Gorges Power Research Articles

Simulation of Water Level and Flow of Catastrophic Flood Based on the CNN-LSTM Coupling Network

The occurrence of catastrophic floods will increase the uncertainty of hydrological forecasting at downstream hydrological stations. In order to solve the problems of the unclear propagation law of catastrophic floods in the middle and lower reaches of the Yangtze River and the inadaptability of traditional forecasting methods, this paper uses the M-K trend test method to analyze the annual average flow and annual average water level of the Yichang and Hankou stations. For conventional floods and catastrophic floods, Random Forest (RF), Convolutional Neural Network (CNN), Long Short-Term Memory Network (LSTM), and CNN-LSTM neural networks are used to simulate the water level/flow of Hankou station. The simulation results are analyzed by Nash–Sutcliffe Efficiency Coefficient (NSE), Kling–Gupta efficiency coefficient (KGE), Root Mean Square Error (RMSE), and Symmetric Mean Absolute Percentage Error (SMAPE). The results show that the annual average flow and annual average water level of Yichang station show a downward trend and the annual average water level of Hankou station shows an upward trend. By comparing the four indicators of NSE, KGE, RMSE, and SMAPE, the CNN-LSTM coupling model was determined to be the best fitting model, with NSE and KGE greater than 0.995 and RMSE and SMAPE less than 0.200. The proposed coupling model can provide technical support for flood control optimization, scheduling, emergency rescue, and scheduling impact analysis of the Three Gorges Power Station.

Analysis on Energy Saving of Large Scale Public Building Economy Taking Kaifeng City as an Example

Today, in Chinese existing large public building energy conservation is facing severe challenges, but also has great potential. In this paper, taking Kaifeng city as an example to survey and analysis on energy consumption of large public buildings in China, and the proposed modification proposal for reference. According to the current trends, by 2020 China's annual energy consumption will reach 10.9 tons of standard coal, equivalent to about 29 430 billion kwh of electricity, it is more than 34 times the total annual power generation of Three Gorges power station. Among them, the existing large-scale public buildings consume 22% of the total energy consumption, has become the black hole and giant, although their construction area of less than 4% of total urban construction. According to statistics, the total construction area of large public buildings in China existing is 5 billion m2 , power consumption is 70 to 300kwh/ m2 /year, excluding heating energy consumption equivalent to power 900 billion kwh/year. Moreover, in the China the development speed of large-scale public buildings is very fast, the annual increase is more than 50 million square meters, so the energy consumption of large public buildings will become a major growth point in the future energy consumption in many city. Therefore, in Chinese existing large public building energy conservation is facing severe challenges, but also has great potential. Kaifeng as a rapid rise of the Central Plains city, its current situation and characteristics of the energy consumption of large public buildings are regional representative strongly.

Instability of large-scale prototype Francis turbines of Three Gorges power station at part load

The rapid increase of renewable energies (e.g. wind and solar energies) requires hydroturbines (e.g. large-scale Francis turbines) to be operated at part load more frequently in order to improve the stability and flexibility of the power supply system. A device named as guide plate is currently being introduced into Francis turbines in order to shrink the size of the unit for the cost reduction. However, the effect of the guide plate on the instability of Francis turbines (especially at part load) is still an open question. This paper aims to elucidate the influence of the guide plate on the instability (e.g. in terms of large pressure fluctuation and its propagation) of the prototype Three Gorges turbines and its generation mechanisms. Computational simulations of the prototype Francis turbine have been performed and validated using on-site measurement. The results reveal that the addition of the guide plate induces an extremely low-frequency and high-amplitude pressure fluctuation at part load (e.g. guide vane opening 16°). This low-frequency pressure fluctuation initially generates in the draft tube, and then further propagates upstream (e.g. runner, guide vanes), acting as the dominant frequency. Our data analysis shows that the above pressure fluctuation is generated by the interactions between the vortex in the spiral casing induced by the guide plate and the swirling vortex rope in the draft tube.

