Research On Temperature Rise Of Grounding Resistance Of Distribution Network Fault Location System In Plateau Environment

Distribution fault location system mostly adopts resistance switching method.The resistor will flow through a specific series of currents when locating the fault point.Due to the current thermal effect,the resistor will generate a large amount of heat,causing the temperature to rise.Overheating of the resistor can affect its performance and life.The resistivity of the resistor is highly correlated with temperature.If the temperature of the resistor is too high,the resistance value of the resistor increases greatly,which affects the current characteristics of the injection loop,which is not conducive to signal detection.The resistors studied in this paper are located in the signal source and rely on air to dissipate heat.The national standard stipulates that the short-term temperature rise limit of stainless steel resistors in the plain area is 760 K,and the research on the temperature rise of resistors at home and abroad is mostly based on the plain area.Usually,altitudes above 1 km can be considered as plateaus.Since more than 26% of China’s regions are plateaus,the environment in the plateau is harsh,and the air pressure,relative humidity and absolute humidity are lower than those in the plain area,which is not conducive to the heat dissipation of the resistors.Therefore,the temperature rise in the plateau environment is different from that in the plain area.This paper begins to study the temperature rise of the grounding resistor of the distribution network fault location system in the plateau environment.The main contents are as follows:(1)In order to extract the current value of the resistor when it is put into operation,and to analyze the influence of the resistance value on the signal source injection current sequence characteristics,Simulink is used to model and simulate the single-phase ground fault location system of the distribution network.(2)Using Ansys to establish a simulation model of grounding resistor heat transfer,calculate the convective heat transfer coefficient of the resistor surface according to the air parameters in different altitude environments,and consider the influence of thermal radiation on the temperature rise of the resistor,combined with the specific injection when the fault occurs.The current sequence simulates the temperature rise of the resistor at different altitudes.(3)In the altitude environment of 1901 m,the grounding resistor temperature rise measuring system is designed to simulate the current flow condition of the resistor after single-phase fault,and the temperature rise of the wire-wound stainless steel grounding resistor is tested,and compared with the results of Ansys simulation.