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Wind curtailment, caused by wind power uncertainty, has become a prominent issue with the large-scale grid connection of wind power. To fully account for the uncertainty of wind power output, a short-term hydro-wind-thermal operation method based on a wind power confidence interval is proposed. By utilizing the flexible start-stop and efficient ramp-up of cascade hydropower plants to smooth fluctuations in wind power output, a multi-objective optimal scheduling model that minimizes the cost of power generation and maximizes the consumption of clean energy is constructed. To reduce the solution's complexity, we chunk the model according to the energy type using a hierarchical solution. The overall solution framework, which integrates a nonparametric method, a heuristic algorithm, and an improved particle swarm algorithm, is constructed to solve the model rapidly. The simulation results of a regional power grid show that the proposed method can attain an efficient solution in 83.5 seconds. Furthermore, the proposed method achieves an additional 455,600 kWh of hydropower and a reduction of ¥233,300 in the cost of coal consumption. These findings suggest that the proposed method is a good reference for the short-term operation of a hydro-wind-thermal combination in large-scale wind power access areas. [ABSTRACT FROM AUTHOR]

The water consumption rate for hydropower station power generation is an important index of the economic operation of hydropower stations, which has been widely considered and applied in the production practice of hydropower stations and has great significance for the full utilization of hydroelectric resources. This paper takes A and B cascade hydropower stations as the research objects to study the variation patterns of the water consumption rate of hydropower stations under different conditions, which mainly includes the following: (1) in this study, the relationship curve of output–gross head–flow (NHgrossQ) of each unit was established based on the relationship curve of output–net head–flow (NHQ) and the flow–head loss curve of each unit; (2) the mirror vertical shift method was used to calculate and plot the relationship curve of gross head–flow for combinations of multiple units; (3) the outflow–water–output characteristic curve of the hydropower station under the conditions of different reservoir water levels, different discharge flow, or different power generation output under the optimal operation of the hydropower station were calculated and drawn; (4) the outflow–water level–output curve of the hydropower station under various conditions was converted into an outflow–water level–water consumption curve; (5) the variation characteristics of the water consumption rate of the hydropower station under different conditions were analyzed; (6) on the basis of the definition of the water consumption rate of cascade hydropower stations, the research on the variation in the water consumption rate of cascade hydropower stations was carried out under the conditions of different water levels of the A reservoir, different water levels of the B reservoir, different discharge, and different total output of the hydropower stations. The variation pattern of the water consumption rate of hydropower stations under different conditions obtained in this paper can provide technical support for the real-time economic operation of cascade hydropower stations. [ABSTRACT FROM AUTHOR]

With the large-scale integration of new energy into the grid, there is an urgent demand for peak-shaving resources in the power system, and it is urgent to comprehensively improve the utilization level of flexible power sources in the power system to maintain the safe and stable operation of the power grid and improve the efficient of clean energy consumption. As a regional power grid with the highest proportion of new energy grid-connected in China, the Northwest Power Grid is affected by the factors of few newly installed coal power plants in recent years, the pumped storage power plant has not been put into operation on large scale, and the scale of electrochemical energy storage is insufficient. In a word, the insufficient flexible resources restrict the efficient use of new energy. In this paper, by exploiting the role of cascade reservoirs that have been put into operation on Upper Yellow River, and further excavating the peak regulation potential of cascade hydropower stations, it can achieve the effectiveness that is similar to energy storage and effectively save the construction cost of peak regulation resources. By establishing a comparison model, three scenarios of cascade hydropower not participating in peak shaving, direct hydropower participating in peak shaving, and cascade hydropower participating in peak shaving were analyzed, and the positive contribution to the grid peak shaving resources under the mode of participating in peak shaving was verified. [ABSTRACT FROM AUTHOR]

A data‐driven multi‐time scale robust scheduling model for a wind–hydro–thermal power system is presented in this study, according to the characteristic that wind power prediction accuracy increases with the decrease of the time scale. In day‐ahead scheduling, a generation plan is formulated with the target of minimising the total operating cost, and a data‐driven robust optimisation method based on the robust kernel density estimation (RKDE) is employed to deal with the uncertainty of wind power. That is, the distributional information of wind power is extracted by the RKDE from the big data, then the distributional information is incorporated into a data‐driven uncertainty set, and finally, a robust optimisation model is formed. During the intraday scheduling stage, the objective is to minimise the total water spillage in cascade hydropower stations and the adjustment cost of thermal units, and the task is to readjust the outputs of units based on the base outputs obtained by the day‐ahead scheduling, combined with the rolling forecast data of wind power and load. The real‐time scheduling is aimed at satisfying the power balance with minimum power adjustment. Finally, a test system is carried out to verify the efficiency and practicability of the proposed framework. [ABSTRACT FROM AUTHOR]

