混流式水轮机内特性模型改进及在外特性曲线拓展中的应用

发布时间：2018-03-12 10:33

本文选题：模型　切入点：计算机仿真　出处：《农业工程学报》2017年07期 　论文类型：期刊论文

【摘要】：混流式水轮机综合特性曲线反映了水轮机高效率区域的特性,但不满足水轮机大范围内过渡过程仿真需求,在仿真前需要对水轮机低效率及负效率区域的特性进行拓展。目前常用的拓展方法其原理均是根据水轮机综合特性曲线中各参数的变化趋势并结合飞逸特性曲线等约束进行的拓展,没能充分考虑水轮机内在规律,拓展结果过度依赖个人经验,具有较大的随意性。该文通过分析水轮机各部件的能量损失建立了水轮机能量平衡关系式,结合流量调节方程对水轮机内特性模型进行了改进。针对改进后的内特性模型特点设计了一种遗传算法与最小二乘法相结合的参数辨识方法,采用水轮机综合特性曲线及飞逸特性曲线对模型参数进行了辨识,采用辨识后的水轮机模型绘制了较大范围的水轮机特性曲线并与实测特性曲线进行了比对,并结合实测结果对误差来源及误差对过渡过程影响进行了分析。结果表明改进后的混流式水轮机内特性模型能够正确描述水轮机特性,采用最小二乘法与遗传算法相结合的方法能够辨识模型中的参数,将该模型应用在水轮机外特性曲线拓展及过渡过程仿真中,机组过渡过程中最大转速上升率相对误差从2.11%降低到0.54%,最大压力上升率相对误差从10.70%降低到9.52%,说明该模型能够减小仿真误差、减小传统方法中对个人经验的依赖,对过渡过程计算提供了参考。
[Abstract]:The comprehensive characteristic curve of Francis turbine reflects the characteristics of the high efficiency region of the turbine, but it does not meet the needs of the transient process simulation in a wide range of hydraulic turbines. It is necessary to extend the characteristics of the low efficiency and negative efficiency region of the turbine before simulation. At present, the principle of the expansion methods is based on the variation trend of the parameters in the comprehensive characteristic curve of the turbine and combined with the flight escape characteristic curve. The expansion of equal constraints, The inherent law of the turbine was not fully considered, and the expansion result was excessively dependent on personal experience, which was arbitrary. By analyzing the energy loss of the various components of the turbine, the energy balance relationship of the turbine was established in this paper. According to the characteristics of the improved internal characteristic model, a parameter identification method combining genetic algorithm and least square method is designed. The model parameters are identified by the comprehensive characteristic curve and the flight characteristic curve of the turbine, and a large range of characteristic curves of the turbine are drawn by using the identified model and compared with the measured characteristic curve. The results show that the improved internal characteristic model of Francis turbine can accurately describe the characteristics of the turbine. The parameters of the model can be identified by combining the least square method and genetic algorithm. The model is applied to the expansion of the outer characteristic curve of the turbine and the simulation of the transition process. The relative error of the maximum speed rise rate decreases from 2.11% to 0.54, the relative error of the maximum pressure rise rate decreases from 10.70% to 9.52, which shows that the model can reduce the simulation error and reduce the dependence on personal experience in the traditional methods. It provides a reference for the calculation of transition process.
【作者单位】：西安理工大学水利水电学院;
【基金】：国家自然科学基金资助项目(51479166);国家自然科学基金资助项目(51339005)
【分类号】：TK733.1

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