Design And Application Research Of Ultra-low Frequency High Voltage Signal Generator

A large number of XLPE cables are more and more widely used in urban power grids.If cables with insulation defects cannot be found in time,the safety of the entire power system will be further affected.However,the traditional withstand voltage test is difficult to be widely used in the field test of XLPE cable,and there are problems such as damage to the cable,large volume and low operation safety.In view of the above problems,this paper designs a new type of portable ultra-low frequency high voltage signal generator,the generator is used as the detection power supply to carry out the withstand voltage test on the cable,The generator is controlled by the program together with the detection circuit to realize the output of the sine wave voltage.And further realize the miniaturization of the ultra-low frequency high voltage signal generator,the main work is as follows.Firstly,this paper realizes the output of ultra-low frequency sine wave high voltage voltage based on DSP program control and detection circuit,and gives the design principle of ultra-low frequency cosine square wave.Mainly complete the design of the main circuit and the control system.The main circuit includes rectifier circuit,inverter circuit,highfrequency transformer,bridge voltage doubler rectifier circuit and detection circuit,etc,and select the relevant components of the main circuit.The DSP28035 is used as the main chip of the control system,the A/D conversion chip processes the collected signals and sends them to the DSP,and outputs the PWM phase-shifted drive signal to the drive circuit to control the on-off of the IGBT,and at the same time,the output envelope of the inverter circuit is an AC voltage with a sinusoidal waveform.Then,the simulation model of the ultra-low frequency high-voltage signal generator is built using the MATLAB/Simulink simulation platform,and the simulation verification of each part of the DC high-voltage power supply is carried out respectively,and the simulation verification of the entire ultra-low frequency system is carried out.The simulation results show that the generator design is reasonable and correct.On the basis of the actual design and simulation of relevant parameters,the principle prototype is made,and the output test of the sine wave voltage is carried out.Finally,the main shortcomings of the traditional withstand voltage test are analyzed.Compared with other withstand voltage tests,the ultra-low frequency withstand voltage test has advantages,such as no damage to the cable,small size and high operational safety.And based on the application analysis of ultra-low frequency high voltage signal generator to the pressure test of XLPE cable.