金沙江下游至三峡-葛洲坝梯级水库群发电联合调度增益机制分析

Study on the gain mechanism of joint power-generation operation of cascade reservoirs system between downstream Jinsha River and Three Gorges-Gezhou Dam

金沙江下游溪洛渡、向家坝至三峡、葛洲坝四库梯级为长江流域水能资源调控重点枢纽工程,开展四库发电联合优化调度效益显著。研究建立四库系统独立发电、联合两种模式下优化调度模型,采用长系列径流系列计算发电效益增益,统计增益的时间、年型、空间分布特征。提出基于全微分法的增益占比析因方法辨识发电增益受发电水量、水头影响贡献占比,归纳增益产生机制。结果表明:(1)消落期发电增益集中产生在5月份;向家坝、葛洲坝为主要受益水库。(2)联合增益的产生原因在于联合调度过程中溪洛渡、三峡均化了5月、6月放水过程,降低向家坝、葛洲坝的弃水量,抬升两库水头,增加发电效益。(3)向家坝的补偿增益受发电水量、水头贡献占比相当,葛洲坝的补偿增益主要以发电水头抬升的水头效益为主,溪洛渡、三峡的效益变化主要受联合调度过程中水头变化影响。

Located at the lower reaches of Jinsha River and middle reaches of Yangtze River,the cascade reservoirs system of Xiluodu,Xiangjia Dam,Three Gorges,and Gezhou Dam is an important hydrologic project in the Yangtze river basin.Joint operation of the reservoirs system has significant benefits.In this study,we established two optimized operation models for independent and joint power generation of the reservoirs system.Long inflow time series were used to calculate the gain of power generation benefit and to analyze the distribution of the gain in time,year type,and space.Moreover,we quantified the contribution percentages of released water and water head to the gain using the total differential equation.The results showed that:(1)the gain during the drawdown season mainly occurred in May,and was mostly in Gezhou Dam and Xiangjia Dam.(2)The gain was generated because Xiluodu and Three Gorges evened the water release process in May and June and reduced the discarded water volume of Xiangjia Dam and Gezhou Dam,thus increasing the water head of these two reservoirs.(3)The released water and water head contributed nearly equally to the gain generated in Xiangjia Dam.The main contribution factor to the gain in Gezhou Dam was water head.The variation of the gain generated in Xiluodu and Three Gorges was mainly influenced by the variation of water head during the joint operation.