for water volume are not high. Water source conditions in areas with large rainfall and dense river networks will not be the limiting conditions for the construction of pumped storage power stations. However, for the relatively arid regions such as the northwest, the water source condition has become an important constraint factor. Some places have the topographical and geological conditions for the construction of pumped storage, but there may be no water source for water storage for tens of kilometers.
3、 External conditions
The essence of immigration and environmental issues is to deal with the issue of public resource occupation and compensation. It is a win-win and multi-win process.
1. Land acquisition and resettlement for construction
The scope of land acquisition for the construction of pumped storage power station includes the upper and lower reservoir inundation area and the hydroproject construction area. Although there are two reservoirs in the pumped storage power station, because the reservoirs are relatively small, some of them use natural lakes or existing reservoirs, the scope of land acquisition for construction is often far smaller than that for conventional hydropower stations; Because most of the reservoir basins are excavated, the construction area of the hydroproject often includes the reservoir inundation area, so the proportion of the hydroproject construction area in the land acquisition scope of the project construction is far greater than that of the conventional hydropower station.
The reservoir inundation area mainly includes the inundation area below the normal pool level of the reservoir, as well as the flood backwater area and the reservoir affected area.
The hydroproject construction area mainly includes the hydroproject buildings and the project permanent management area. The construction area of the hub project is determined as the temporary area and the permanent area according to the purpose of each plot. The temporary land can be restored to its original use after use.
The scope of land acquisition for construction has been determined, and the important follow-up work is to carry out the investigation of the physical indicators of land acquisition for construction, so as to “know yourself and know the other”. It is mainly to investigate the quantity, quality, ownership and other attributes of the population, land, buildings, structures, cultural relics and historic sites, mineral deposits, etc. within the scope of land acquisition for construction.
For decision-making, the main concern is whether the land acquisition for construction involves major sensitive factors, such as the scale and quantity of permanent basic farmland, first-class public welfare forest, important villages and towns, major cultural relics and historic sites, and mineral deposits.
2. Ecological environment protection
The construction of pumped storage power stations must adhere to the principle of “ecological priority and green development”.
Avoiding environmentally sensitive areas is an important prerequisite for the feasibility of the project. Environmentally sensitive areas refer to all kinds of protection areas at all levels established according to law and areas that are particularly sensitive to the environmental impact of the construction project. When selecting sites, environmental sensitive areas should be screened and avoided first, mainly including ecological protection red lines, national parks, natural reserves, scenic spots, world cultural and natural heritage sites, drinking water source protection areas, forest parks, geological parks, wetland parks Aquatic germplasm resources protection zone, etc. In addition, it is also necessary to analyze the compliance and coordination between the site and relevant planning such as land space, urban and rural construction, and “three lines and one single”.
Environmental protection measures are important measures to reduce environmental impact. If the project does not involve environmentally sensitive areas, it is basically feasible from the perspective of environmental protection, but the construction of the project will inevitably have a certain impact on the water, gas, sound and ecological environment, and a series of targeted measures need to be taken to eliminate or mitigate the adverse effects, such as the treatment of production wastewater and domestic sewage, and the discharge of ecological flow.
Landscape building is an important way to achieve high-quality development of pumping and storage. Pumping and storage power stations are generally located in mountainous and hilly areas with good ecological environment. After the completion of the project, two reservoirs will be formed. After ecological restoration and landscape construction, they can be included in scenic spots or tourist attractions to achieve the harmonious development of the power station and the environment. The implementation of the concept of “green water and green mountains is golden mountains and silver mountains”. For example, Zhejiang Changlongshan Pumped Storage Power Station has been included in the core scenic spot of Tianhuangping Provincial Scenic Spot – Jiangnan Tianchi, and Qujiang Pumped Storage Power Station has been included in the third level protection zone of Lankeshan-Wuxijiang Provincial Scenic Spot.
4、 Engineering design
The engineering design of pumped storage power station mainly includes project scale, hydraulic structures, construction organization design, electromechanical and metal structures, etc.
1. Project scale
The engineering scale of the pumped storage power station mainly includes the installed capacity, the number of continuous full hours, the main characteristic water level of the reservoir and other parameters.
The selection of the installed capacity and the number of continuous full hours of the pumped storage power station should take into account both the need and the possibility. Need refers to the demand of the power system, and may refer to the construction conditions of the power station itself. The general method is based on the analysis of the functional positioning of different power systems for pumped-storage power stations and the requirements of the power system for the number of continuous full hours, to reasonably draw up the installed capacity plan and the number of continuous full hours, and to select the installed capacity and the number of continuous full hours through the power production simulation and comprehensive technical and economic comparison.
