Research On Comprehensive Protection Measures And Layout Optimization Of Overhead Insulated Lines In 10kV Distribution Network

Lightning is the main cause of overhead line fault in distribution network,which seriously affects the reliability and power quality of the system.In 10 kV distribution network,overhead insulated conductor is widely used.Overhead insulated conductors have the advantages of less land occupation and cost saving,and can improve the safety and reliability of the system operation.However,the frequent lightning break accidents on the conductors have also attracted people’s attention.Through the analysis of the formation of phase to phase arc,heat analysis and stress analysis when lightning strikes overhead insulated conductor,the mechanism of overhead insulated conductor broken by lightning stroke is explained.Under the high lightning impulse current,the overhead insulated conductor is easy to be damaged,and the insulation damage is easy to break down and form phase to phase short-circuit arc;under the large short-circuit current of phase to phase short-circuit,the overhead insulated conductor is continuously burned by the power frequency continuous current arc and under the action of multi-directional force,and the line breaking accident occurs orderly.At present,the measures to prevent overhead insulated conductors from lightning stroke are generally based on the principle of "Dredging" and "blocking".Through lightning protection measures to improve the lightning withstand level of lines and reduce the probability of breakdown arc,the occurrence of lightning break can be effectively reduced,which plays a good role in the protection of distribution lines.The measures to improve the lightning withstand level and reduce the Flashover Rate of transmission lines are as follows:installing lightning arresters,installing puncture type arc protection fittings,erecting inductive lightning shielding wire,etc.In this paper,the mixed integer linear programming(MILP)model is used to optimize the three kinds of protection methods,i.e.erection of lightning conductor,installation of lightning rod and arrester.The model considers the combination optimization of different protection measures in the line,and optimizes the reliability index of distribution network under the given cost constraint.In this paper,a practical distribution network is taken as an example,and the algorithm is applied to optimize the simulation results of 80 reference lines.It can be seen that the SAIFI value of combined protection is smaller than that of single protection under the same economic input,that is,the impact of lightning break accident is smaller.