有云条件下太阳辐射短临预报订正技术研究

Correction technology of short-time solar radiation forecast based on cloud cover

利用2019年甘肃省7个光伏电站太阳总辐射、气温、相对湿度等观测数据和WRF模式太阳总辐射预报产品及FY静止卫星总云量数据,在大气透过率与气象要素相关性分析及数值模式预报能力评估基础上,对甘肃太阳总辐射短临预报误差进行订正研究。结果表明:大气透过率与气温呈显著正相关(相关系数为0.61),而与相对湿度、气压、总云量呈显著负相关(相关系数依次为-0.44、-0.31、-0.81),总云量对太阳辐射的衰减作用贡献最大,其次为相对湿度。太阳辐射预报偏差较大,误差呈明显的"单峰型"月际分布,6月最大,均方根误差在冬季最小为45.63 W·m^(-2),夏季最大为240.4 W·m^(-2);预报能力在晴天强、云天较差,其误差主要来源于位相偏差和系统偏差。考虑云量的太阳辐射短临预报订正效果显著,阴天太阳辐射预报订正后的均方根误差降幅为101~216.4 W·m^(-2),平均绝对误差降幅为59.5~173.07 W·m^(-2);误差最大的夏季,太阳辐射预报订正后的均方根误差降幅为1.92~64.23 W·m^(-2)。

Based on observed total solar radiation,air temperature,relative humidity and air pressure data at representative photovoltaic power stations of Gansu Province,total solar radiation data forecasted by WRF model,and total cloud cover products from FY satellite in 2019,the correlation between total solar radiation and meteorological factors was analyzed,and the prediction ability of WRF model was evaluated,firstly.And on this basis the errors of short-time solar radiation forecast were corrected.The results show that the atmospheric transmissivity was positively correlated with air temperature,and the correlation coefficient was 0.61,while it was negatively correlated with relative humidity,air pressure and total cloud cover,and the correlation coefficients were-0.44,-0.31 and-0.81 in turn.The contribution of total cloud cover to solar radiation attenuation was the most,followed by relative humidity.The deviation of solar radiation forecasted by WRF model was bigger,and the monthly distribution of forecast errors appeared‘single peak’pattern,the forecast errors was the biggest in June.The root mean square error(RMSE)of solar radiation forecast was the smallest in winter(45.63 W·m^(-2))and the biggest in summer(240.4 W·m^(-2)).The forecast ability of WRF model was better on sunny days or partly cloudy days,while it was worse on cloudy days.The forecast errors mainly came from phase bias and system bias.The correction effect of solar radiation forecast considering cloud cover was significant,the RMSE of solar radiation forecast after correction sharply decreased by 101-216.4 W·m^(-2) on cloudy days,the average absolute error decreased by 59.5-173.07 W·m^(-2),and the RMSE decreased by 1.92-64.23 W·m^(-2) in summer with the maximum error.