| The high reliability of the distribution line is an important guarantee for the normal power supply of the power system.However,the voltage level of distribution lines is low and the insulation level of lines is not high,which is prone to lightning trip and power failure.Especially in certain mountainous areas,where the soil resistivity is high and lightning activity occurs frequently,trips and blackouts caused by lightning on lines account for 50%-70%of the entire distribution system,which seriously affects the normal power supply of the power system.Therefore,studying how to improve the lightning protection performance of distribution lines in mountainous areas plays a vital role in the safe and stable operation of power systems.At present,the lightning protection level of the line is improved and the power supply reliability of the line is enhanced mainly by setting up lightning arresters or installing lightning arresters.But which method is more effective for lightning protection of distribution lines?So far,there are few data at home and abroad to analyze this problem.This paper takes 35kV power distribution line in mountainous area as an example,through modeling and simulation,quantitatively analyzes and compares the lightning protection effect after installing lightning protection line and line arrester,which provides a theoretical reference for lightning protection design of mountainous distribution line.Firstly,the mechanism of lightning strike 3 5kV line is studied,and the existing lightning protection measures and their existing problems are analyzed.Then through the on-site investigation,the specific parameters such as the conductor of 35kV line,the size of the tower and the grounding resistance of the tower are obtained.Using electromagnetic transient simulation software(ATP-EMTP),equivalent simulation models were built,including:lightning current model,tower model,grounding resistance model,line model,insulator flashover model,and lightning arrester model.Based on the simulation model of multi-level tower,the lightning protection effects of installing lightning conductor,installing line lightning arrester,installing lightning conductor and line lightning arrester in different lightning stroke modes are analyzed quantitatively.The simulation results show that the installation of line arresters can reduce the tower shunt coefficient and suppression coefficient,effectively improve the line lightning resistance,and its effect is better than the installation of lightning conductors.In addition,through numerical comparison,the effects of grounding resistance,lightning current amplitude and lightning conductor height on the tower shunt coefficient,arrester shunt coefficient,and suppression coefficient were quantitatively analyzed.The analysis results show that when the grounding resistance of the tower is constant,by reducing the grounding resistance of the arrester,the lightning resistance level of the line can be more effectively improved.Based on the above research and analysis and the specific conditions of the line,in the field example modification,the scheme of connecting the multi-level tower lightning arrester grounding device is adopted to complete the lightning protection transformation construction of the 35kV distribution line to further reduce the grounding resistance of the arrester.And analyze the influence of the number of grounding devices on the transformation effect.The lightning protection effect of this line shows that the theoretical analysis and lightning protection scheme of this paper can greatly improve the lightning resistance level of the line and enhance the reliability of line power supply. |
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