水库汛末蓄水防洪与兴利合作关系建模分析

A Model Analysis of Cooperative Relationship between Flood Control and Water Conservation in Reservoir Pre-impoundment

水库汛末提前蓄水调度具有主从递阶的决策结构,而发电目标的异参同效性使给定防洪规则时最优蓄水方案不唯一,即水库优化调度求解存在“不适定性”,水库运行管理单位是否选择对防洪安全更有利的蓄水方案影响调度效益的实现,表明防洪与兴利在竞争关系外还存在合作潜力。针对这一问题,围绕如何加强兴利部门对防汛部门的合作意愿从而提升水库调度整体效益,建立了基于下层决策者满意度的合作激励模型。该模型以不适定二层规划为框架,从水库调度决策特点出发,对兴利部门的合作意愿与其在给定防洪规则下的预期发电收益的非线性相关关系进行描述,进而得到兴利部门选择有利于防洪目标蓄水方案的概率,并采用多种群混合进化粒子群算法对模型求解。同时设置量化指标,对合作激励机制下的水库优化调度决策效率损失和整体目标实现度进行评估。在三峡水库汛末提前蓄水调度实例中,将新模型与乐观、悲观和部分合作模型结果进行了对比分析。结果表明,合作激励的机制会促使防汛部门适当让渡部分效益以提高水库蓄水发电效益,进而鼓励兴利部门选择更有利于防洪安全的方案,同时能较为显著地减少主从竞争博弈导致的调度决策效率损失。此外,与线性满意度模型相比,本文提出的非线性的满意度~预期调度效益值关系曲线更符合水库调度的实际决策特征。

Within the hierarchical decision structure of reservoir pre-impoundment operations,the parameter equifinality of hydropower gen⁃eration leads to non-uniqueness of optimal solutions,i.e.,the“ill-posedness”of solving reservoir operation optimization problems.Under such circumstances,the realization of operation benefits is affected by whether the reservoir operator selects the refill plan in favor of flood safety,implying that not only competitive relationship but also cooperative potential exists between flood control and water conservation.In light of this,a cooperation incentive(CI)model based on the lower-level satisfaction is developed to provide a mechanism to promote the wa⁃ter conservation department’s cooperation with the flood control department and enhance the reservoir operation benefit.Based on the frame⁃work of ill-posed bilevel programming,regarding the actual decision characteristics,the model described the nonlinear correlation between the cooperation willingness and the expected benefit of the water conservation department given certain flood control rule,so that the proba⁃bility of selecting the refill plan in favor of flood safety can be derived.The CI model is solved by using multi-swarm evolutionary particle swarm optimization algorithms.Quantitative indicators are proposed to evaluate the Pareto efficiency loss and overall goal achievement of the reservoir operation optimization under cooperation.In the Three Gorges Reservoir pre-impoundment case study,the results are compared with those of the optimistic,pessimistic,and partial cooperation models.Results show that the CI mechanism motivates the benefit conces⁃sion of the flood control department to increase hydropower generation and encourage the water conservation department’s choice in favor of flood safety.Further,the efficiency loss in operation decisions due to competitive gaming process can be more prominently reduced.Findings also indicate that nonlinear satisfaction-expected benefit relationship can better describe the practical decision making in reservoir operation.