The Research Of Distribution Transformer Chopped Impulse Overvoltageproof Reactor

Distribution Transformer is the the electrical equipment which is vulnerable to lightning damage in power system, once subjected to lightning damage will affect the stability of power system operations, and caused direct economic losses to the users. At present, the measure used for distortion transformer lightingproof is not based on consideration of lightning arrester operating chopped impulse attack .The distribution transformer emergency occurred very oftenly, so the power system need research of a new measure for protecting distribution transformer.This article introduced a vision of new type distribution transformer chopped impulse overvoltageproof reactor(NTOR), and proved the lightingproof permance of NTOR. This article also has gave the value of NTOR inductance and made necessary preparation for furture research.The first part of this article introduced detailed mathematical models of lightning waveform and chopped impulse. Then based on the characteristics of ligntning arrester, this article established a mathematical model for describing distribution transformer high voltage side MOV operating chopped impulse overvoltage.The second part established the time domain equivalent circuit of a common distribution transformer and calculated parameters value of the time-domain equivalent circuit according to the technical parameters of distribution transformer. Based on the analysis and comparison of power reactors widely used in power systems, then this article introduced the preliminary vision of NTOR structure.The simulation model based on Simulink state-space block of the language of MATLAB is used to give the image of the transient process of distribution transformer winding with lightningproof and not. It also gave the image of current and voltage waveforms of the first coil and the second coil.Based on the analysis and comparison of the simulation results, this article gave the preliminary inductance parameter value of NTOR. Finally, according to the simulation and analysis of transformer entrance over-voltage, this article further illustrated NTOR restriction performance on the steep of over-voltage and current. This article also verified the theory feasibility of the new lightningproof reactor.