Journal of Hydroelectric Engineering

水力发电学报

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2021 Vol. 40, No. 8 Published: 2021-08-25

	1	Advances on key technologies of spot bidding for hydropower ^Hot!
		MA Guangwen, ZHANG Yongfeng
		DOI: 10.11660/slfdxb.20210801
		The spot market of power is an important part of the modern power system, which plays a key role in restoring the properties of power commodity, finding its prices, and optimizing its resource allocation. Hydropower is often affected by the randomness of river runoff, which results in prominent contradiction between the high water and low water and great output uncertainty. Operation of a reservoir is usually limited by its comprehensive utilization, the power stations of a cascade system are mutually connected closely, and information sharing between upstream and downstream multi-agent power stations is difficult. In addition, external transmission channels are lacking and section blocking is severe. Thus, hydropower participation in the electricity spot market is facing many challenges. This paper summarizes the research status quo in China and abroad, focusing on the mathematical models and algorithms previously developed and the pros and cans of the existing methods. We also discuss the trends of hydropower spot market development in the future, including the key scientific and technological problems involved in "quantity price" declared in the spot market: prediction of market clearing prices, optimization of power generation capacity, bidding strategy, and the decision support system of hydropower spot quotation. This would help enrich the theory and method of power spot market and improve the production and operation of hydropower enterprises.
		2021 Vol. 40 (8): 1-11 [Abstract] ( 193 ) PDF (613 KB) ( 711 )

	12	Study on risk analysis of Sanhekou Reservoir operation based on different water demand processes
		BAI Tao, YU Jia, WEI Jian, HUANG Qiang, WU Lianzhou, MA Rong
		DOI: 10.11660/slfdxb.20210802
		Aimed at the risk problem in reservoir operation caused by uncertainty in water demand process, this study examines the risk of reservoir water supply operation. Based on the initial dispatch mode of the Sanhekou Reservoir, we develop a risk indicator system and a dispatch model for annual average water shortage minimization, and solve it using an improved flower pollination algorithm (IFPA). A four-dimensional coordinate system is constructed and used in analysis of the risks of different reservoir operation schemes. Results indicate IFPA has strong optimization ability and stability in solving the long-term scheduling model. And for water supply risk, the most unfavorable scheme is the water demand process scheme 3 based on the frequency of high-low water encountering, with annual reliability as low as 0.64 and a water shortage index of 2.35, showing a water shortage of several successive years. The values of risk indicators significantly depend on time scale, the smaller the time scale, the greater the risk, the more unfavorable to the scheduling results. The results demonstrate new ideas for accessing reservoir water supply operation risk, and also provide important reference for reservoir management and planning departments.
		2021 Vol. 40 (8): 12-22 [Abstract] ( 151 ) PDF (672 KB) ( 460 )

	23	Study of circulation elimination and optimization for side inlet/outlet and adjacent cofferdams
		GAO Xueping, XU Tianhao, ZHU Hongtao, SUN Bowen, CHEN Siyu
		DOI: 10.11660/slfdxb.20210803
		After the construction of the side inlet/outlet of a pumped storage power station is completed, usually the adjacent cofferdams cannot be dismantled completely, leaving the cofferdam residues in situ. At low operating water levels, adverse circulations are likely to form in the surface layer of water flows in front of the inlet/outlet under the influence of residual cofferdams and topography, and tend to cause large water surface fluctuations in outflow mode or induce harmful vortices above the inlet/outlet in inflow mode. This paper explores effective measures to improve flow patterns around a side inlet/outlet and cofferdam residues, using the computational fluid dynamics method in a case study of the Weifang pumped storage power station. To avoid the circulation, we modify and optimize the cofferdam slope and its bottom edge location, and compare and verify the effect of different schemes against the measurements on a physical model. The results show that when residual cofferdams exist in front of a side inlet/outlet, flow patterns at the water surface in the reservoir area are usually stable in inflow mode, but an adverse circulation is very likely to form around the cofferdams in outflow mode and it cannot be avoided by adopting a symmetrical design of the cofferdams. When the cofferdam’s slope bottom edge is along the direction of the diffusion flow in the open channel section, the flow spreads smoothly and evenly into the reservoir area, greatly improving the flow conditions.
		2021 Vol. 40 (8): 23-33 [Abstract] ( 152 ) PDF (4645 KB) ( 313 )

