Research On Field Fault Diagnosis Technology Of Dry-type Air-core Shunt Reactor

Dry-type air-core shunt reactor plays a role in compensating reactive power,restricting over-voltage in the power grid.With the increasing of voltage level,the capacity of dry-type air-core shunt reactor gets bigger,the parallel branches of dry-type air-core shunt reactor gets more and more,the deviation of turns number is hard to avoid during manufacturing,and the broken-wires fault may occur during transporting or running.The existing diagnosis methods are unable to diagnose the defect in reactor.For this kind of problem,this paper presents a method of measuring the distributed current to diagnose defect of reactor,and the measuring device was developed.Based on establishing the circuit model of reactor,and analyzing the electrical characteristics,this paper gives the calculation method of normal reactor and fault reactor circuit model of reactor,and take a BKDK-20000/35 dry-type air-core reactor for calculating.By analytical and simulation method to calculate the running reactor magnetic field,and analyzed the power frequency interference between running reactor and measured reactor.In order to avoid the power frequency interference,this paper designed the 25 Hz power supply to measure reactor,using harmonic analysis and quasi-synchronous algorithm to process the collecting data by acquisition card.The magnetic shielding current sensor is developed for avoiding the effect of magnetic field.Finally the test of reactor was taken for validation.The research results show that,when turn-to-turn short fault,the broken-wires fault and the deviation of turns number occur to dry-type air-core shunt reactor,the total current of reactor changes little and the variation of distributed current is obvious near the fault location.By 25 Hz test power supply use the magnetic shielding current sensor for measuring reactor distributed current,using quasi synchronous sampling and harmonic analysis for processing data,the measurement results is close to the theoretical value.It shows that the 25 Hz test power,harmonic analysis method and quasi-synchronous algorithm has a strong performance of anti-disturbances of power frequency,the distributed current can be measured in high accuracy.