In practice, a simple method to initially plan the installed capacity and full utilization hours is to first determine the unit capacity according to the water head range, and then determine the total installed capacity and full utilization hours according to the natural storage energy of pumped storage. At present, in the range of 300m~500m water level drop, the design and manufacturing technology of the unit with the rated capacity of 300000 kilowatts is mature, the stable operation conditions are good, and the engineering practice experience is the richest (this is why the installed capacity of most of the pumped-storage power stations under construction is generally an even number of 300000 kilowatts, taking into account the requirements of decentralized layout, and finally the majority is 1.2 million kilowatts). After the unit capacity is initially selected, the natural energy storage of the pumped storage power station is analyzed based on the topographical and geological conditions of the upper and lower reservoirs, and the head loss of the power generation and pumping conditions. For example, through preliminary analysis, if the average water level drop between the upper and lower reservoirs of a pumped storage power station is about 450m, it is appropriate to select 300000 kilowatts of unit capacity; The natural storage energy of the upper and lower reservoirs is about 6.6 million kilowatt-hours, so four units can be considered, that is, the total installed capacity is 1.2 million kilowatts; Combined with the demand of the power system, after some expansion and excavation of the reservoir based on the natural conditions, the total energy storage will reach 7.2 million kilowatt-hours, corresponding to the continuous full power generation hours of 6 hours.
The characteristic water level of the reservoir mainly includes the normal water level, dead water level and flood level. Generally, the characteristic water level of these reservoirs is selected after the number of continuous full hours and installed capacity are selected.
2. Hydraulic structures
In front of us is the rolling river, and behind us is the brilliant lights. This is how our life is, fighting and running forward.
——Song of Water Conservancy Builders
Hydraulic structures for pumped storage generally include upper reservoir, lower reservoir, water conveyance system, underground powerhouse and switch station. The key point of the design of the upper and lower water reservoirs is to obtain large storage capacity through the minimum engineering cost. Most of the upper reservoirs adopt the combination of excavation and damming, and most of them are face rockfill dams. According to the geological conditions, the reservoir leakage of the pumped storage power station can be solved by means of the whole reservoir seepage prevention and the curtain seepage prevention around the reservoir. The seepage prevention materials can be asphalt concrete face plate, geomembrane, clay blanket, etc.
Schematic diagram of pumped storage power station
When the whole reservoir basin seepage prevention must be adopted for the reservoir of the pumped storage power station, the dam seepage prevention form and the reservoir basin seepage prevention form should be considered as a whole, so as to avoid or reduce the joint treatment between different seepage prevention structures as much as possible and improve the reliability. The whole reservoir basin with high backfill shall be used for seepage prevention at the bottom of the reservoir. The seepage prevention structure at the bottom of the reservoir shall be suitable for large deformation or uneven deformation caused by high backfill.
The water head of the pumped storage power station is high, and the pressure borne by the water channel structure is large. According to the water head, the geological conditions of surrounding rock, the size of bifurcated pipe, etc., steel lining, reinforced concrete lining and other methods can be adopted.
In addition, in order to ensure the flood control safety of the power station, the pumped storage power station also needs to arrange flood discharge structures, etc., which will not be detailed here.
3. Construction organization design
The main tasks of the construction organization design of the pumped storage power station include: study the project construction conditions, construction diversion, material source planning, main project construction, construction transportation, construction plant facilities, general construction layout, general construction schedule (construction period), etc.
In the design work, we should make full use of the topographic and geological conditions of the station site, combine the construction conditions and the engineering design plan, and in the principle of intensive and economical land use, initially draw up the engineering construction plan, earthwork balance and general construction layout plan, so as to minimize the occupation of arable land and reduce the project cost.
As a major construction country, China’s construction management and construction level are world-famous. In recent years, China’s pumped storage has made many beneficial explorations in green construction, R&D and application of key equipment, and intelligent construction. Some construction technologies have reached or advanced the international level. It is mainly reflected in the increasingly mature dam construction technology, the new progress of high-pressure bifurcated pipe construction technology, the large number of successful practices of underground powerhouse cavern group excavation and support technology under complex geological conditions, the continuous innovation of inclined shaft construction technology and equipment, the remarkable achievements of mechanized and intelligent construction, and the breakthrough of TBM in tunnel construction.
