Research On The Macro-model For Calculating Lightning Induced Overvoltages On Overhead Lines And Its Interface With Simulink

Lightning accident is one of the important causes of power supply interruption in the power system,and the most cause is the lightning induced overvoltages.Supported by the Fundamental Research Funds for the Central Universities project "Field-Circuit Coupling Problem Hybrid Modeling Method and Simulation Technology"(Grant No 2017MS100),the question of lightning induced overvoltages on overhead lines based on port model in MATLAB/Simulink is studied.The main research achievements are presented as follows:1.This paper presents a macro-model which can be used to calculate the lightning induced overvoltages(LIOVs)on overhead lines according to the Agrawal's field-to-line coupling model,in which the distributed equivalent voltage sources due to the horizontal components of the incident electric fields are lumped at the terminals of the transmission lines.In order to interface with MATLAB/Simulink,the frequency parameters are approximated by the vector fitting(VF)method,and then described by a state-space representation,compared with the time domain method of calculating lightning induced overvoltage in overhead lines,the model is simple.Based on this model,the induced lightning overvoltages of the one or three phase overhead distribution line system considering the earth resistivity are calculated,and the results are compared with the time domain finite element method to explain the correctness of this method.2.Based on the MATLAB/Simulink circuit simulation software,a circuit model for calculating the lightning induced overvoltages is established,which can easily handle the complex distribution networks and nonlinear elements.In this paper,ground wires and arresters are added to the multi-conductor transmission line to analyze their protective effect on lightning induced overvotages in the circuit port model.3.In order to calculate the lightning induced flash-over rate,a simple port model to calculate the peak value of the lightning induced overvoltages on overhead lines is proposed,in which reflect current sources at the end of the line are ignored as long as the time delay from one end to other would be greater than the rising timeof LIOVs.Based on this model,the electric geometric model and Monte Carlo method are used to calculate the lightning induced flash-over rate,which can better analyze the lightning protection level.