Method Of Discriminating Inter-turn Short Circuit Fault Of Air-cored Reactor Based On Frequency Domain Characteristics

Dry-type air-core reactors are widely used in power systems because of their simple structure,low maintenance and constant reactance.Most dry air core reactor failures are caused by intertum short circuit.Therefore,it is necessary to study the effective and accurate detection method of inter-turn short circuit faults in dry-type air-core reactors.At present,the commonly used method of detecting short circuit faults in dry-type air-core reactors is the high-frequency pulse voltage method.This method judges the short-circuit condition of the reactor in the interturn by detecting and comparing the pulsed oscillating voltage waveform under two different voltage types.However,the time domain waveform of the response voltage alone can't intuitively determine whether a short-circuit fault occurs between the reactors in the process of data processing and judgment,and the time domain waveform needs to be further processed.To solve this problem,this paper establishes a short-circuit fault detection model for air-core reactors,which optimize the method of pulse voltage detection for inter-turn short circuit faults.A method for judging short-circuit faults in reactors based on comparison of frequency domain characteristics is proposed,which is fourier transform for the voltage response of a pulsed tank.The frequency domain waveform characteristic through Fourier transform(the voltage amplitude spectrum curve)defines the inter-turn dry fault of a dry-type air-core reactor.The fault degree of the air-to-coil short-circuit of the air-core reactor is judged according to the overall degree of deviation from the normal curve of the voltage curve of the reactor voltage measured in the amplitude spectrum curve.It is verified that this method can more accurately and conveniently determine whether the reactor has a short circuit and short-circuit fault through an example analysis.In order to further determine fault locations in the inter-turn short circuit,a reactor equivalent model was established.Calculating the inductance value of short-circuit faults in different positions of dry air core reactors by using finite element analysis method.In the established reactor model,the inductance model of the reactor in the case of a short-circuit at a different location is assigned,and the time-domain waveform is obtained by a simulation model of the inter-turn short-circuit fault detected by the high-frequency pulse oscillating voltage method.The frequency domain characteristics of the voltage response at different positions of the reactor are obtained after the Fourier transform to the analysis of the attenuation frequency characteristics.By analyzing the characteristics of the frequency domain,the locations of reactor short-circuit faults can be determined.In this paper,the analysis of frequency domain characteristics of the air-core reactor voltage response waveform can determine the fault degree and fault location of the inter-turn short circuit more conveniently and effectively.It is convenient to accurately and accurately handle the short circuit fault of the air-core reactor and improve the safety and stability of the power grid.