白鶴灘水電站：在金沙江上鑄就“國家名片”

文：《科技日報》 付麗麗

白鶴灘水電站 Baihetan Hydropower Station

白鶴灘水電站投入使用后，每年平均發(fā)電量約為624.43 億千瓦時，一天的發(fā)電量可滿足50 萬人一年的生活用電。每年可節(jié)約標準煤約2500 萬噸，減排約6500 萬噸二氧化碳、60 萬噸二氧化硫，相當于少建近6 座年產(chǎn)400萬噸的大型煤礦。

截至2 月17 日，白鶴灘水電站累計安全生產(chǎn)綠色電能200 億千瓦時，相當于減少標準煤消耗624 萬噸，減少二氧化碳排放1602 萬噸。前不久，白鶴灘水電站交出亮麗的成績單。

國產(chǎn)機組單機容量100 萬千瓦，世界第一；總裝機容量1600 萬千瓦，僅次于三峽水電站，位居世界第二。2021 年6 月28 日，白鶴灘水電站首批機組正式投產(chǎn)發(fā)電。

在川滇兩省交界的金沙江上，白鶴灘與其上游的烏東德，下游的溪洛渡、向家壩、三峽、葛洲壩水電站共同構(gòu)成一條世界上最大的清潔能源走廊。

世界首臺最大的百萬千瓦水輪機組、世界最大的地下廠房、世界“最聰明”的智能大壩……大國重器白鶴灘水電站實現(xiàn)了多個世界之最。這背后，是中國幾代水電人幾十年如一日的不懈探索，他們一步一個腳印，用行動書寫出中國水電裝備由并跑向領(lǐng)跑沖刺的神話。

特種水泥解決“無壩不裂”難題

壩高289 米，相當于100 層樓高，整體澆筑低熱混凝土803 萬立方米，體積超過3 個胡夫金字塔——從外形看，白鶴灘水電站絕對是個大塊頭。

2021 年5 月29 日，白鶴灘水電站大壩最后一倉溢流面混凝土澆筑完成，這標志著大壩表孔已具備過流條件。

白鶴灘水電站處于V 型河谷，兩岸懸崖峭壁，復(fù)雜的地質(zhì)條件決定其只能采用混凝土雙曲拱壩，以使受力更科學(xué)，同時節(jié)省壩體材料，提高安全性。

在業(yè)界，“無壩不裂”是橫亙在水電站建設(shè)過程中的世界級難題。白鶴灘水電站尤其如此。規(guī)模巨大，壩體結(jié)構(gòu)不對稱，加上持續(xù)的干熱、大風(fēng)天氣，導(dǎo)致溫控難度極大。

為此，科研人員研制出特種水泥——低熱硅酸鹽水泥，也叫低熱水泥。它具有水化熱低、放熱速率慢、堿含量低、后期強度增進率高等優(yōu)良性能，為解決大體積混凝土開裂問題提供了更好的技術(shù)途徑。同時，在每一處澆筑的混凝土中，都埋設(shè)有數(shù)支溫度傳感器和循環(huán)冷卻水管，可以實時監(jiān)測混凝土內(nèi)部的溫升，并進行有針對性的降溫。

自開澆以來，白鶴灘水電站大壩沒有出現(xiàn)一條溫度裂縫。2019 年，在鉆孔取芯質(zhì)量檢查過程中，技術(shù)人員從大壩取出25.7 米混凝土長芯，混凝土芯樣光滑密實、骨料分布均勻、氣泡少。這樣一份高質(zhì)量混凝土澆筑施工成績單的背后，是建設(shè)者對大國重器質(zhì)量細節(jié)的精準把控。

鳥瞰白鶴灘水電站Aerial view of Baihetan Hydropower Station

“最強大腦”提升工程效率

從長江到金沙江，三峽集團組織創(chuàng)新“300 米級溪洛渡拱壩智能化建設(shè)關(guān)鍵技術(shù)”，開創(chuàng)了中國智能高拱壩建設(shè)的先河。

