Research Of AC Superimposed Pulse Oscillation Equipment And Its Destruction To Interturn Insulation Of Reactors

Dry-type air-core shunt reactor in power system is easy to withstand reburning overvoltage during switching,which may lead to interturn insulation breakdown and burnout accidents.The reburning overvoltage is mainly a voltage waveform that pulse oscillation is superimposed at the peak of AC voltage.It is of great significance for the manufacture and protection of dry-type air-core reactor to study the destructive effect of reburning overvoltage on the turn-to-turn insulation of dry-type air-core reactor by experiment.In this paper,a main circuit of AC superimposed pulse oscillation high voltage test equipment is presented,and the parameters of relevant components are determined.In order to make the pulse oscillation voltage superimposed at the peak of AC voltage twice per second,a set of gap discharge control circuit is proposed,which is made into PCB circuit board,and its feasibility is verified by experiments.The whole equipment is constructed to verify the output voltage waveform.Using the equipment,The instantaneous withstand voltage test and aging life test under pure AC,pure pulse oscillation and AC superimposed pulse oscillation voltage are carried out to investigate the destructive effect of AC superimposed pulse oscillation voltage on dry-type air-core reactor interturn insulation.The results show that the main circuit of the AC superimposed pulse oscillation test equipment proposed in this paper can realize the superposition of AC and pulse oscillation.The proposed gap discharge control circuit can generate two thyristor trigger pulses at the peak of power frequency AC voltage every second.The built AC superimposed pulse oscillation test equipment can output the voltage waveform that pulse oscillation is superimposed at AC peak and the pulse oscillation voltage is superimposed at the peak of power frequency AC voltage twice a second.Under the superposition voltage,the higher the AC component,the lower the pulse oscillation voltage when the sample breaks down.However,when the AC voltage component increases,the peak value of breakdown voltage is basically stable at 21 kV,which is the same as that when the pulse oscillation voltage is applied alone.When the peak voltage is constant,the damage of pure AC voltage to the interturn insulation of reactor is much greater than that of AC superimposed pulse oscillation voltage to the interturn insulation of reactor.When the peak value of the superimposed voltage is constant,the higher the AC component is,the more destructive the superimposed voltage is to the insulation.When the peak voltage is greater than 10.5kV,the damage of pure pulse oscillation voltage to interturn insulation is much greater than that of low AC component superposition voltage with the same peak voltage to turn-to-turn insulation.