Research On Temporal-Spatial Characteristics And Complementarity Of Wind And Solar Energy In China With Wide Areas

The global energy revolution led by wind power and solar power has taken place due to the increasing global issues of climate change,global warming,fossil energy crisis and so on.Renewable energy will dominate the global energy supply,especially the power supply in the future.However,different from the traditional power generation method,wind and solar power are characterized by intense fluctuation and intermittency.As a result,the power system has to supply enough flexibility to ensure the safe and effective utilization of renewable energy with a high penetration level.Improving the understanding of the fluctuation and intermittency of renewable energy and taking full advantage of renewable energy complementarity can effectively mitigate the fluctuation and intermittency.As a result,the needs for flexibility are significantly reduced,which is of importance for large scale renewable energy integration in the future.In the paper,the spatial-temporal characteristics of wind and solar resources and the complementarity are comprehensively analyzed in Chian within wide areas.First,the quantitative evaluation methods of fluctuation and intermittency of wind power are studied.The turbulence intensity and variogram function are introduced to meansure the fluctation amplitude and rate of wind power,respectively.The wind power intermittency is researched from the perspective of the physical nature of wind.Then the wind power intermittency is defined based on turbulence intermittency and the actual demand of the power system.Meanwhile,the evaluation index is proposed to quantitatively measure the wind power intermittency.Secondly,the evaluation index system of the wind resource is composed of the potential,variability,and intermittency indexes.The spatial-temporal characteristics of wind resources in China with wide areas are analyzed to provide the quality assessment of wind resources.The spatial atlas of theoretical potential,variability,and intermittency of wind resources are offered.Meanwhile,the temporal variations of wind power,variability,and intermittency are assessed based on 12 typical regions.Except for Hami,the wind power in other regions is the largest in winter or spring and the smallest in summer.The offshore wind power within 24 hours in a day.However,the onshore wind power strongly fluctuates within 24 hours in a day.For example,the wind power during daytime is larger than nighttime in East Inner Mongolia and the Qinghai-Tibet Plateau.While the wind power during daytime is smaller than nighttime in West Inner Mongolia,Hami,and the northern Gansu.In most regions,the amplitude of the fluctuation of wind power is larger in summer.The fluctuation velocity and intermittency of wind power are stronger in spring.The variability and intermittency are usually stronger in the periods of 06:01-12:00 and18:01-24:00.It finds that there is an amplitude modulating effect between the small scale and large scale fluctuations of wind speed within 24 hours.The evaluation index system of the wind resource is extended to solar resources to assess the spatial-temporal characteristics of solar sources in China within wide areas.The detailed spatial atlas of theoretical potential,variability,and intermittency of solar energy are offered.In addition,the temporal variations of PV power,variability,and intermittency are assessed based on 10 typical regions.In all the regions,the PV power is the largest in May,June and July and the smallest in December or January.The amplitude of the fluctuation of PV power is the largest in winter and the smallest in summer.The fluctuation velocity is the largest in spring and the smallest in winter.The intermittency of PV power is stronger in spring and autumn and is weaker in winter and summer.The variability and intermittency are usually stronger in the periods of 06:01-10:00 and 16:01-20:00.While the fluctuation velocity and intermittency are weaker during the periods of sunrise,sunset and noon.The quantitative analysis shows that the fluctuation and intermittency of solar resources are relative definite.Finally,the complementarity of renewable energy is assessed in China with wide areas.The complementarity of renewable energy based on load demand is firstly defined.The evaluation indexes of complementarity are proposed based on Kendall rank correlation analysis.The impacts of spatial areas and time scales on the complementarity are analyzed.Meanwhile,different complementarity types are compared.Finally,the complementarity results between wind and solar resources are evaluated.The results show that the gap between renewable power generation and load demand can be effectively reduced.In addition,the standard devitation of power generation is effectively decreased and the power generation would be smoother by the complementarity effect.The peak-phase difference dereased to 2?6 h by the effect of PV power.The anti-peak regulation phenomena of wind power can be changed when the proportion of PV power is approximately 0.2?0.3.