According to the forecast from the Nanjing Purple Mountain Observatory of the Chinese Academy of Sciences, 2020, on June 21 this year, there will be an "circular solar eclipse" passing through the territory of our country, and astronomy in Tibet, Sichuan, Guizhou, Hunan, Jiangxi, Fujian, Taiwan and other places Enthusiasts have the opportunity to see the wonder of the annular solar eclipse, and partial solar eclipses can also be seen in other parts of our country.
The entire solar eclipse process is about 2 and a half hours in China, starting from the partial eclipse at 14:43 Beijing time, the ring eclipse at 16:10, the ring eclipse at 16:11, and the partial eclipse at 17:24.
For ordinary people, an annular solar eclipse may be just a rare spectacle, but for photovoltaic power plants that rely on solar energy, it is a natural disaster. The reduction of solar radiation caused by the solar eclipse will directly affect the power generation of photovoltaic power generation systems and test the stability of our country's power system.
The impact of solar eclipses on photovoltaic power generation in recent years:
On March 20, 2015, Germany ushered in a total solar eclipse. As the largest photovoltaic power generation country in Europe, Germany's photovoltaic power generation can account for more than half of its maximum electricity consumption. According to reports, after the solar eclipse began, the power of photovoltaic power generation in Germany was instantly reduced by 12 million kilowatts, affecting the equivalent of 10 nuclear power plants being out of operation at the same time. When the sun drilled out from behind the moon, under the sudden sunlight, 19 million kilowatts of photovoltaic power generation entered the grid in a short time, which is equivalent to 20 nuclear power plants suddenly connected to the grid. One retreat and one advance occur instantaneously, causing serious impact on the power grid. This is the rare event in German history and the world where celestial phenomena pose a threat to power grid security.
On August 21, 2017, the solar eclipse hindered the normal operation of solar power plants and solar cells in many parts of the United States. The solar eclipse has an impact on photovoltaic power generation systems in many states in the United States. California, with the largest installed solar capacity in the United States, has 60%-80% of sunlight blocked, and in North Carolina, over 90% of the sunlight is blocked. According to statistics, 21.75 million kilowatts of photovoltaic power plants were affected, and solar power generation was reduced by 250 megawatts (enough to use about 7 million households).
On July 2, 2019, a solar eclipse appeared over the South Pacific and South America. In recent years, the power generation of unconventional renewable energy in Chile has been increasing. Currently, the proportion of photovoltaic power generation in Chile's total power generation has reached 9.4%. When the total solar eclipse occurred, Chile's photovoltaic output power fell from the highest of the day of 1.45 million kilowatts to less than 200,000 kilowatts.
my country opened a new era of photovoltaic power generation in 2013, and it has developed rapidly at a compound annual growth rate of more than 70%. As of the end of 2019, the country’s cumulative installed photovoltaic power generation capacity exceeded 204 million kW, firmly occupying the top spot in the global photovoltaic power generation capacity. Photovoltaic accounts for about 9% of the country's total installed capacity and 2.5% of the country's total power generation. Such a large proportion of installed photovoltaic power generation capacity and power generation capacity will usher in the test of the "circular eclipse" for the first time on June 21 this year.
Will the solar eclipse " eat " China's power grid?
Experts said that the normal operation of the grid needs to maintain a real-time balance between power generation and electricity consumption. From the perspective of facilitating grid control and regulation, the output of the power supply should be relatively stable. However, the characteristics of photovoltaic power generation determine its instability. During a solar eclipse, the light first drops sharply in a short period of time, and then suddenly rises. This is a very big challenge to the rapid adjustment ability of the power system. .
Just imagine, if on a sunny day, the photovoltaic output will reach a very high value, a total solar eclipse suddenly occurs, and the photovoltaic output will drop to zero within a few minutes. Due to the dimming of the light, many users will turn on the lighting, and the electricity load will continue to increase. After the total solar eclipse, photovoltaic output will continue to rise from zero in just a few minutes.
Thus, means must Yajian appropriate scale power generation load balancing to maintain real-time power system, which is a very difficult problem to face grid dispatching department, the equivalent of a large nuclear power plant within a short time of tripping and reclosing, if not Forming correct regulation can completely collapse the entire power grid.
In response to the solar eclipse, my country's power grid has the following three measures:
(1) Photovoltaic power prediction will predict the photovoltaic power curve after the solar eclipse will be affected in advance based on the scope and time of the solar eclipse, and the power supply network will make adequate plans.
Photovoltaic power forecasting manufacturers, such as Xiangxinli Technology , began to pay attention to the impact of solar eclipse on photovoltaic power generation three months ago. With reference to foreign solutions to the prediction of solar eclipse impact on photovoltaic power generation, considering multiple weather scenarios on the day of the eclipse, the total horizontal radiation on the day of the total solar eclipse was predicted several months in advance. Furthermore, during the week of the solar eclipse, according to the rolling update weather forecast information, the solar eclipse solar power forecast will be revised daily to improve the forecast accuracy, provide accurate power forecast services for the photovoltaic power plant, and the power supply network will make adequate plans to provide data support.
(2) Prepare sufficient spare capacity. Before the solar eclipse, China's power grid will prepare sufficient reserve capacity in advance to provide safety guarantees against photovoltaic fluctuations.
(3) Give full play to the regulation role of controllable power generation methods such as coal-fired and hydropower, and effectively balance the fluctuation of photovoltaic power generation. From the perspective of my country's power generation structure, thermal power generation currently accounts for about 73% of the country's total power generation, occupying an absolute dominant position, with hydropower accounting for 18%. Thermal and hydropower have the advantages of stability and controllability and will play an important role in responding to the impact of the solar eclipse on photovoltaic power generation.
Will the solar eclipse "eat" China's power grid?
The answer is: no!