白鶴灘水電站進一步借助物聯(lián)網(wǎng)、云計算以及大數(shù)據(jù)等技術(shù)，向建設(shè)管理智能化又邁出了一大步。

在白鶴灘工程建設(shè)部技術(shù)管理部副主任周孟夏看來，手機中安裝的智能通水系統(tǒng)和施工過程智能監(jiān)控系統(tǒng)，是他最親密的“工作伙伴”。

“大壩施工中，混凝土溫度控制的主要手段是冷卻通水。按照規(guī)范，至少每4 個小時就要對所有倉號進行一次測溫，需要投入大量的人員手工操作，對大壩溫度情況掌握也比較滯后。”

如今，智能通水系統(tǒng)不僅能實時感知溫度，還可以自主分析溫度變化趨勢，按照預(yù)設(shè)的控制算法進行自動調(diào)控。在降低人工作業(yè)強度的同時，極大提升了工程效率與溫控精度。

“這個‘最強大腦’還可以積累工程實踐數(shù)據(jù)，通過大數(shù)據(jù)分析完善預(yù)設(shè)的經(jīng)驗算法，進行部分自主決策，進而實現(xiàn)現(xiàn)場快速響應(yīng)。如此一來，工程師便能從大量日常管理工作中解放出來，僅在數(shù)據(jù)異常時糾編處理即可，管理效率隨之提高。”周孟夏介紹。

“最強大腦”高效整合物質(zhì)流與數(shù)據(jù)流，為精細化施工創(chuàng)造了更大的空間。

“以混凝土振搗為例，振搗幾遍，振搗棒型號如何選擇，初振多久，復(fù)振多久，這些專業(yè)試驗的參數(shù)，都會印成標準化工藝手冊，用以培訓(xùn)員工。”白鶴灘工程建設(shè)部大壩項目部工程師劉春風(fēng)介紹。

如今，這些標準被“翻譯”成代碼進入智能系統(tǒng)，智能系統(tǒng)實時分析振搗棒的覆蓋范圍、插入深度、振搗時長等數(shù)據(jù)是否“合格”，讓施工質(zhì)量不再僅靠人工肉眼觀察和經(jīng)驗判斷，而是“數(shù)”說了算。

工人在焊接施工A worker is carrying out welding

勇登水電行業(yè)“珠穆朗瑪峰”

100 萬千瓦巨型水輪發(fā)電機組，是世界水電行業(yè)的“珠穆朗瑪峰”。白鶴灘水電站機組是全球單機容量最大的水電機組，也是中國自主設(shè)計制造的完全國產(chǎn)化百萬千瓦機組，研制與安裝難度遠大于世界在建和已投運的任何機組。

在白鶴灘建水電站的設(shè)想始于20 世紀五十年代。當時，在研討白鶴灘水電站機組單機容量的時候，為穩(wěn)妥起見，有專家提出采用兩臺100 萬千瓦機組，其余機組采用80 萬千瓦的方案。最終決定16 臺機組全部用國產(chǎn)百萬千瓦水輪發(fā)電機組，是在2006 年。

對于選擇100 萬千瓦機組，白鶴灘工程建設(shè)部主任汪志林是這樣解釋的，其一是具備建設(shè)能力，其二是客觀要求。白鶴灘兩岸均為雄厚山體，復(fù)雜地質(zhì)條件已帶來一系列世界級難題。在樞紐建筑工程布置上，單機容量越大，機組臺數(shù)就越少，地下洞室群、地下廠房的規(guī)模將更趨合理，穩(wěn)定性安全性也會更好。其三是資源稟賦，金沙江干流落差大，水流湍急，白鶴灘水電站是高壩大庫，水頭高達200 多米，從水能利用率來看，可以滿足1600 萬千瓦的總裝機容量。而最重要的一條是，中國現(xiàn)代化經(jīng)濟社會發(fā)展需要與之相適應(yīng)的大規(guī)模清潔電能的支撐，白鶴灘水電站是國家重大工程，是西電東送骨干電源點，遠景發(fā)展電力的需要為其提出更高要求。

