Key Technology Research On Transmission Line Ice Monitoring By Optical Fiber Type In Smart Grid

Intelligent power grid has become the development trend of power system,and it put forward higher requirements for safety monitoring aspect of transmission lines.Among them,accurate and real-time monitoring of transmission line ice thickness is a part of important contents.Transmission line icing will affect the safe operation of the power system.Heavy icing may cause serious damage to the power transmission line,tower,etc.,and even break the cable.If the above situations happened,generally they will give rise to serious property damage.Fiber Bragg grating(FBG)sensing technology with its unique advantages is widely used in many fields.Currently,it will become an important part of smart grid by combining fiber grating technology with power grid.This paper focuses on technology research of transmission line icing monitoring by optical fiber in smart grid.The main research works and achieved results are listed below.1.In order to achieve accurate axial strain of transmission line,I designed a new type of fiber grating strain monitoring device,which includes two parts,fiber grating strain sensors and strain synchronous induction similar cantilever structure.Firstly,the similar cantilever is modeled for its mechanical properties to analyze its feasibility.Secondly,material selection and size design about the structure were analyzed.In the choice of material,the final choice is spring steel.In size design,the main beam of structure is designed to 4cm and slightly wider base,which can get the best effect.To strain monitoring device,many experiments had been done,including tensile experiment and temperature compensation experiment and restorative performance experiment.Test results show that the device has a large dynamic response range,high overall resolution and good restorative performance.The deviation of temperature compensation between two gratings remains within 0.005nm.2.Through overall analysis of transmission line,three kinds of transmission line ice thickness calculation models are established,which are strain difference model,parabolic method combined with BP neural network model and catenary method model.In Hunan Xuefeng Mountain experimental tests were made,then monitoring data of transmission line real-time status by the newly designed sensor was used to verify the accuracy of the three models,and accurate icing results were recorded synchronously as a reference.Experimental results show that strain difference model,parabolic method combined with BP neural network model and catenary method model,which are within 0.5mm of error,are all very close to actual situation.But relatively speaking,the monitoring accuracy of the previous two models is higher than the catenary method model.3.In order to make the catenary method model more accurate,put forward a corresponding optimization program,including establishing a three dimensional model of wind load,designing wind speed monitoring device based on optical fiber grating strain mechanism,and completing simulation experiments.Simulation results show that the impact of wind load can not be ignored,and by using the optimization program on exclusion of wind load,more precise monitoring icing results can be achieved.