A full view of the upper and lower reservoirs of the Changlongshan Pumped Storage Power Station
A pumped storage power station was built in Changlongshan, Zhejiang. Many people don’t understand what is going on. In fact, the principle is very simple. That is, first build two reservoirs, the upper and the lower, to use electricity. Pump water from the lower reservoir to the upper reservoir, and then release water from the upper reservoir to the lower reservoir to generate hydropower.
Is there such a "sexy operation"? Electricity pumps water and then generates electricity. What is this for? Too busy to do anything? In fact, there are quite a few netizens who have this idea. They are mainly divided into two categories. One category is those who don’t understand anything at all and think it is unnecessary to take off their pants and fart. The other category is those who have a little knowledge base and want to ask about the process. Loss and energy conservation issues with . We have excerpted a part for your reference.
These two types of netizens have one thing in common - and they oppose pumped storage power stations . Is it true that netizens like these are either making fun of or making useless excuses for professionals?
We have not built enough pumped storage power stations.
This technology and project of pumped storage power stations is not the first of its kind. As early as 1882, more than 100 years ago, Switzerland built the Netra pumped storage power station, which was the world's first pumped storage power station. In the 1950s and 1960s, developed countries entered the peak period of pumped storage power station construction. So far, the installed capacity of pumped storage power stations in developed countries in the world generally accounts for 3% to 5% of the total installed capacity of their power grids. In comparison, the proportion of installed capacity of pumped storage power stations in my country is still at a medium to low level. You see, it’s not that we have nothing to do, but that we didn’t have that much money for construction before, so we didn’t build enough.
Four kilowatt-hours of electricity are exchanged for three kilowatt-hours of electricity
The reason why some netizens criticize pumped storage power stations is that they use static thinking to look at problems. They ignore or confuse two issues: First, the electricity consumed by pumping water and the electricity generated by releasing water. It is the same? Second, are pumping and releasing water at the same time?
Pumped storage power station is mainly composed of an upper reservoir, a lower reservoir, and a reversible water pump turbine. The working process of the power station seems to be the energy cycle of "grid electric energy → unit mechanical energy → water body potential energy → unit mechanical energy → grid electric energy". Following this line of thinking, opponents believe that the electricity from the grid circulates through pumped storage power stations, and nothing seems to be gained except losses.
Looking at the pumped storage power station statically, part of the electric energy will be lost during the entire energy conversion process. Even the current large-scale pumped storage power station has a comprehensive efficiency of more than 75%, and the highest is only 80.6%. This is some People say " four kilowatt-hours of electricity for three kilowatt-hours of electricity ", which does not make sense when calculated, but are pumped storage power stations really so meaningless? What's the problem?
The principle of pumped hydropower generation
First we look at when water is pumped. During the low load period of the entire power system (often at night), the grid consumes less electricity, and the power plant generates the same amount of electricity as during the day. However, there is an important common sense - electricity cannot be stored in the grid, so what should we do?
has two solutions: one is to generate less electricity, and the other is to consume unused electricity. Why is it not possible to generate less electricity? We will explain in detail in a moment. Let’s talk about the second option first, how to consume the excess electricity. This is where pumped storage power stations come in handy.
The main workshop of the reversible water pump turbine
uses the surplus electric energy of the power grid to adjust the reversible water pump turbine to the water pump working mode, pumping the water from the lower reservoir to the upper reservoir. At this time, the electric energy is consumed and converted into the water in the upper reservoir. Gravity potential energy, pumped storage power station is a user in the power grid, thus "temporarily storing" excess electricity. During the day, the power consumption of the power grid increases. At this time, the power generation of the power plant alone is not enough. At this time, the reversible water pump turbine is adjusted to the power generation mode, and the pre-stored water in the upper reservoir is put down and flows to the lower reservoir, while promoting The hydraulic turbine generates electricity and sends it to the power grid for use. At this time, the pumped storage power station becomes a power source in the power grid.
Water supply water tower
This is similar to the water tower in cities and towns. When there is little water in the pipe network, the water is stored in the water tower first, and then released when the water demand is at peak, it becomes a water source. Look at it this way, the pumped storage power station itself not only generates electricity, but also has the function of energy storage, so some places call it a "power bank" in the power grid.
Why can’t we generate less electricity when we use less electricity?
Many netizens have this question. They think that "it's just a matter of shutting down a few units". In this way, if it is used less, it will be sent less, and if it is used more, it will be sent more. It will be good to balance supply and demand. In this way, it can save money for construction and pumping. Funds for energy storage power stations come. This can only be described as layman’s thinking.
Let’s first look at the situation in developed countries. The scale of pumped storage power station construction in developed countries mainly depends on the country's power energy structure. If the proportion of nuclear power and coal power is high, then the proportion of pumped storage power station construction will be high. Why is this?
Full view of the upper and lower reservoirs of Changlongshan Pumped Storage Power Station
To give a simple example, nuclear power is suitable for long-term stable operation with base load. In layman's terms, it means don't stop when you start driving. The larger the scale, the more conducive to emission reduction, but it will Peak shaving has brought great pressure to the power system dominated by coal power. Because nuclear power must have a stable and balanced output, and the single-machine capacity of nuclear power units is very large, once it is shut down at will, it will have a great impact on the power grid, and may even cause the power grid to collapse.