“水電是清潔能源的主力軍。而白鶴灘水電站即將加入中國清潔能源的主力陣容，備受關(guān)注。”中國科學(xué)院院士錢七虎說，電站建設(shè)本身亦是對藍天的守護，對人類可持續(xù)發(fā)展有重要意義。

在保護中發(fā)展、在發(fā)展中保護。助力實現(xiàn)“碳達峰、碳中和”目標，中國水電人正在持續(xù)書寫生態(tài)文明的新時代答卷。

After being put into operation, the Baihetan Hydropower Station will generate an average of 62.443 billion kWh of electricity per year, and the electricity it generates per day can meet the annual consumption demands of 500,000 people. It can save about 25 million tons of standard coal, reduce carbon dioxide emissions by about 65 million tons and sulfur dioxide emissions by 600,000 tons every year, which is equivalent to reducing nearly six large coal mines with an annual output of 4 million tons.

A total of 20 billion kWh of green electricity has been safely produced till Feb.17 by Baihetan Hydropower Station, equivalent to reducing standard coal consumption by 6.24 million tons and carbon dioxide emissions by 16.02 million tons. Not long ago, the Baihetan Hydropower Station set multiple world records.

Using domestically produced generating units with a unit capacity of 1 million kW, it ranks first in the world.With a total installed capacity of 16 million kW, it ranks second only to the Three Gorges Hydropower Station in the world. On June 28, 2021, the first units of Baihetan Hydropower Station were put into operation.

On the Jinsha River at the junction of Sichuan and Yunnan provinces, Baihetan has established the world’s largest clean energy corridor, together with upstream Wudongde and downstream Xiluodu,Xiangjiaba, Three Gorges and Gezhouba hydropower stations.

As a pillar of a great nation, the Baihetan Hydropower Station has set multiple world records, including the world’s first and largest million-kWclass hydro-generator unit, the world’s largest underground plant, and the world’s “smartest” intelligent dam.These outcomes should be credited to the decades of unremitting exploration of Chinese builders. Step by step, they have developed cutting-edge hydropower equipment, propelling China into a leading position.

白鶴灘水電站單機容量位居世界第一The Baihetan Hydropower Station has the world’s largest unit capacity

Special cement solves the problem of “no dam without cracks”

The dam is 289 meters high,equivalent to a 100-story building.With a total volume of 8.03 million cubic meters of low-heat concrete, the Baihetan Hydropower Station is more than three times the size of the Great Pyramid of Khufu.

On May 29, 2021, concreting of the overflow surface was completed, which indicated that the surface outlets of the dam were ready for flood discharge.

The Baihetan Hydropower Station is located in a V-shaped river valley with cliffs on both sides. Due to the complex geological conditions, it can only use a double-curvature arch dam made of concrete to scientifically disperse the stress, save building materials and improve safety.

As the saying goes, “there is no dam without cracks.” Dam cracking is a universal problem in the construction of hydropower stations. This is especially true of the Baihetan Hydropower Station. The large scale and asymmetric structure of the dam, coupled with the continuous dry heat and strong winds,made temperature control extremely difficult.

To address this problem, researchers developed a special cement — low-heat Portland cement, also known as lowheat cement. It has the advantages of low hydration heat, low heat release rate, low alkali content and high growth rate of later strength, which provides a better technical approach to solving the cracking problem of mass concrete. Moreover, in the concrete poured in each place,several temperature sensors and circulating cooling water pipes are embedded to monitor the temperature rise inside the concrete in real time and conduct targeted cooling.

Not a single temperature crack has appeared in the dam since concreting. In 2019, a 25.7-meter-long concrete core sample was taken out of the dam during the quality inspection of core drilling. The core sample was smooth and dense,with uniform aggregate distribution and few air bubbles.Such a high-quality concreting construction is a result of the builders’ solid efforts in quality control.

