Analysis On The Effect Of Stator Interturn Short Circuit On Core Temperature Rising Characteristics Of Generator

The large-scale turbine generator is the key component of heat-engine plant.In the ‘Made in China 2025’ strategic program,it clearly puts forward the requirements to improve the manufacturing level of various types of generating sets,especially large capacity generating sets and other power equipment.Static air-gap eccentricity(SAGE)and stator interturn short circuit(SISC)are common mechanical and electrical faults.Under the current technical level,it is of great significance to study the characteristics of core loss and the law of temperature rising under high frequency and complex working conditions.The active prevention and heat-sink cooling structure of iron core insulation damage will be beneficial for this study.This thesis presents a comprehensive analysis on the core temperature rising characteristics in normal,SAGE,SISC,and the combined faults(SAGE & SISC),respectively,in generators.The primary work and the main research results are as follows:(1)The characteristic of air gap magnetic density and core loss are analyzed.The air gap magnetic density and core loss theoretical formula under normal,SAGE,SISC and combined faults are deduced by using magnetomotive force(MMF)multiplying permeance per unit area(PPUA)method and bertotti trinomial constant coefficient iron loss calculation model.Not noly the characteristics of air gap magnetic density and core loss,but also the impact of different SISC degrees and different positions on the core loss are studied.The qualitative properties for the temperature rise characteristics of the stator and rotor iron cores are provided.Besides,the theoretical analysis correctness was verified by finite element analysis(FEA).(2)The core temperature rising characteristics of generator under SISC faults are studied by FEA.The iron core temperature rising characteristics of generator driven by magnetic-thermal coupling is established.Besides,the influence of different SISC degrees and SISC positions on iron core temperature rising characteristics are analyzed.The results are shown that the more SISC degree is,the more iron core temperature rising will be.Specifically,the highest temperature of the rotor core is located on the inner surface of the contact between core and shaft,and the lowest temperature is located on the outer surface of the contact between core and air.The highest temperature of the stator core is located on the inner surface,and the lowest temperature is located on the stator core end face.When combined faults happened,the closer the short circuit position is to the minimum air-gap point,the more severe the stator and rotor core temperature rising will be.(3)The iron core temperature rising characteristics of generator experiment study are carried out.The iron core temperature rising dates under different conditions are collected.Comparing the experimental results with the FEA results,the impact of different SISC degrees and positions on iron core temperature rising characteristics in generator are verified.