There are also new energy power generation such as wind power, geothermal, tidal, and solar energy. are also useful supplements to my country's power grid structure. However, these electricity are sometimes called "garbage power", especially wind power, which is random and intermittent. The stability and continuity of power generation are poor. After the power is connected to the grid, it poses a huge challenge to the real-time balance of the power system and the safe and stable operation of the power grid. It would be a pity to throw away these "fragmented power".
So we took advantage of the flexible start-up characteristics of pumped storage power stations to temporarily transfer this surplus electricity, fragmented electricity, and garbage electricity into the potential energy of water. When the demand for electricity increases, it can be released to generate electricity.
Functions of pumped storage power stations
Valley storage and peak replenishment
Through the above introduction, we finally know the key role of pumped storage power stations, which is "valley storage and peak replenishment". When the electricity load is low, the surplus electricity from other power sources in the power grid (thermal power, nuclear power, hydropower, wind power, solar power, etc.) is absorbed and "disguised" as water in the reservoir; when electricity consumption peaks, Turn water into electricity to supplement grid needs. In this way, thermal power and nuclear power, which need stable and balanced output to improve efficiency, can work with peace of mind, and no longer have to worry about the problem of generating more power and less power; at the same time, the waste water of run-of-river hydropower stations, wind power, solar power and other power generation will be reduced. , abandoned wind, and abandoned electricity are collected in disguised form to make these fragmentary electricity valuable.
Accident backup
Pumped storage power station also has some other non-main functions, but it is also very useful, that is, accident conditions. For example, if some of the main power sources in the power grid suddenly stop supplying power, or the load on the power grid suddenly increases or decreases, then pumped storage power stations come in handy. When it is needed to generate electricity, it can immediately switch from water pumping mode to power generation mode to make up for the power gap caused by main power supply accidents or sudden load increases. If the load of the power system suddenly decreases, the pumped storage power station can immediately switch to pumping mode and store the excess electricity in the reservoir. This two-way function can be said to be one of the best configurations for power system emergency backup.
black start
If the power grid encounters a major collapse and there is no external power supply support, the pumped storage power station will play the role of a "power bank". It can quickly start generating power in a short period of time, allowing the power system to quickly recover. Without such black start measures, the power outage time of the power grid will be extended and the losses will be huge.
History of pumped storage power station construction in my country
In mainland my country, the construction of pumped storage power stations has mainly gone through three stages. The first stage of
(1968~1991) is the hybrid pumped storage power station stage.my country's first pumped storage power station was the Hebei Gangnan Power Station built in 1968, with an installed capacity of 11MW. The construction of the Yamzhuo Yonghu Power Station began in 1989, during which time Miyun, , Panjiakou, and other power stations were successively built.
The second stage (1992~2002) is the initial stage of the development of large-scale pumped storage power stations. Construction of Mingling, Guangshu, Tianhuangping and other power stations began.
The third phase (2003 to present) is a period of vigorous construction of large-scale pumped storage power stations. During this period, a number of large-scale projects were built, including Baoquan, Xilongchi, Tongbai, Huizhu, Zhanghewan, Yixing, Bailianhe, Liyang, Hongping, Xianju, Fengning, and Changlong Mountain. power station.
According to statistics, by the end of 2017, the installed capacity of pumped storage power stations in mainland my country has ranked first in the world. However, compared with developed countries, our construction ratio is far from enough.
Changlongshan Pumped Storage Power Station
Zhejiang Changlongshan Pumped Storage Power Station is located in Tianhuangping Town, Anji County, Zhejiang Province. It is the second pumped storage power station invested and developed by Three Gorges Corporation after the Hustorage Power Station. This power station is a daily regulated pure pumped storage power station, equipped with 6 single-stage single-speed vertical shaft mixed-flow reversible pumped storage units with a single unit capacity of 350,000 kilowatts, with a total installed capacity of 2.1 million kilowatts.
The rated water head between the upper and lower reservoirs is as high as 710 meters. This is the pumped storage power station with the highest rated water head in my country. The construction of this power station marks that my country has reached a new level in the fields of pumped storage power station design, construction, and equipment manufacturing. On November 27, 2016, China Three Gorges Corporation, East China Survey and Design Institute, China Gezhouba Group and other units officially announced the construction of the Changlongshan Pumped Storage Power Station. The power station mainly consists of an upper reservoir, a lower reservoir, a water transmission system, an underground factory building and a ground switching station. It undertakes tasks such as peak shaving and valley filling of the East China Power Grid. It adjusts the power supply structure in East China, improves power grid operating conditions, promotes energy development and provides services. The national energy structure adjustment strategy is of great significance. The investment in this project is 48.6 billion yuan, with a total investment of 10.6 billion yuan.
This article provides some simple science popularization to some non-professional netizens who are concerned about the development of the country. The purpose is to tell them that professional things are done by professionals. If you don’t understand, you can ask for advice humbly. If you have questions, you can ask, but don’t criticize casually. After all, professionals know better than trolls. I believe that the country’s major strategic decisions are made through scientific decision-making by professional think tanks, rather than being slapped on the head casually.
Reference materials:
1, "Key Technologies for the Construction of Large Pumped Storage Power Stations", Zhang Lirong
2, "Five Years of Hard Work", China Three Gorges Corporation
would like to express my gratitude!
