With the comprehensive progression of China's electric power reform, the participation of hydropower in the spot market has become inevitable. For hydropower-dominated power grids, the tight hydraulic and electric coupling relationship between cascade hydropower plants and the policy requirement of clean energy consumption greatly increase the challenge of optimal scheduling. Based on the market characteristics and actual demand of the hydropower-dominated power grids, this paper discusses the day-ahead spot market trading mechanism to promote the guaranteed consumption of renewable energy. On this basis, a day-ahead optimal scheduling model is established which aims to minimize the comprehensive power purchase cost of the power system. The nonlinear factors in the scheduling model, such as the relationship between the water level and storage capacity of hydropower plants, the relationship between the water level and water consumption rate, and the constraints on the start-up and shutdown durations of thermal power units, are linearized through multiple linearization techniques. The original nonlinear model is transformed into a mixed integer linear programming (MILP) model and is then solved using a CPLEX solver. The developed model is verified by taking 10 thermal power plants and 22 hydropower plants in Yunnan Power Grid as a case study. The calculation time is 183.6s, the comprehensive power purchase cost of the system is 155.35·million CNY, and no abandoned water is generated in the three basins. The simulation results show that the proposed model has high solution accuracy and efficiency, and maximizes the hydropower consumption under the premise of meeting the minimum comprehensive power purchase cost. The findings of this study can provide a scientific basis for the development of the day-ahead spot market of hydropower-dominated power grids.
水资源承载力是实现"空间均衡"的重要刚性约束条件,其科学评价对于地区生态文明建设与可持续发展具有重要理论与实践意义.以往研究多集中于确定性评价,然而受多种因素的影响,水资源承载力评价也存在一定的不确定性.以新疆地区为例,采用Bootstrap、均匀分布假设法的随机抽样以及随机误差生成等方法,借助隶属度及不确定度的概念,量化指标权重及指标数据不确定性对研究区水资源承载力评价结果的影响.结果表明:基于Bootstrap和均匀分布假设法,由指标权重不确定性导致的新疆地区水资源承载力评价等级不确定度分别为21％和17％,由数据不确定性导致的不确定度为8％;随着指标权重和数据不确定性的增加,研究区水资源承载力评价等级的不确定度均随之增加;通过增加等幅误差的方法表明,数据不确定性对研究区水资源承载力评价等级的影响更大.研究成果可为科学评价水资源承载力、降低其不确性提供参考.
坝料密实度控制是土石坝心墙填筑质量控制的关键性指标,当前中国西南地区高坝心墙料普遍采用砾石土或掺粒土,传统坑测法测试密实度耗时耗力,而附加质量法目前主要用于堆石料密实度检测,对于心墙料还较少应用.基于附加质量理论模型,提出了一种新的数字量板构建方法.首先基于堆石体上每个测点的测试参数,通过公式计算建立密实度和测试参数的对等关系,得到理论量板;然后通过构建参数对等图制作了两种不同的量板.通过对砾石土心墙坝料密实度进行计算并和坑测法结果对比,验证了此方法的有效性.新的方法计算简便,参数对等灵活,与之前的数字量板相比,具有量板容易扩展、测试范围更广等优点.
在这个信息化、数字化飞速发展的时代,新媒体已经深深地渗透到大学生活中,对大学生的思想观念、价值观念产生着深远的影响. 《新时代大学生思想政治教育理论与实践研究》一书,以全面、深入的视角探讨了大学生思想政治教育在新媒体时代的诸多机遇与挑战,并系统地探讨了大学生思想政治教育的理论和实践问题.
现有的流域划分方法适用于高差清晰的地区,在平原河网地区适用性较差.为解决平原河网地区流域划分问题,根据平原河网地区的地形地貌特征,提出了一种综合各数据优势的多尺度、分层次的平原河网地区流域划分方法.该方法参考水系、道路、圩堤、闸泵和土地利用类型,结合单元格级网格和网格中心点空间分析数据,生成流域划分参考图.通过建立常州市钟楼区平原河网HSPF水文模型,对提出的平原河网地区流域划分方法进行了模拟应用.结果表明:钟楼区2020～2021 年水文过程模拟结果较好,德胜河桥、钟楼大桥和连江桥下站点的相关系数、纳什系数均大于0.75,满足模型模拟精度,提出的平原河网地区流域划分方法有一定的合理性和可行性.
