Study On Ferroresonance And Characteristic Parameters Of ZnO For Its Suppression Method In Distribution Network

With the rapid development of economic,the power consumption has increased gradually.The safe and stable operation of the power grid are challenged for higher requirements.However,with the increase of power cable in urban distribution network,capacitance of system also increase gradually.The duration of ferroresonance overvoltage caused by the iron core of electromagnetic voltage transformer saturated lasts longer.It seriously damage electrical equipments and even seriously affect the safe operation of the power system.Therefore,studying ferroresonance phenomenon in distribution network and seeking for a stable and reliable harmonic elimination measure are of very important theoretical significance and engineering practical value.Combining with the features of ferroresonance overvoltage,a new neutral point grounding way to inhibit ferroresonance overvoltage is studied in this paper.Firstly,ferroresonance overvoltage principle is analyzed in power distribution.Different characteristics of the ferroresonance overvoltage is studied in different grounding capacitances and different fault durations.Secondly,the spectrum and phase track diagram of different ferroresonances are analyzed by nonlinear dynamic.Thirdly,according to the characteristic of ferroresonance overvoltage,system neutral point through ZnO nonlinear resistance to inhibit ferroresonance overvoltage is studied.And the determination method that parameter characteristics of ZnO nonlinear resistance is studied.Finally,the characteristics of ferroresonance overvoltage are analyzed in a 10 kV power distribution system that is built by ATP-EMTP and MATLAB.A large number of simulation tests for the suppression method of system neutral point through ZnO nonlinear resistance are conducted.Test results show that the analysis of various characteristics of ferroresonance is correct,and the method that obtain parameter characteristics of ZnO nonlinear resistance is reasonable.The way that system neutral point through ZnO nonlinear resistance to inhibit ferroresonance overvoltage is effective.