	34	Effects of diverting flow on urban streets on flow pattern transition
		JIANG Chunbo, ZHOU Qi, SHEN Yanxia, LIU Gaofei, DUAN Yanhua
		DOI: 10.11660/slfdxb.20210804
		With accelerating urbanization and aggravating global climate changes, urban flood disasters occur frequently. It is theoretically and practically of great significance to study the characteristics of flood discharging on urban streets and grasp the mechanism of how it is influenced by urban buildings. This study has conducted a series of physical model tests focusing on the influence of urban buildings on flood water movement, arranging water outlets on both sides of the main street to simulate lateral flow diversion between the buildings of discontinuous distribution. For the main street flood flow, the influence of the outlet locations on its pattern transition is analyzed; a detailed observation and analysis are made on the dynamics of the transition from supercritical to subcritical flow and its responses to changes in upstream inflow and diverting outlet locations. We find the parameters of the hydraulic jump－such as jump location, jump form, roller length, conjugate depth ratios, and discharge ratio－behave quite differently from those of the classical hydraulic jumps.
		2021 Vol. 40 (8): 34-42 [Abstract] ( 86 ) PDF (1033 KB) ( 352 )

	43	Experimental study on staged sedimentary evolution of lacustrine delta
		XIN Weiyan, BAI Yuchuan, LIU Wanli, ZHANG Mingjin
		DOI: 10.11660/slfdxb.20210805
		Formation and evolution of an estuarine delta is an important part of river evolution and river geomorphology development. We conduct a laboratory experiment of a lacustrine delta controlling its upstream water and sediment inflows and downstream water level, and study its staged sedimentary evolution under periodic water and sediment inflows, focusing on the responses of its evolution and channel system development to the inflow variations and on the feasibility of laboratory-scale modeling of its staged evolution. This scale model is used to simulate the upper and lower reaches of the Ganjiang delta, and its design satisfies the similarity of water flow and sediment movement. The results show that the measured features of staged delta evolution are similar to the field observations, and it is reasonable and feasible to simulate in laboratory the evolution trends of lacustrine deltas under natural conditions through using different stages and controlling in each stage the water and sediment inflows and the lake water level.
		2021 Vol. 40 (8): 43-56 [Abstract] ( 119 ) PDF (5525 KB) ( 422 )

	57	Simulations and analysis of speed rising of variable-speed pumped storage units under large disturbances
		ZHOU Xijun, DING Jinghuan, HUANG Yifan, YANG Weijia, YANG Jiebin, YANG Jiandong
		DOI: 10.11660/slfdxb.20210806
		Variable-speed pumped storage technology has become an emerging development and research direction in pumped storage industry in recent years, and research on the dynamic characteristics of variable-speed pumped storage power plants (VSPSPs) is of great significance. This paper focuses on the hydraulic-mechanical subsystem of a VSPSP and analyzes the rising trends of its unit speed during load rejection transient process, by using a nonlinear integrated model. We verify the correctness of the model by comparing its simulation results under load rejection against the on-set measurements of a real power station, analyze the dynamic response and speed rising of the unit under load rejection at different initial speeds, and find the speed rising can be explained through its momentum conversion mechanism and torque characteristic. The results demonstrate that under load rejection, if the initial speed of the variable-speed unit increases in a certain range, the maximum speed will not grow significantly, and there still exists a certain safety margin from the maximum allowable speed.
		2021 Vol. 40 (8): 57-64 [Abstract] ( 183 ) PDF (1204 KB) ( 531 )

	65	Fish-friendly turbine with two counter-rotating runners. Concepts and runner optimization
		ZHANG Pengcheng, HU Dongliang, CHENG Yongguang, TAI Rong
		DOI: 10.11660/slfdxb.20210807
		While hydropower projects bring many positive benefits to people, they also produce some negative ecological effects like cutting off fish migration channels. To alleviate such side effects, fish-friendly turbines have attracted great research attention in recent years. This paper presents a new fish-friendly turbine for run-of-river hydropower plants. Aimed at reducing pressure gradients to obtain low fish casualties, this turbine has three major features: fewer spiral blades with long blade passages, better for lowering its fish hitting probability; two counter-rotating runners, better for lengthening its flow passage and improving its generating efficiency; all its blades satisfy the optimal conditions of velocity triangles at the blade inlet and outlet, better for even and smooth distributions of velocity and pressure. CFD simulations show that its generating efficiency can reach up to 80.4% and its pressure gradient is better than the existing fish-friendly standard recommended by international scholars.
		2021 Vol. 40 (8): 65-72 [Abstract] ( 161 ) PDF (1473 KB) ( 472 )

