Search

The tournament operator genetic algorithm (TGA) often shows poor convergence and easily gets trapped in a local optimum when solving optimized reservoir scheduling problems. The selection operation is the most important operation determining an algorithm's convergence; therefore, this study proposes a proportional reproduction selection-based operator genetic algorithm (RGA) and a steady-state reproduction selection-based operator genetic algorithm (SGA) as alternatives to TGA. This study used TGA, RGA, and SGA to solve the maximum power generation model for the Gezhouba hydropower station, the largest runoff hydropower station in the world. Then, by using the maximum hydropower station output under a given typical runoff scenario as the optimization criterion, this study evaluated the optimized solution performance of the GA using different selection operators. The results show that TGA, SGA, and RGA can be applied to solve the short-term reservoir scheduling model. As the number of iterations increases, the hydropower station output optimized by these three GAs increases. Based on the maximum power generated by the Gezhouba hydropower station, SGA and RGA provide better results than TGA, and between SGA and RGA, the former provides better results. [ABSTRACT FROM AUTHOR]

This study proposes and tests a new approach to detect and analyze changes in flood regime using a distributed hydrological model (EasyDHM), using the Second Songhua River basin, China, as a case study. Model calibration and parameter sensitivity were used to represent flood regimes in a 60-year series (1954-2013), with three different flood regime periods identified. The changes in flood regime were estimated by model parameters, flood result residuals and the overall process in the hydrological model in the three periods. The results show that human activities significantly impacted flood regimes, with significant flood regime change largely attributed to increases in water storage in multiple small reservoirs. Flood volume was reduced significantly between the periods in all three watersheds. The parameters also changed in variety between the periods. The study highlights the importance of incorporating data on small-reservoir constructions in flood control systems. [ABSTRACT FROM AUTHOR]

The joint operation of cascaded reservoirs can generate various compensation benefits. How to calculate all compensation benefits scientifically and fairly, and how to share these benefits reasonably, will be of great importance for the sustainable development of the basin and for the rolling development of a cascaded reservoir of a hydropower station. This article examines the joint operation of Longyangxia and Liujiaxia reservoirs at the upper reaches of the Yellow River in China. To study the reservoir compensation benefits, the authors have built a compensative regulation model for the joint operation of the reservoir group. The electricity generation compensation economic effects of the joint operation of the Longyangxia and Liujiaxia reservoirs in 2005 were calculated. The results showed that the joint operation of cascaded reservoirs can generate remarkable economic benefits. [ABSTRACT FROM AUTHOR]

The completion of Shuibuya, the last hydropower station to be constructed in the Qingjiang cascade, signifies China's successful development of the world's largest mixed cascade hydropower generation system. Joint operation of such cascaded hydropower stations is considered necessary to improve hydropower output in China. In this study, two modeling methods – routine and optimal operations – were adopted, based on existing rules of reservoir operation, to determine the effects of joint operation. To investigate the realistic and potential effects, the two models were computed using observed runoff data (1951–2009). The potential effects were identified by comparing the total hydropower generation two single cascades and their cogeneration. Under the routine operational mode, the incremental power generation of joint operation would be 5.73 × 10 8 kWh, an increase of 5‰ compared to isolated operation. However, even in isolation, if reservoir operation is optimized through the dynamic programming algorithm, the incremental power generation of the cascade would be 42.24 × 10 8 kWh, which is seven times that of joint operation with routine reservoir operation (5.73 × 10 8 kWh). The results showed that, under current reservoir operating rules, there is little room for improvement in hydropower generation, although joint operation could increase hydropower generation to a certain extent, especially in the reservoirs' refill and release stages. China must amend its existing operational mode for reservoirs to enhance the economic benefits of cascade hydropower stations. Furthermore, to meet increasing demands for both water and energy, carefully considered planning of constructing clusters of these stations is required. [ABSTRACT FROM AUTHOR]