Recently

with the growing PV capacity

analyzing its impacts on reliability of power grid accurately has practical significance.This paper puts forward a novel method for modeling the PV output

based on optimal segmentation and multidimensional clustering method

which can retention circadian and seasonal timing characteristics well.Firstly

according to the effective output time of PV in a day

using Fisher optimal segmentation algorithm

year simulation period gets optimal segmentation.Secondly

using multidimensional cluster method of fuzzy c-mean cluster algorithm

each period is analyzed.This method makes photovoltaic output modeling more refined

and preserves its local properties better.Applied in IEEE-RTS test system

the reliability analysis uses meas-ured PV output in Ningxia.The year simulation period is divided into five optimal periods

and at each period

the impact on power system reliability of PV is analyzed.The result shows the effectiveness of the method

and provides significant guidance on PV capacity planning.