基于聚类EEMD-PCA-LSTM与误差补偿的光热电站短期太阳直接法向辐射预测

Prediction of Short-term Direct Normal Irradiance of Concentrated Solar Power Plant Based on Clustering EEMD-PCA-LSTM and Error Compensation

  • 摘要: 太阳直接法向辐射(Direct normal irradiance,DNI)的变化影响光热发电的可靠性和效率。以西北某光热电站为研究对象,提出一种聚类、集合经验模态分解(Ensemble empirical mode decomposition,EEMD)、主成分分析(Principal component analysis,PCA)和长短期记忆(Long short-term memory,LSTM)神经网络与误差补偿的光热电站短期DNI预测模型。首先,充分考虑影响DNI的环境因素,研究气象参数与DNI间的关系,利用近邻传播(Affinity propagation,AP)聚类算法得到同一天气下的典型日,利用EEMD将原始DNI序列进行分解得到各子模态,降低序列的非平稳性;其次,利用PCA得到关键影响因子,使原始序列相关性和冗余性降低,减少模型输入维度;然后,利用LSTM网络对各分解子模态建模预测得到初始预测DNI序列,将其与真实序列作差,得到两者间的误差序列,重新建立LSTM网络对误差序列进行预测,即误差补偿;最后,将初始预测DNI与误差序列求和,得到最终的预测模型,实现对光热电站短期DNI的预测。预测结果表明,该预测模型效果较好,预测精度达94%。

     

    Abstract: The variation of direct normal irradiance(DNI) affects the reliability and efficiency of concentrated solar power generation. A short-term DNI prediction model of a photovoltaic thermal power station in northwest China is proposed based on clustering, ensemble empirical mode decomposition(EEMD), principal component analysis(PCA), long short-term memory(LSTM) neural network and error compensation. The environmental factors that affect DNI are considered fully. Firstly, the relationship between meteorological parameters and DNI is studied. The typical days in the same weather are obtained by using the affinity propagation(AP) clustering algorithm. The each sub-mode is obtained by using EEMD to decompose the original DNI sequence, reducing the non-stationary of the sequence. Then PCA is used to get the key influencing factors, which reduces the correlation and redundancy of the original sequence and reduces the model input dimension. Secondly, the LSTM network is used to model and predict each decomposed sub-model to obtain the initial predicted DNI sequence, and the error sequence between them is obtained by making a difference between the LSTM network and the real sequence. The LSTM network is reestablished to predict the error sequence, that is, error compensation. Finally, the initial predicted DNI and the error sequence are summed to obtain the final prediction model, and the short-term DNI of the optical thermal power station is predicted. The prediction results show that the prediction model is effective and the prediction accuracy is 94%.

     

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