Hydroelectric units generally use Babbitt Alloy with strong friction reduction properties as the bearing bush material. However, due to the bearing bush made by Babbitt Alloy material has lower strength, it can not be used in the need to withstand the larger pressure of large-scale hydropower generating sets. The Steel Kogu (SK) can withstand large loads while having good wear resistance. Therefore, the oil film temperature, bearing bush body temperature and power of SK bearing pad and Babbitt Metal bearing bush are studied comparatively through experiments. The thickness, pressure, maximum temperature of oil film, base deformation and power loss of the two types of bearing bush are studied comparatively by numerical calculation. The results show that at the same oil inlet temperature, the base deformation and maximum oil film temperature of SK bearing bush are lower than that of Babbitt Alloy by 0.06-0.08 mm and 9.6-14.6 ℃, respectively, and the oil film thickness of SK bearing bush is higher than that of Babbitt Alloy by 13-15 μm. The SK bearing bush can be used as a potential choice of bearing bush material for large-scale hydroelectric units because of its lower oil film temperature and smaller base deformation during the operating process.

Unsteady friction plays a very complex role in the water hammer phenomenon within pipeline systems. For hydropower station with super-long headrace tunnel (SLHT), it is crucial to consider the effects of unsteady friction adequately. This paper conducts a study on the nonlinear transient response characteristics of hydropower station with SLHT based on unsteady friction. Firstly, a system model of hydropower station with SLHT is established using the method of characteristics, incorporating unsteady friction based on instantaneous acceleration. Then, simulations of this model are performed under load and frequency disturbances. Finally, the stability of the model under frequency disturbances is evaluated using the Bode plot method, and the impact of unsteady friction parameters on system stability is investigated in conjunction with the energy equation. The results show that the unsteady friction in the pipeline primarily affects the rapid response phase of the water turbine in the hydropower station with SLHT. When the impact coefficients of local acceleration (k_t) and convective acceleration (k_l) increase, the system stability deteriorates. Moreover, changes in k_t and k_l make the system more sensitive to high-frequency disturbances.

In order to further improve the control performance of water turbine, a control strategy based on the adaptive chaotic particle swarm optimization variable domain fuzzy PID (CAS-PSO-VFPID) was proposed for the turbine regulation system. Firstly, a model of nonlinear hydraulic turbine regulation system was established, and a variable domain fuzzy controller was constructed according to the system model. Then, the adaptive chaotic particle swarm optimization (CAS-PSO) was used to optimize and design the variable domain fuzzy controller, and the CAS-PSO-VFPID controller was obtained. Finally, the applicability of the nonlinear turbine regulation system model was verified by simulation. The multiple control strategies under different working conditions were compared and simulated with Whale Algorithm Optimization Variation Domain Fuzzy PID (WOA-VFPID), Standard Particle Swarm Optimization PID (PSO-PID), Standard Particle Swarm Optimization Optimization Variable Domain Fuzzy PID (PSO-VFPID). The simulation results show that the system convergence speed and optimization ability of the CAS-PSO-VFPID control strategy are fast, which can effectively improve the response speed and accuracy of the hydraulic turbine regulation system, and make the system have better dynamic stability.

With the increasing proportion of new energy, the inertia support, voltage support, and frequency regulation ability are obviously weakened in current power system. The development of energy storage system with synchronous condenser and flywheel (ESSSCF) is of great significance to improve the regulation capability of new energy power generation and enhance the stability of new power systems. This article briefly describes the principle and different operation states of the magnetic-geared speed regulator (MGSR) for ESSSCF, and focuses on the design optimization of its electromagnetic structure. The electromagnetic finite element model of the MGSR is established. The shape of the flux barrier is selected for the inner rotor with V-shaped permanent magnet by calculating and analyzing the no-load leakage flux factor. The geometric parameters of the V-shaped permanent magnets and stator slots and the pole-arc coefficient of the modulating ring are optimized for multiple objectives, respectively, using genetic algorithm, under the conditions of a constant amount of permanent magnet and a constant area of stator slot. In addition, the correlation of the target performances with the geometric parameters is analyzed. The results of the design optimization and correlation analysis can direct the structural design of the magnetic-geared speed regulator for improvement of the torque and efficiency performances.

The tailwater level of hydropower station is a critical parameter for calculating the unit's output. When influenced by the downstream reservoir's backwater effect, discrepancies often arise between the designed tailwater curve and the actual observed values, leading to increased errors in the output-flow calculations. Utilizing the latest historical observation data, this study explores the relationship between the tailwater level of BHT Hydropower Station, its discharge, and the water level of the downstream XLD Reservoir. A Bayesian optimized long short-term memory (BO-LSTM) prediction model is developed based on multi-scenario analysis. The applied effect is analyzed under conditions of peak load and flood discharge. The results indicate that when the water level of XLD exceeds 585 meters, the tailwater level of BHT Hydropower Station is significantly influenced. Compared to the nonlinear curve fitting method, the BO-LSTM model based multi-scenario analysis demonstrates a substantial improvement in accuracy, with an average absolute error (M_MAE) reduced by 68.1%. The BO-LSTM model more accurately captures the fluctuations and changes in water levels under various operating conditions. The research results have important significant for refined operation of hydropower stations.