[Display omitted] • A vibration avoidance strategy considering the multiple vibration factors is proposed. • The influences difference of wind and solar energy on hydropower units are analyzed. • The planned output schemes of cascade hydropower station are presented. The cascade hydro-wind-photovoltaic complementary generation system is considered to be an effective approach to solve the output fluctuation of renewable energy. However, for hydropower units, grid-connected operation results in frequent power adjustments and increases the risk of operating in vibration zones, which may lead to the low generation efficiency and hidden danger for the power plant. This study proposes a vibration avoidance strategy based on the unit commitment while considering multiple vibration factors. Multi-objective optimization is performed to minimize the water consumption, the number of times crossing the vibration zone and the number of units involved in regulation. Results for a case study located in the Southwest China, indicate that the proposed strategy avoids hydropower units operating in the vibration zone (the vibration rates decrease from 7.6%, 6.7%, 6.3% to 0 under three initial water levels). Comparing 9 scenarios with different meteorological conditions, indicates that photovoltaic power enables less hydropower units to complete the peak load regulation and to cross the vibration zone less frequently due to PV daily generation profile fitting better the load curve, unlike wind power. Finally, the operation schemes of cascade hydropower station in different periods are proposed. The suggested models are beneficial in reducing the impact of the vibration on hydropower units in hybrid power system and provide operation strategy for cascade hydropower station. [ABSTRACT FROM AUTHOR]

The uncertainty of electricity demands and reservoir inflows makes the optimal operation of hydropower stations extremely difficult. Therefore, it is very important to establish a multi-time-scale coupling model that not only reflects the current inflows of short-term strategies but also adapts to the mid-term and long-term optimal strategies. In this paper, using the Three Gorges and Gezhouba cascade hydropower stations as examples, the principles of the layered coupling on multiple time scales are proposed. The control strategies and mechanisms of information feedback for layered models are also presented. Based on these theories, this study establishes an optimal five-layered coupling operation model of the Three Gorges and Gezhouba cascade hydropower stations with the objective of maximizing the generated energy solved by Incremental Dynamic Programming (IDP). Data from 2009 is used as the case study for the optimization of the cascade system. The results show that the model can preferably take advantage of the forecasted inflows with different levels of precision and coordinate the "control and feedback" relationships between short-term and long-term strategies. [ABSTRACT FROM AUTHOR]

Yi, M.; Mo, L., and Shen, Q., 2020. Study on generation scheduling of cascade hydropower stations based on SAPSO. In: Guido Aldana, P.A. and Kantamaneni, K. (eds.), Advances in Water Resources, Coastal Management, and Marine Science Technology. Journal of Coastal Research, Special Issue No. 104, pp. 371–378. Coconut Creek (Florida), ISSN 0749-0208. With the reduction of energy and the reform of China's electric power system, it is of great help to develop clean energy such as hydropower to ease the lack of energy. Many methods are studied to solve the reservoir optimal scheduling problem, such as particle swarm optimization (PSO). In order to solve the premature problem and slow convergence of traditional PSO, simulated annealing particle swarm optimization (SAPSO) is proposed in this paper. The algorithm is improved by adding shrinkage factor and combining with simulated annealing algorithm. Establishing the maximum generation model, and SAPSO algorithm is used to optimize the power generation scheduling of four and ten hydropower stations. The case study shows that the application of SAPSO to solve the short-term optimal scheduling problem of cascade hydropower stations has achieved satisfactory results in effect and rationality. It provides a reliable method for the optimal operation of cascade hydropower stations. [ABSTRACT FROM AUTHOR]

Due to the volatility of natural resources, the power fluctuations of photovoltaic (PV) generation have serious negative impacts on the power quality. This paper reports a novel approach to resolve this problem in a combined cascade hydro-PV-pumped storage (CH-PV-PS) generation system through appropriate power distribution on a small time scale. According to the characteristics of power generation systems and multi-constraints, how to obtain the optimal smoothing effects with the small cost is a key challenge. For this purpose, wavelet packet decomposition is modified by constructing cost function and ideal power trajectory sequences to obtain a new adaptive power distribution method for the CH-PV-PS generation system considering the boundary conditions of the system in this paper. At the same time, to meet the real-time control requirements of actual systems, an additive function is presented to improve the optimization speed of the adaptive power distribution method. In the meantime, a fuzzy controller is designed to optimize the inevitable delay time of the power scheduling system, and the starting threshold is set to avoid the frequently mode conversion of pumped storage. Finally, the performance of the method is evaluated based on the PV station data in Xiaojin County, Sichuan Province, China. Simulation results based on Matlab-simulink indicate that the proposed method can effectively suppress PV power fluctuations and ensure normal operation of the CH-PV-PS generation system within the multiple constraints. [ABSTRACT FROM AUTHOR]