	73	Wave tracing method for calculation of water hammer in pump stations
		ZHANG Runqiang, DONG Jiaxin, ZENG Zongyao, WANG Yuchuan, YANG Jianguo
		DOI: 10.11660/slfdxb.20210808
		A wave tracking method (WTM) for hydraulic transients in a pump-pipe system is derived to solve the equations of water hammer and its bridging in the water column separation case; similarities and differences between this method and the Eulerian fixed-grid method of characteristic (MOC) are compared and discussed in theory, solving procedure, and calculation accuracy. Calculations in two study cases show that theories of the two methods are the same fundamentally but WTM directly calculates the pressure wave (plus head differences in the initial value). WTM calculations are completely consistent with MOC when friction loss is not considered, indicating our equations, boundary conditions, and bridging method for the system with column separation are effective and satisfactory. Even in the cases of friction loss considered, a difference less than 0.3% is revealed between the two methods that share virtually the same accuracy. This slight difference is caused by the treatment of the friction loss term. And both share the same max and min values of transient parameters for water column separating and bridging. For a large-scale pipeline or pipe network system, WTM can directly calculate its hydraulic transients from the boundary conditions, with no need of the numerical algorithms as adopted by MOC, thus enjoying a higher computational efficiency.
		2021 Vol. 40 (8): 73-83 [Abstract] ( 195 ) PDF (1256 KB) ( 310 )

	84	Numerical simulation of rubber membrane penetration depth in triaxial tests of coarse-grained materials
		PAN Hongwu, WANG Wei, LI Na, ZHANG Bingyin
		DOI: 10.11660/slfdxb.20210809
		Rubber membrane penetration can cause significant errors in volumetric deformation measurement in the triaxial test of coarse-grained materials. Considering the characteristics of particle contact, this paper presents an efficient algorithm for detecting particle contact state based on the particle surface that is reconstructed using the Nagata patch method. We simulate particle-membrane contact using a dual mortar method and a large geometric deformation algorithm, and modify the particle-membrane film distance based on the particle surface reconstruction. Hence, refined simulation of particle-membrane contact is realized and the penetration process of a flexible rubber membrane can be calculated. Simulations are carried out to study the membrane penetration processes in Kramer’s steel ball test, coarse-grained triaxial test, and standard coarse sand triaxial test. The calculation results are consistent with the general rules and agree well with the test results, indicating that our method is applicable to simulation and analysis of the membrane penetration process of coarse-grained particles.
		2021 Vol. 40 (8): 84-92 [Abstract] ( 127 ) PDF (2528 KB) ( 383 )

	93	Study on early strength and micro-pore characteristics of hydraulic concrete with mineralized microorganisms
		MENG Yongdong, WANG Dingjie, CAI Zhenglong, TIAN Bin, DING Yi, HE Zhuqing
		DOI: 10.11660/slfdxb.20210810
		Microbial-based self-repair of concrete cracking is a research hotspot in China and abroad in recent years. This study uses Bacillus Coriolis as the mineralizing microorganism and lactic acid calcium as a nutrient to study the effect of mineralizing microorganisms on the early compressive performance and microscopic pore characteristics of hydraulic concrete. We conduct compressive tests on the concrete with different microbial concentrations, and observe the variation trends in compressive strength. Nitrogen adsorption and scanning electron microscopy are adopted to study microscopically the effects of microbes on pore water, microporous structure, and micro morphology of industrial concrete. The test results show that the compressive strength can be significantly improved by mixing microorganisms; with the increase in microorganism concentration, it shows a trend of increasing first sharply and then mildly. It has a peak at the microorganism concentration of 9.8×107cells/cm3 after an increase in the 28 d strength by 13.1%. Our microscopic observations reveal the microbes can effectively elevate the density and its uniformity of hydraulic concrete cement paste and improve the internal structure, thus significantly raising the compressive strength of the concrete mixed with mineralized microorganisms.
		2021 Vol. 40 (8): 93-99 [Abstract] ( 130 ) PDF (1338 KB) ( 379 )