“Superbrain” improves project efficiency

From the Yangtze River to the Jinsha River, the China Three Gorges Corporation has made innovations in “key technologies for the intelligent construction of the 300-meterhigh Xiluodu arch dam” to build the first intelligent high arch dam in China.

The Baihetan Hydropower Station has further taken a big step towards intelligent construction management with the help of such technologies as the Internet of Things, cloud computing and big data.

According to Zhou Mengxia, Deputy Director of the Technical Management Office of Baihetan Project Construction Department, the intelligent water supply system and the intelligent monitoring system for the construction process installed in his phone are his best “working partners”.

“During the construction of the dam, cooling water is the main approach to controlling the concrete temperature.According to the regulations, temperature measurements should be carried out at least every four hours at all warehouses,which requires a large number of manual operations and has the problem of slow information transfer of dam temperatures.”

Nowadays, the intelligent water supply system can not only sense the temperature in real time, but also analyze the temperature change trend and adjust the temperature automatically according to the preset control algorithm. In addition to reducing manual operations, the project efficiency and temperature control accuracy are greatly improved.

“This ‘Superbrain’ can also accumulate project practice data,improve preset empirical algorithms through big data analysis,conduct autonomous decision-making to some extent, and achieve rapid on-site response. This frees engineers from a load of daily management work. They only need to make corrections when there is a data anomaly. In this way, the management efficiency is improved.” Zhou Mengxia introduced.

This “Superbrain” efficiently integrates material flow and data flow, creating more space for lean construction.

“Taking concrete vibrating as an example, the parameters about how many times to vibrate, how to choose the type of vibrating rod, how long it takes for initial vibration, and how long for re-vibration will be included in a standardized process manual used for training employees.” Liu Chunfeng, Engineer of the Dam Project Office of the Baihetan Project Construction Department, introduced.

Now, these standards are “translated” into codes and entered into the intelligent system. The intelligent system can analyze in real time whether the coverage of the vibrator, the insertion depth,vibrating duration and other data “meet the standards”, so that the construction quality is no longer judged by manual observation and experience, but the real data.

Conquering the “Mount Everest” in the hydropower industry

The 1-million-kW capacity hydro-generator unit is dubbed as the “Mount Everest” in the hydropower industry. The Baihetan Hydropower Station has the world’s first and largest million-kW-class hydro-generator unit, which is designed and manufactured by China. The development and installation of such a generator unit is much more difficult than any other generator units under construction or in operation in the world.

The idea of building a hydropower station in Baihetan was put forward in the 1950s. When discussing the unit capacity of Baihetan Hydropower Station, for the sake of safety, some experts proposed to use two 1 million-kW generator units and some 800,000-kW generator units. The final decision was made in 2006 to use 16 homemade million-kW-class hydro-generator units.

Wang Zhilin, Director of the Baihetan Project Construction Department, explained that the decision on the 1 million-kW hydro-generator unit is based on the construction ability and objective demands. The complex and mountainous geological conditions on both riversides of Baihetan have brought a series of bugbears to the project. In the layout of major buildings, the large unit capacity will contribute to a smaller number of units, a more appropriate size of underground caverns and plants,and stronger stability and safety. In terms of resource endowment, the main stream of the Jinsha River has a large drop and rapid water flow. The Baihetan Hydropower Station has a high dam and a huge reservoir, with a water head of more than 200 meters. From the perspective of hydro-energy utilization efficiency, it has a total installed capacity of 16 million kW.

Most importantly, China’s modern economic and social development requires the support of large-scale clean electricity generation projects that are compatible with it. The nationalclass project of Baihetan Hydropower Station serves as a key power source of the West-to-East Power Transmission Project, and meets the high demands of long-term electricity development.

“Hydropower is an integral part of clean energy. The Baihetan Hydropower Station will soon join the main force of developing clean energy in China, and it has garnered much attention.” Qian Qihu,an academician of the Chinese Academy of Sciences, said that the construction of the power station represents an effort to protect our environment and to realize the sustainable development.