4. Electromechanical and metal structure
Vertical shaft single-stage mixed-flow reversible storage units are generally used in pumped storage power stations. In terms of hydraulic development of pump-turbines, China has the design and manufacturing capacity of pump-turbines with 700m head section and 400000 kilowatts per unit capacity, as well as the design, manufacturing, installation, commissioning and production of many storage units with 100-700m head section and 400000 kilowatts or less per unit capacity. In terms of water head of the power station, the rated water heads of Jilin Dunhua, Guangdong Yangjiang and Zhejiang Changlongshan pumped storage power stations under construction are all more than 650m, which are in the forefront of the world; The approved rated head of Zhejiang Tiantai Pumped Storage Power Station is 724m, which is the highest rated head of pumped storage power station in the world. The overall design and manufacturing difficulty of the unit is at the world’s leading level. In the development of generator motors, the large generator motors of pumped storage power stations built and under construction in China are vertical shaft, three-phase, fully air-cooled, reversible synchronous motors. There are two units of Zhejiang Changlongshan Pumped Storage Power Station with rated speed of 600r/min and rated capacity of 350000 kW. Some units of Guangdong Yangjiang Pumped Storage Power Station have been put into operation with rated speed of 500r/min and rated capacity of 400000 kW. The overall manufacturing capacity of generator motors has reached the world’s advanced level. In addition, electromechanical and metal structures also include hydraulic machinery, electrical engineering, control and protection, metal structures and other aspects, which will not be repeated here.
The equipment manufacturing of pumped storage power stations in China is developing rapidly in the direction of high water head, large capacity, high reliability, wide range, variable speed, and localization.
5、 Economic indicators
The construction conditions and external impact of a pumped storage project, after determining the project design scheme, will ultimately be mainly reflected in an indicator, namely the static investment per kilowatt of the project. The lower the static investment per kilowatt, the better the project economy.
The individual differences in the construction conditions of pumped storage power stations are obvious. The static investment per kilowatt is closely related to the construction conditions and installed capacity of the project. In 2021, China approved 11 pumped storage power stations, with an average static investment of 5367 yuan per kilowatt; 14 projects have completed the pre-feasibility study, and the average static investment per kilowatt is 5425 yuan/kilowatt.
According to the preliminary statistics, the static investment per kilowatt of large pumped storage projects that are under preliminary work in 2022 is generally between 5000 and 7000 yuan/kilowatt. Due to different regional geological conditions, the average level of static investment per kilowatt of pumped storage energy in different regions varies greatly. Generally speaking, the construction conditions of power stations in the south, east and central China are relatively good, and the static investment per kilowatt is relatively low. Due to poor engineering geological conditions and poor water source conditions, the unit cost level in the northwest region is relatively high compared with other regions in China.
For investment decisions, we need to focus on the static investment per kilowatt of the project, but we can’t just talk about the hero of the static investment per kilowatt, otherwise it may lead to the impulse of enterprises to blindly expand the scale. Mainly reflected in the following aspects:
First, increase the installed capacity initially proposed at the planning stage. We should take a dialectical view of this situation. Take a project with a planned installed capacity of 1.2 million kilowatts at the beginning of the planning stage as an example, and its unit composition is four 300000 kilowatts units. If the range of water head is appropriate, and with the progress of technology, the conditions for selecting 350000kW of single machine are available, then after comprehensive technical and economic comparison, 1.4 million kW can be recommended as the representative scheme in the pre-feasibility stage. However, if the original planned 4 units of 300000 KW are now considered to increase 2 units to 6 units of 300000 KW, that is, the installed capacity of the power station is increased from 1.2 million KW to 1.8 million KW, then it is generally believed that this change has changed the functional orientation of the project, and it needs to further consider the planning compliance, power system needs, project construction conditions and other factors comprehensively. In general, the increase in the number of units should fall within the scope of planning adjustment.
The second is to reduce the full utilization hours. If pumped-storage energy is compared to a charging bank. Then the installed capacity can be used as the output power, and the full utilization hours are how long the power bank can be used. For pumped-storage power stations, when the stored energy is the same, the full utilization hours and installed capacity can be comprehensively compared. At present, according to the needs of the power system, the daily regulated pumped storage full utilization hours are considered as 6h. If the construction conditions of the power station are good, it is appropriate to appropriately increase the full utilization hours of the unit at a low cost. With the same static investment per kilowatt, the power station with higher full utilization hours can play a greater role in the system. However, there has been the idea that the installed capacity will be significantly increased (1.2 million kW → 1.8 million kW) and the utilization hours of full capacity will be reduced (6h → 4h). In this way, although the static investment per kilowatt can be greatly reduced, for the system, the short utilization time cannot meet the system demand, and its role in the power grid will also be greatly reduced.
Post time: Mar-08-2023