Project Summary of Three Gorges' 840MVA Hydro-generator with Close-Loop-Self-Circulating Evaporative Cooling System

In December 2011 and July 2012, two sets of 840MVA Hydro-generator of Three Gorges on Yangtze River with Close-Loop-Self-Circulating Evaporative Cooling (CLSCEC) System were put into commercial operation. In this paper, we make engineering summary of these two generators with CLSCEC System. We also make a comparison between the internal water cooling (IWC) hydro-generator used in Three Gorges power plant and the CLSCEC hydro-generator in fields of their operating characteristics, working performances, technical features, working safety and reliability. In addition, engineering structures, type test results and systematic emulating calculation of CLSCEC schemes are analyzed.

Design of Pressure Fluctuation Measurement System for Hydro-Turbine Model Test

With the operation of giant unit of hydroelectric plant represented by the Three Gorges Power Station, the vibration problem of hydraulic turbine set unit is increasingly outstanding, especially the vibration of structure induced by pressure fluctuation. In order to guarantee the normal operation of unit, model test is more important in the respect of predicting performance, increasing stability and avoiding vibration. The pressure fluctuation measurement system based on LabVIEW according to pressure fluctuation model test was designed in this paper. The system is applied to the hydro-turbine model test-bed of HEC so that real-time automatic test with the characteristics of high stability and precision is implemented successfully. It plays an important role in respects of mastering the operation characteristics collecting and analyzing pressure fluctuation signals. Moreover it is meaningful to the hydraulic engineering.

Accuracy of the ultrasonic flow meter used in the hydroturbine intake penstock of the Three Gorges Power Station

Flows in large conduits are always difficult to measure. Ultrasonic flow meters developed in recent years are good for large flow conduits, especially for turbine performance testing in hydroelectric plants, because they are convenient to install, but then accuracy is difficult to estimate and there is no acknowledged estimation method when the installation requirements are not satisfied. The accuracy of the ultrasonic flow meter installed in the Three Gorges power station was analyzed both experimentally and with CFD analyses to analyze the effect of the complex flow field on the metering performance. A reduced scale (1:24) experimental system was built to study a series of cases, with the results showing that the flow error related to the complex flow field is about 0.3%. The penstock flow field of the Three Gorges dam was simulated, with the calculated flow error close to the experimental result. Analysis of the uncertainties in the experimental results and the Three Gorges flow meter measurement shows that the Three Gorges flow meter accuracy is better than 1%; thus the flow meter is sufficiently accurate for the turbine performance testing in the Three Gorges Power Station.

Analysis on the Generation Operation of the Three Gorges Reservoir during the Experimental Operation Period

The operation of the Three Gorges power station is of the most complex feature in China and even in the world, for it involves many factors such as flood control, power generation, shipping and water supply. This paper takes the experimental reservoir impoundment in 2008 for example, demonstrated its impact on power grid operation, meanwhile, put forward suggestions on impoundment time, impoundment target, impoundment and fluctuating process and adjusting mechanism building, etc.

Generation Control Scheduling Model of Three Gorges Power Station during Non-Abandon Water Period

With types of power units, huge installed capacity and complicated operation modes, the Three Gorges Power Station (TGPS) is very important in network operation of Yangtze River area. Power forecasting of TGPS plays an important role in protecting the power network operation and shipping, especially for the short-term output forecasting. The water consumption rate of power station is one of the key conditions in short-term generation control system during non-abandon water period. Therefore, in order to develop the generation control scheduling model of TGPS in non-abandon water period, analysis on many factors should be put including: hydraulic turbine characteristic curves of cascade hydropower stations constructed by TGPS and the Gezhouba Power Station; discharge at dam site; water stage of relationship between upstream and downstream; and the last element is tailrace effect from the Gezhouba Power Station to TGPS. The historical operating result shows that the model referred has wide application prospect in production practice for high precision and much exercisable.

Numerical Investigation of Guide-Plate Induced Pressure Fluctuations on Guide Vanes of Three Gorges Turbines

A new type of cavitation triggered by boundary-layer turbulence-production has been identified from the turbines of the Three Gorges Power Station. Our previous studies point out that the addition of the ‘guide-plate’ is responsible for the increase of the turbulence level (in particular the low-frequency mode) in the free-stream which in turn promotes the boundary-layer transition through receptivity mechanism. A new vortex structure identified from our numerical studies is revealed in this paper. It explains well how the free-stream turbulence is influenced by this new vortex structure which is created by the addition of this ‘guide-plate’. These results support one of the claims in the hypothesis proposed in our previous studies. The other claims in the hypothesis about the triggering mechanism of this type of cavitation in the boundary-layer are being verified through our on-going (numerical and experimental) studies. The numerical studies reported here are performed by using CFD simulations of the entire flow passage of the prototype turbine.

