基于复杂约束归一化处理策略的梯级水电调峰方法

Peak Shaving Method of Cascade Hydropower Stations Based on Normalization Processing Strategy With Complex Constraints

随着我国水电的飞速发展,大规模梯级水电短期调度面临繁杂的水力电力约束,复杂约束的非凸、非线性特性使得水电短期优化异常困难,无法在可接受时间内获得满足精度要求的优化结果。提出了一种基于复杂约束归一化处理策略的梯级水电短期调峰调度方法。首先,深入分析约束特征,根据约束输入输出方式的不同,将约束分为5类,总结出各类约束对应的转化方法;接着,将这些约束采用发电流量进行统一转换,运用集合理论对同类约束进行合并,减少整体的约束数量,获得可行的约束边界;最后,采用线性化方法对模型目标函数及一元二元非线性函数进行线性化处理,构建出水电短期优化调度的混合整数线性规划模型(mixed integer linear programming,MILP),降低梯级调峰求解的难度。以我国西南某流域大型水电基地11座梯级水电站为例,进行了所提方法与非线性模型和未约束处理的MILP模型的对比分析。结果表明,线性化方法可以有效降低求解难度,能够缓解非线性模型难以求解大规模水电调度问题的窘况;在线性化的基础上进一步进行约束处理可以明显提高大规模梯级水电调峰调度的求解效率,汛期和枯期11库的求解时间分别减少了12450.28s和6980.87s,表明所提方法在大规模梯级水电调峰方面的实用性。

With the rapid development of the hydropower in China,the short-term scheduling of large-scale cascade hydropower is faced with complex hydraulic and power constraints.The non-convex and nonlinear characteristics of the complicated constraints make it extremely difficult to achieve the results of the short-term optimization that meet the accuracy requirements in an acceptable time.This paper presents a short-term peak shaving scheduling method of the cascade hydropower based on a normalization processing strategy of the complex constraints.First,the constraint characteristics are deeply analyzed.According to the different input and output data,the constraints are classified into five types,and the corresponding transformation methods are summarized.Then,these constraints are transformed by the power releases,and the same constraints are merged by using the set theory to reduce the number of constraints and obtain the feasible constraint boundary.Finally,the linearization method is used to linearize the model objective function and the one-dimensional and two-dimensional nonlinear functions.A mixed integer linear programming model(MILP)for the short-term peak shaving optimal dispatching of hydropower is constructed to reduce the difficulty of the cascade peak shaving solution.Taking the 11 cascade hydropower stations in a large hydropower base in Southwest China as an example,the comparative analysis of the proposed method with the nonlinear model and the MILP model without constraint processing strategy is carried out.The results show that the linearization method in this paper effectively reduces the difficulty in solving and alleviating the dilemma of large-scale hydropower dispatching.The constraint processing on the basis of the linearization method significantly improves the efficiency of peak shaving of the large-scale cascade hydropower.The solution time in the flood season and the dry season is reduced by 12450.28s and 6980.87s respectively,indicating the practicability of the proposed method in peak shaving operation of the large-scale cascade hydropower.