Aiming at the optimal dispatching problem of cascade hydropower stations in the lower reaches of the Jinshajiang River during the drawdown period, based on the analysis of the reservoir water balance, water level, discharge flow rate, and unit output, a daily-scale refined scheduling model was established by maximizing the total power generation of cascaded reservoirs and considering the actual scheduling requirements. The model was solved using the DPSA-POA algorithm. The effectiveness of the model and solution method was verified by the actual case. The results show that the proposed scheduling model can make full use of water resources and maximize the power generation in the drawdown period under the premise of ensuring the safe operation of each reservoir. Thus, it provides theoretical basis and technical support for the refined scheduling management of the cascaded reservoirs.

The Longyangxia and Liujiaxia Reservoirs in the upper reaches of the Yellow River have annual regulation capacity and undertake comprehensive utilization tasks such as flood control, water supply and irrigation, and power generation in the Yellow River Basin. The coordination and consistency of multiple objectives need to be achieved by constructing a multi-objective optimized dispatching system for cascade reservoirs. A multi-objective scheduling model has been established for the Longyangxia-Liujiashan cascaded reservoirs, with the goals of maximizing the peak shaving rate, total power generation, and average sediment flushing ratio. The model is solved using the NSGA-Ⅲ algorithm, and an analysis is conducted regarding the competitive relationships among the objectives of flood control, power generation, and sediment flushing. The established multi-objective optimization scheduling scheme is further evaluated through a developed indicator system, and the TOPSIS method is applied to optimize the set of scheduling solutions. The results show that there is a significant competitive relationship between the objectives of power generation and flood control; No significant competition exists between the objectives of sediment discharge and flood control, and there is some competition between the objectives of sediment discharge and power generation. Through a comparison of the optimal scheme and the actual scheduling data, it can be seen that the benefits of flood control, power generation, and sediment discharge in the optimal scheme increased by 20.89%, 16.02%, and 3.61%, respectively, compared to the actual scheduling.

With the construction and operation of integrated clean energy bases, there is an urgent need for multi-energy joint dispatch. On the basis of cascade hydropower joint scheduling, this article embeds the risk of channel electricity curtailment as a penalty constraint, integrates the working experience of scheduling personnels with rolling ideas, and explores a method for formulating multi-time scale cascade hydro-photovoltaic complementary joint scheduling rules based on actual operation. The potential risks of power abandonment is identified in advance and control measures are proposed. By selecting the benefits of hydroelectric power generation and energy storage, as well as photovoltaic power generation, a complementary function of hydro-photovoltaic joint system is established to evaluate the scheduling rules. The proposed method has been applied to the hydro-photovoltaic complementary system of Xiaowan and Manwan on the Lancang River. The results show that the economic benefits of the hydro-photovoltaic joint system is significantly increased without significantly affecting the hydropower regulations. The idea has the feasibility of promoting the joint operation of the integrated hydro -photovoltaic energy storage and clean energy watershed base in future.

To explore temporal and spatial variations of extreme precipitation in the Rolling Hilly Region of Northeast China, a set of extreme precipitation evaluation indicators was established using the daily precipitation data from 79 meteorological stations covering the period from 1981 to 2015. The intensity, frequency and persistence of extreme precipitation were analyzed using various methods, including linear trend estimation, coefficient of variation, Mann-Kendall test, R/S analysis, and GIS spatial analysis. The results show that from 1981 to 2015, the overall extreme precipitation showed a weakening trend in the Rolling Hilly Region of Northeast China; R×1day, R×5day, R12D, R50D, and CRED decreased at rates of -0.5 mm/10a, -2.1 mm/10a, -0.2 d/10a, 0.02 d/10a and 0.03 d/10a, respectively. The inter-decade variation of the intensity index showed a state of "rise-fall-rise", and the annual change of frequency index and persistence index showed a "fall-rise" form, which increased by 12.5%-15% in the 2010s compared with the 2000s. The C_V value of frequency index R50D is 0.45, which fluctuates sharply, and the C_V value of other indices is less than 0.2, and the fluctuation range is small. R50D and CRED experienced abrupt changes in 1988 and 1990, respectively, and exhibited an increasing trend before the mutation points and a weakening trend after that. Extreme precipitation increased during the 1990s, weakened in most areas during the 2000s, and intensified in both frequency and intensity in the northern high-altitude areas of the Rolling Hilly Region of Northeast China in the 2010s, while it reduced in the Southern Regions. This study can provide a theoretical basis for formulating strategies to cope with extreme precipitation risks in the Rolling Hilly Region of Northeast China.

Studying the propagation of meteorological drought to hydrological drought is essential for meteorological information-based drought management and hydrological drought warning systems. Taking the Ganjiang River source basin as an example, this paper uses the basin's monthly meteorological and hydrological data for the past 60 years to study the propagation pattern of meteorological drought to hydrological drought, and explores the differences in drought propagation among sub-basins. The results show that the propagation of meteorological drought to hydrological drought has various ways, with a one-to-one correspondence; The drought events increase hazards after propagation from meteorology to hydrology; The Logistic model can better reflect the response relationship of hydrological drought characteristics to precipitation shortage conditions; The large reservoirs have a significant effect on the drought resistance of the basin.