Development Of A New 35kV Distribution Line Surge Arrester Frequency-Dividing Disconnector

Lightning accidents in the distribution network seriously affect the power supply reliability of power systems.Zinc oxide lightning arrester is usually installed in engineering to enhance the lightning withstand level of the electric line.But the insulation of the arrester damage is hard to be found,which will cause line grounding faults.With disconnectors installed,when the insulation of the arrester is damaged,the line grounding fault would be removed by disconnectors in time,which is convenient for operators to find the fault section,eliminating the lines shortage in time and reducing the workload of the operation and maintenance of the arresters.In this paper,taking 35kV distribution line arrester disconnector as research object,a structure of new frequency-dividing disconnector is proposed after in-depth research on the overall design,local optimization and reliability measurement,in view of situations such as generally unsatisfactory operating condition of the existing disconnector,inadequate disconnector performance to meet the actual needs of the power grid,operation failure of disconnector when arrester insulation is damaged and operation of disconnector when arrester insulation is intact.Firstly,the arc magneto-hydrodynamic(MHD)model of the gap is established based on COMSOL software to determine the key parameters of the split-frequency disconnector,and the operating characteristic of the design are verified by ATP software.Then,through analyzing the temperature and electric field distribution characteristics of the gap in different shapes and materials by COMSOL,local optimizations of spark gap and discharging gap are performed.Finally,the correctness and feasibility of the preliminary design and optimization are verified by conducting the field test of the new split-frequency disconnector.Research results and field tests show that the split-frequency disconnector has the inverse time action characteristics.When power current flows through the arrester with insulation fault,the larger the current,the faster the disconnector action,and when the frequency current is greater than 100A,disconnectors action within a few milliseconds,realizing the fast disconnect of fault arrester,and improving the operating stability of the power system to a certain extent.