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Impact of Tropical Convective conditions on Solar Irradiance Forecasting based on Cloud Motion Vectors

Roy, Arindam and Hammer, Annette and Heinemann, Detlev (2021) Impact of Tropical Convective conditions on Solar Irradiance Forecasting based on Cloud Motion Vectors. In: IEA Task 16. DACH2022 Meteorologietagung, 21.-25. Mar. 2022, Leipzig, Deutschland.

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Abstract

Cloud Motion Vector (CMV) estimation from consecutive images is widely used commercially for providing hours-ahead intraday forecasts of solar irradiance and PV power production. The modelling assumptions in these methods are generally satisfied for advective motion, common in mid-latitudes, but strained for tropical meteorological conditions dominated by convective clouds. The region under analysis in this study encompasses both tropical and sub-tropical climatic zones and is affected by seasonal strong convection, i.e., the South Asian Monsoon. The purpose of this study is to benchmark the monthly forecast error of three commonly used motion estimation techniques - Block-match, Farnebäck and TV-L1, for analysing their performance on a seasonal basis. Especially the analysis of the limitations of image processing based Block-match and Optical flow techniques in predicting irradiance during the Monsoon period with frequent convective formation and dissipation is the main focus of this work. Forecasted Cloud Index (CI) maps are validated against reference analysis CI maps for the period 2018-2019 at forecast lead times of 0 to 5.5 hours ahead using the Peak Signal to Noise Ratio (PSNR) metric for estimation of accuracy. Persistence of analysis cloud index maps are used as the reference worst case scenario forecast. Site-level forecasts of irradiance for the same period are validated against ground measured irradiance from two BSRN stations - Gurgaon and Tiruvallur, located in Northern and Southern India respectively. Summer Monsoon pattern of forecast error dominates at the image-wide level and a marked reduction of the 30 minutes ahead forecast accuracy by 3 dB in terms of Peak Singal to Noise Ratio (PSNR) from March to August, can be observed for all the three methods and the worst case persistence scenario. Both the optical flow methods outperform Block-match by 0.5 dB for the entire period of analysis. The Gurgaon BSRN site is affected by Summer Monsoon and shows an increase in nRMSE by a factor of 3 for all the methods from March to August, with the seasonal pattern of forecast error closely matching the image-wide forecast accuracy. The forecast error for the Tiruvallur BSRN station on the other hand reaches its peak in December (Data for October and November are absent), due to its location in the Winter Monsoon climatic zone. Again, the nRMSE for all methods increase by a factor of almost 3 from March to December. The inter-method difference in accuracy is not significant and the seasonal difference (20% nRMSE) dominates.

Item URL in elib:https://elib.dlr.de/146159/
Document Type:Conference or Workshop Item (Speech)
Title:Impact of Tropical Convective conditions on Solar Irradiance Forecasting based on Cloud Motion Vectors
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Roy, ArindamArindam.Roy (at) dlr.deUNSPECIFIED
Hammer, AnnetteAnnette.Hammer (at) dlr.dehttps://orcid.org/0000-0002-5630-3620
Heinemann, Detlevdetlev.heinemann (at) uni-oldenburg.deUNSPECIFIED
Date:19 November 2021
Journal or Publication Title:IEA Task 16
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Accepted
Keywords:Cloud Motion Vector, Solar Irradiance, Intra-day Forecast, Convection
Event Title:DACH2022 Meteorologietagung
Event Location:Leipzig, Deutschland
Event Type:international Conference
Event Dates:21.-25. Mar. 2022
Organizer:DMG, ÖGM, SGM
HGF - Research field:Energy
HGF - Program:Energy System Design
HGF - Program Themes:Energy System Transformation
DLR - Research area:Energy
DLR - Program:E SY - Energy System Technology and Analysis
DLR - Research theme (Project):E - Systems Analysis and Technology Assessment
Location: Oldenburg
Institutes and Institutions:Institute of Networked Energy Systems > Energy Systems Analysis, OL
Deposited By: Roy, Arindam
Deposited On:15 Dec 2021 18:20
Last Modified:15 Dec 2021 18:20

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