Research Of Overhead Line Load Ability Based On Environmental Parameter Estimation

Nowadays the consumption of social power keeps increasing with the rapid development of society economy.The overhead line is an important part of power system.The capacity of overhead line is limited due to the restriction of the regulation about overhead line.Although setting up new overhead lines could improve the transmission and distribution of electric power system capacity,the cost of overhead line construction is huge and the construction cycle takes long time.How to make full use of existing transmission elements' transmission capacity has been one matter the power sector concerns most.Firstly,the main environment parameters affecting the overhead line carrying capacity such as temperature,wind speed and wind direction can be measured by the environmental measuring device,considering the environmental parameters and the spatial distribution characteristics of overhead lines,as well as the limited nature of environmental measurement devices,this paper starts with the research of environment parameters along the overhead line,according to the inverse distance weighted interpolation and ordinary kriging interpolation method,realizing estimation of environment parameters along overhead line without environment parameters measurement devices.Realizing distribution thermal rating of overhead line thermal load ability,not only reducing the investment costs,but also increasing the accuracy of overhead line current rating,which has certain theoretical and practical value.Secondly,this thesis researches the calculation of thermal load ability,including static thermal rating and dynamic thermal rating of overhead line.The environmental parameters which are obtained by interpolation method will be applied to solving the dynamic thermal rating of overhead line.Since the environmental parameters obtained have some uncertainty,this paper researches the uncertainty of environmental parameters based on Monte Carlo method.According to the heat balance equation of overhead line to analyze the uncertainty of current based of IEEE standard and CIGRE standard.Exploring the environmental parameters which influence the dynamic thermal rating most and find that wind speed to be the most critical factor.Finally,since the temperature of overhead line have an impact on the impedance,the influence of overhead line temperature cannot be neglected especially for long-distance overhead line.This thesis will discuss the parameter model of overhead line,supposing the temperature of overhead line is infinitely close to environmental temperature.Based on the temperature distribution along overhead line to realize segmentation.Researching the segmentation method of overhead line,realizing thennal rating in segmentation of overhead line.Based on Shanxi power grid geographical wiring diagram,select the overhead line starts from Yuheng end to Xinyi with a distance of 386.7km and the voltage level is 750kV.This paper research the PV curve features of load in single machine-single load under different temperature conditions.Researching the influence of temperature distribution along the overhead line on the running state of system.This thesis realize environmental parameter estimation using space interpolation method,assess uncertainty through Monte Carlo method as well as achieve segmentation of overhead line based on temperature distribution,improving the transmission capacity of overhead line effectively,mining the transmission ability of power grid.