面向风电场运行的WRF短期风速分段混合订正方法

Segmented error-aware hybrid correction for WRF wind speed forecasts

  • 摘要: 在全球气候变化加剧和能源结构加速转型背景下,风电作为清洁低碳能源在新型电力系统中发挥着重要作用. 风速是影响风电功率预测的关键气象要素,提高风速预测精度对于提升风电场运行效率具有重要意义. 然而,由于风速具有较强的随机性和不稳定性,其精准预测仍面临较大挑战. 本文以甘肃某风电场为研究对象,基于天气研究与预报(WRF)数值天气预报模式开展短期风速预测研究. 在分风速段框架下,引入概率密度匹配(PDF)、门控循环单元(GRU)和K近邻(KNN)三种方法,构建基于误差感知的分段混合订正模型(Segmented error-aware hybrid correction,SEHC),对WRF预报风速进行订正. 结果表明,相比原始WRF预报,SEHC方法可使平均绝对误差(MAE)降低约80%,箱线分布离散度和尾部分位明显收敛. 其中,在3,10 m s−1风速区间内预测精度提升最为显著,并能有效降低高风速条件下的极端偏差. 研究结果表明,SEHC方法能够显著提升风速预测精度,可为风电场精细化风速预测及电网调度提供参考.

     

    Abstract: In the context of intensified global climate change and the accelerating transition of energy systems, wind power—as a clean and low-carbon renewable energy source—has become an important component of modern power systems. Accurate wind speed forecasting is vital for predicting wind power, grid dispatching, and stably operating wind farms. Therefore, improving the accuracy of wind speed predictions is crucial for enhancing the efficiency of wind energy utilization and supporting the safe integration of large-scale wind power into the power grid. However, because of the inherent intermittency, randomness, and nonlinearity of wind speed, achieving accurate and stable forecasts remains challenging. Numerical weather prediction (NWP) models, such as the Weather Research and Forecasting (WRF) model, are widely used for wind speed forecasting. However, their predictions typically contain systematic biases and structural errors caused by imperfect initial conditions, physical parameterization schemes, and complex terrain effects. In this study, a wind farm located in Gansu Province, China, is selected as the research object. Based on the WRF NWP model, short-term wind speed forecasts are conducted, and a segmented hybrid correction framework is proposed to improve the prediction accuracy. Specifically, a Segmented Error-aware Hybrid Correction (SEHC) framework is developed to correct the wind speed predictions by the WRF model using a wind-speed-segmented structure. Within this framework, three complementary correction methods—probability density function (PDF) matching, gated recurrent unit (GRU), and the k-nearest neighbors (KNN) algorithm—are integrated to capture different types of prediction errors. While PDF matching is used to reduce systematic distribution bias, the GRU model is employed to capture temporal dependencies in wind speed sequences, and the KNN algorithm is utilized to address local nonlinear relationships in the data. By combining these methods within different wind speed segments based on the dominant error characteristics, the proposed SEHC framework aims to achieve a more robust and accurate wind speed correction. The model was trained and evaluated using observational wind speed data and WRF forecast data with a temporal resolution of 15 min. The dataset encompassed a full year of observations from the selected wind farm. The performance of the proposed correction framework was evaluated using several statistical indicators, including mean absolute error (MAE), root mean square error (RMSE), correlation coefficient, and distribution-based metrics. The results showed that the proposed SEHC framework significantly improved the accuracy of wind speed predictions compared with the original WRF model outputs. In particular, the MAE was reduced by approximately 80%. In addition, the dispersion of the boxplot distribution and the tail quantiles of prediction errors were reduced significantly after correction. The most significant improvement was observed in the wind speed range of 3–10 m·s−1, which corresponded to the region where the power output of the wind turbine increased rapidly along the power curve. Furthermore, the proposed method effectively suppressed extreme prediction deviations under high-wind conditions and thereby reduced the potential risks associated with large forecast errors. In general, the proposed SEHC framework demonstrated a strong capability for improving the accuracy of wind speed predictions without modifying the physical structure of the NWP model. The framework provides a practical and computationally efficient solution for wind speed post-processing in wind farm applications. The results of this study provide useful technical support for refined wind speed forecasting and offer valuable references for predicting wind power, grid dispatching, and the operational management of wind farms.

     

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