	100	Intelligent control method of temperature stress and transverse joint behaviors of concrete arch dams
		MA Rui, ZHANG Qinglong, HU Yu, AN Zaizhan, YIN Tao, LI Qingbin, HUANG Dahai, MA Jingang, HUANGFU Zehua
		DOI: 10.11660/slfdxb.20210811
		Preventing temperature cracks and regulating the working behaviors of transverse joints are two crucial issues in arch dam construction, and a reasonable cooling strategy is key to an effective solution. This paper describes a new intelligent method for controlling temperature stress and transverse joint behaviors and the application of its control concept, simulation analysis tools and automatic control technology, and develops an intelligent control system of arch dam construction. Analysis shows this system effectively controls the dam body stress and the working behaviors of transverse joints and gives full play to the performance of concrete materials, greatly improving construction efficiency. We have achieved the optimization goal of intelligent temperature crack control and intelligent transverse joint behavior adjustment.
		2021 Vol. 40 (8): 100-111 [Abstract] ( 177 ) PDF (1219 KB) ( 744 )

	112	SD-DES coupling model for construction schedule rectification of underground hydropower stations
		ZHAO Mengqi, YU Jia, REN Bingyu, WANG Xiaoling, LV Fei, TONG Dawei
		DOI: 10.11660/slfdxb.20210812
		Construction schedule rectification is an effective method to ensure the orderly construction of underground hydropower stations against the interference of emergencies, and its process can be effectively simulated using a system dynamics (SD) model. Previous studies lack consideration of rectification strategies adopted in the construction, and the reported SD models failed to consider rectification parameters. This study constructs a SD-DES model by coupling a SD model and a discrete event simulation (DES) model for construction schedule rectification, considering rectification parameters and integrating four sub-models into the SD: overtime, increase in mechanical equipment, increase in construction personnel, and rescheduling. Taking the advantages of the SD and DES models, we simulate and analyze the full procedure of schedule estimation - rectification strategy formulation - strategy implementation effect. Application to a real underground hydropower station project shows that our new model improves significantly the schedule rectification strategy, more superior to the traditional SD model.
		2021 Vol. 40 (8): 112-123 [Abstract] ( 117 ) PDF (2317 KB) ( 245 )

	124	Temperature-confining pressure coupled creep model of sandstone in diversion tunnels
		ZHANG Mingzhu, LI Huiqin, YAN Xiangzhi
		DOI: 10.11660/slfdxb.20210813
		Creep characteristics of deep surrounding rock under the coupling effect of high temperature and confining pressure is studied by conducting triaxial creep tests on sandstone under different temperatures using the rock test system MTS815.02. We consider the influence of temperature, confining pressure, and time on these characteristics, and assume an exponential decay form for the relationship of temperature, confining pressure and time versus damage variables. Then, we develop a new time-dependent creep model that, coupling rock temperature and confining pressure, is equipped with non-constant creep parameters obtained through improving the Nishihara model. The results show the strain-stress curves and time-dependent strain curves at different temperatures are all in good agreement with measurements. This new model not only better describes attenuation creep deformation and stable creep deformation, but better reflects deformation characteristics in the accelerated creep stage. And it verifies the significant influence of temperature, confining pressure and time on rock creep characteristics.
		2021 Vol. 40 (8): 124-131 [Abstract] ( 120 ) PDF (502 KB) ( 457 )

	132	Damage characteristics analysis of gravity dam subjected to pulse-type ground motions
		ZHAI Yafei, ZHANG Liaojun, CUI Binghui, BI Zhonghui, ZHANG Hanyun
		DOI: 10.11660/slfdxb.20210814
		Previous studies have shown pulse-type ground motions have a significant impact on structure seismic safety, but few focused on the overall dynamic damage characteristics of concrete gravity dams under such motions. Based on the Koyna gravity dam project, this study develops a multi-coupling simulation model that can describe satisfactorily the dynamic damage evolution process of its dam concrete and dam foundation rock mass. We select ground motion records of pulse and non-pulse types from the strong earthquake database NGA-West2, and simulate and analyze its response spectrum characteristics. From the simulations, the damage areas, energy consumption, displacement responses, and other overall damage evolution characteristics of the dam body are examined in detail. The results show that pulse ground motions pose a significant impact on the overall damage to the dam body and its foundation, and can cause greater energy dissipation and stronger displacement responses of the structure system. After the ground motions, the residual deformation of the dam subjected to pulse-type ground motions is obviously larger in the dam’s head part than that of the non-pulse type, but it shows little effect in the lower part.
		2021 Vol. 40 (8): 132-140 [Abstract] ( 123 ) PDF (1489 KB) ( 455 )