Study On Electric Unbalance Degree Of Multi Circuit Transmission Lines Of Mumian Substation In Guangzhou

With China's reform and opening up,economic development throughout the country,the rapid growth in demand for electricity,resulting in high-voltage line construction and limited land resources between the more and more prominent.So the use of the same tower on the multi-loop transmission line(referring to the same transmission line towers and double back or even multi-loop transmission line),thereby compressing the overhead line construction land required area,improve the unit line corridor power transmission capacity is more The more important.However,with the application of multi circuit transmission on the same tower,the unbalance problem is more and more outstanding,Due to their non transposition or non incomplete transposition,it will produce a large imbalance voltage and imbalance current,and the negative sequence and zero sequence component produced by imbalance will bring the polar harm to the safe and stable economic operation of power system,therefore,it is significant to study the electric unbalance degree of the multi circuit transmission lines on the same tower to ensure the stable operation of the power system.Guangzhou is located in the center of the Pearl River Delta,is one of China's economic core area,the transmission line corridor resources have been very scarce,transmission lines on the same tower or the same corridor as the parallel erection of the site is very common,it is of great engineering significance to study the unbalanced degree of the multi circuit transmission lineson the same tower in Guangzhou area,and to put forward the optimization method of the electric unbalanced degree of transmission lines.This paper take the 16 circuit transmission lines of Guangzhou mumian substation as the research object,which relates to the single line,double circuit lines on the same tower and four circuit lines on the same tower.The circuit is complex,the structure of the wire,the direction of the line,the running conditions and so on are different.In order to analyze the electric unbalance degree of the complex circuit,this paper proposes a simulation model of the multi circuit by using the SIMULINK module in MATLAB software.The 16 lines are divided into 25 sections according to the distance and the parallelism,the line parameters of each section are calculated,positive sequence voltage is loaded at the head of the line,then the electric unbalance degree of each circuit is obtained by software simulation.The result shows that,under the current economic,the electric imbalance degree of lines meet the requirements,but under the maximum current,the electric unbalance degree of part of the line is high or does not meet the requirements,which need to optimize the electric unbalance degree.To this end,the phase sequence adjustment method is proposed.This paper calculates the electric unbalance degree of 36 kinds sequence adjustment of the 16 circuit transmission lines,through the calculation results,the best 3 schemes are found out.But considering the feasibility and economy of engineering construction,the optimal phase sequence adjustment is found out.The results of this study has important significance to improve the electric unbalance degree of mumian substation,it also has certain guiding significance to the design and erection of other transmission lines of the same tower in our country.