基于Transformer模型的级联系统压强预测研究

Pressure Prediction of Cascade System Based on Transformer Model

  • 摘要: 针对离心级联系统缺乏预测压强的手段而导致运行人员难以及时准确预知压强变化的问题,采用改进Transformer模型,以实现级联系统压强的有效预测。通过二维卷积层捕捉输入序列特征关系,并采用一维卷积使相邻时间步的信息融合。为降低计算复杂度、提高模型计算效率,利用多头稀疏自注意力机制对注意力权重矩阵进行稀疏化处理。在解码端采用自回归式解码,提高生成序列的准确性。通过模拟贫料干管电动调节阀误动作引起的压强变化,验证了模型在60 s内的压强预测效果。改进Transformer模型对压强预测的平均绝对误差、平均绝对误差百分比和均方根误差分别为0.42、1.5%和0.48,相比传统Transformer模型,分别降低了59.6%、57.1%和61.9%,且与其他预测模型相比,预测精度也更高。

     

    Abstract: Disturbances in centrifugal cascade systems manifest as flow or pressure perturbations, typically exhibiting abnormal pressure fluctuations. Taking staged centrifugal cascades as an example, dynamic hydraulic analysis reveals that disturbances propagating toward the depleted-end units cause pressure oscillations that amplify progressively downstream. During operational transitions, dedicated personnel must be arranged for real-time monitoring and necessary intervention to maintain the feed main pressure of Unit 01 within its safe operating range. Accurate determination of pressure trends in Unit 01’s feed main requires both prolonged disturbance propagation durations and operators’ extensive experience. Conventional monitoring approaches predominantly rely on threshold-triggered alarms control systems and operator experience-driven judgments. These methods cannot promptly capture subtle pressure variations during disturbances’ incipient stages, while the nonlinear, multivariable-coupled nature of cascade systems creates intricate parameter interdependencies. Consequently, operators face difficulties in timely disturbance detection, predicting propagation patterns, and assessing impact scopes. Due to the lack of means to predict pressures in a centrifugal cascade system, it is difficult for operators to predict pressure changes instantly and accurately. This limitation hinders timely response to potential disturbances impacting system stability and safety. To address this challenge, an improved Transformer model specifically designed for effective pressure prediction in centrifugal cascade systems was proposed. The characteristic relation of the input sequence was captured by a two-dimensional convolution layer, and the information at the adjacent time steps was amalgamated by a one-dimensional convolution layer. Crucially, to overcome the computational inefficiency of the standard Transformer, especially for long sequences common in pressure monitoring, a mechanism of multi-head sparse self-attention (MHSSA) was employed. This MHSSA mechanism sparsifies the attention weight matrix to significantly reduce the computational complexity and improve the computational efficiency. Furthermore, to enhance the temporal coherence and accuracy of the generated pressure sequences, autoregressive decoding was adopted. By simulating the pressure change caused by mis-operation of an electric regulating valve on the main pipe for the depleted material, the pressure prediction effect of the model within 60 s was verified. The average absolute error (MAE), the mean absolute percentage error (MAPE) and the root-mean-square error (RMSE) of the improved Transformer model for pressure prediction are 0.42, 1.5% and 0.48, respectively. Compared with the traditional Transformer model, these metrics are reduced by 59.6%, 57.1% and 61.9%, demonstrating the effectiveness of the proposed improvements. Furthermore, the proposed model (F4) exhibits superior prediction accuracy compared to other baseline models, including a standard LSTM (F1), an encoder-decoder LSTM (F2), and the traditional Transformer (F3), across all evaluation metrics. The significant performance gains highlight the model’s capability in capturing complex spatio-temporal dependencies in cascade system pressure dynamics, providing a valuable tool for real-time monitoring and early anomaly detection.

     

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