Numerical simulation of deformation in large scale hydroturbine blade casting

Deformation is one of the most common defects during the casting of large scale hydroturbine blades because of their curved three-dimentional (3D) surface geometry. Inverse deformation is usually applied to the pattern for sand moulds to finally obtain proper shape. However, the value of inverse deformation is hard to be determined. In this paper, a method is presented to determine the inverse deformation values by cycling numerical simulation. The inverse deformation is determined by the criteria of the achievement of even and appropriate machining allowance of the whole casting. This method is applied to a large scale blade casting used in the Three Gorges Power Plant. The calculated inverse deformation is obtained after three cycles. By using the electronic coordinate determination system (ECDS), its surface is measured and the machining allowance values of some points are acquired. The measured and calculated results are in agreement.

A NEW TYPE OF CAVITATION DAMAGE TRIGGERED BY BOUNDARY-LAYER TURBULENT PRODUCTION

A new type of cavitation damage has been observed on the turbines installed at the Three Gorges Power Station despite no cavitation detected during model tests. Metallurgical and fluid dynamic analysis suggests that this cavitation is triggered by boundary-layer turbulent production; the damaged (roughened) spot in turn triggers subsequent cavitation (damage) immediately down stream. This forms a sustainable dynamic process, resulting in long and equal-width streamwise damage-strips with spanwise regularity reflecting the spanwise stochastic characteristics of turbulent production. Owing to the heat effect of cavitation, intergranular corrosion takes place through sensitization process, leaving the damaged surface with a corrosion appearance. Also, bluing presents at the damaged tails, owing to the nature of low-intensity damage. Extremely large turbines are much more susceptible to this type of cavitation (damage) owing to the similarity laws currently employed for turbine development not concerning the freestream turbulence and the boundary-layer dynamics.

Current Status of Welding Technology & The State Key Lab of Welding in China

In the near twenty years, with the rapid increase of Chinese economy, Chinese welding technology developed very fast. In 2003, the annual output of steel in China has reached 230 megatons and above 40 percent was manufactured by welding process. The main welding engineering projects include: the Three Gorges power station, bridges over the Changjiang River, high pressure heavy-duty chemical container, pipeline project of transferring natural gas from West to East and manned spacecraft etc. Meanwhile, Chinese annual output of welding materials exceeds 1,200 kilotons, welding equipments exceed 200,000 sets and the welding automation rate reached 40 percent. The State Key Laboratory of Advanced Welding Production Technology in Harbin Institute of Technology is the only welding laboratory of national level in China. It is the base of applied fundamental research and high quality welding technicians training. It has completed many projects of welding technology development and some significant applied engineering tasks. Every year, about 15-20 Doctors, 40-50 Masters and 70-100 Bachelors graduate from the Laboratory. Also, it is opened to the whole world.

Impact of new technology on China's power system

China is a developing country. With the move towards deregulation and opening markets, there have been many changes in the industrial and technical sector, especially in the power industry. The changes penetrate into generation, transmission, and distribution systems. With development of the Three Gorges project started in the 1990s, many studies and test projects have been carried out to determine the type of transmission lines, automation devices, etc. The progress associated with the Three Gorges power system, compact lines, and distribution automation is summarized.

Current Status and Prospects of Power System Development in China

Over the past five to 10 years, electric power and power systems in China have developed rapidly. The total installed generation capacity at the end of 1996 reached about 230GW with annual production Of around 1,070 TWh, which is ranked the second in the world. There are now six inter-provincial power networks and five independent provincial networks in operation in mainland China. The Three Gorges Hydro-Power Project is now entering a important phose of construction ond a large amount Of preparation work have been completed for the construction Of the Three Gorges Power Transmission System. The total number of 26 sets Of generators for the Three Gorges Power Plant will be completely installed before the year 2010. By the year 2020, the interconnection Of the power networks of the Whole country will beformed based on the interconnection between the Three Gorges Power System and other inter-provincial power networks.