基于可解释机器学习的耗水率估算方法

    Water consumption rate prediction method based on interpretable machine learning

    • 摘要: 耗水率的精确估算直接关系到水电及梯级发电调度计划的准确性和可操作性,而针对水电站水头-耗水率曲线随着电站长期运行与实际结果发生严重偏差导致耗水率的准确估算极其困难的问题,本文提出了一种基于可解释机器学习数据驱动模型的耗水率估算方法。首先,采用Pearson相关性分析方法对历史水电长序列实际运行数据进行分析,挖掘运行数据中的时序特征,确定库水位、水头、发电流量等影响耗水率的影响因子;接着以挖掘的因子作为输入,以处理非线性关系为优势的支持向量回归方法(SVR)构建了耗水率预测模型;最后,引入SHAP可解释性算法计算各输入因子的贡献值,根据贡献值对预测模型进行迭代校正。以长江流域某水电站进行模拟仿真,实例结果表明该方法预测耗水率的RMSE和MAE分别为0.0619 m3/kWh和0.0412 m3/kWh,相较于传统插值法的0.21 m3/kWh和0.18 m3/kWh分别降低约40%和60%,NSE值为0.9724相较于传统插值法的0.75提升约20%,有效克服了运行条件变化导致的耗水率偏差问题,同时使模型结构和预测结果的可解释性更强。

       

      Abstract: The accurate estimation of water consumption rate is directly related to the accuracy and operability of hydropower and cascade power generation scheduling plans. In response to the serious deviation between the head water consumption rate curve of hydropower stations and the actual results due to long-term operation, which makes accurate estimation of water consumption rate extremely difficult, this paper proposes a water consumption rate estimation method based on an interpretable machine learning data-driven model. Firstly, the Pearson correlation analysis method is used to analyze the historical long-term operation data of hydropower plants, extracting time-series features from the operational data and determining influencing factors such as reservoir water level, head, and generation flow that affect the water consumption rate. Then, these extracted factors are used as inputs to construct a prediction model for the water consumption rate using Support Vector Regression (SVR), which is advantageous in handling nonlinear relationships. Finally, the SHAP interpretability algorithm is introduced to calculate the contribution of each input factor, and the prediction model is iteratively corrected based on the contribution values. The simulation was conducted on a hydropower station in the Yangtze River Basin. The results demonstrate that the proposed method achieves RMSE and MAE values of 0.0619 m³/kWh and 0.0412 m³/kWh, respectively, in predicting water consumption rate, representing reductions of approximately 40% and 60% compared to the traditional interpolation method (0.21 m³/kWh and 0.18 m³/kWh). Additionally, the Nash-Sutcliffe efficiency (NSE) coefficient reaches 0.9724, showing an improvement of about 20% over the traditional method (NSE = 0.75). The proposed approach effectively mitigates deviations in water consumption rate caused by variations in operational conditions while enhancing the interpretability of both the model structure and prediction results.

       

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