Study On The Influence Of Time And Space Distribution Of Meteorological Parameters On Grid Operation Status

In power system analysis,we usually apply a single segment lumped parameter model to overhead transmission lines.In this model,it is assumed that the current density along the transmission line and material properties are uniform,and the change of conductor temperature caused by the time and space variation of meteorological parameters along the line is ignored.When transmission line parameters such as resistance,reactance,and admittance are calculated,the conductor temperature is supposed to be 20 ?.However,in reality,meteorological parameters along the line have significant time and space variation characteristics,resulting in conductor temperatures often varying by 200 C.Overhead transmission lines are the main component of power grids,and the variations of conductor temperature will also have an impact on the operation state of the power system.Firstly,according to the heat balance equation of CIGRE standard,the method of calculating conductor temperature based on actual meteorological data such as wind speed and ambient temperature is given.On this basis,the time and space distribution of meteorological data and conductor temperature of a 220kV overhead line in Shandong and a 500kV line in Northeast China are analyzed.Based on the relationship between conductor temperature and line parameters,the system power flow model considering the time and space distribution of meteorological data and the decomposition coordination solution are established.Through the analysis and comparison of power flow and maximum transmission capability of 5-bus system under four cases,it is verified that the time and space distribution of meteorological parameters has a great influence on the operating state of the system.Secondly,considering the time distribution characteristics of meteorological parameters,the seasonal time scale is applied to analyze the line current and system transmission capacity.Furthermore,an uncertainty analysis model is proposed to deal with the uncertain seasonal meteorological parameters and calculate the seasonal value of the line.The uncertainty analysis model consists of three parts:establishment of probability distribution models,Monte Carlo simulation,and operation risk assessment.The importance of seasonal thermal rating in improving transmission capacity of power system is verified by the analysis of seasonal thermal ratings of a 220kV overhead line in Shandong and transmission capacity of the 4-bus system.Finally,considering the space distribution characteristics of meteorological parameters,a line segmentation model based on wind speed variation along the line is proposed.The segmentation model is based on meteorological measurement points along the line.By setting a reasonable wind speed threshold,the line is divided into multi-segment lumped parameter models,which effectively solves the non-uniform distribution characteristics of line parameters.Through 4-bus system simulation,comparing the segmentation model with the traditional average model and the weighted average model,it is.verified that the segmentation model can more accurately analyze the operation status of transmission lines,which is of great significance to improve the transmission capacity.