Research on the online measuring technology of inter-turn insulation of dry air-core reactor

Abstract

The fault model of the inter-turn short circuit of the dry air-core reactor is first analysed in this study, by which an online monitoring method of the reactor inter-turn insulation fault is proposed by using the change of the power angle. In order to achieve high-precision measurement, the fundamental harmonic separation algorithm improved by Hanning windowed interpolation method can effectively reduce the error of power angle measurement caused by frequency fluctuation and harmonic interference. By comparing it with the power angle measurement errors of fast Fourier transform (FFT) and Hanning window interpolation FFT, the algorithm is verified. The sensitivity and stability of the equipment are verified by the experiment of simulating and eliminating the fault in the initial stage of the inter-turn short circuit. At the same time, an online monitoring system for inter-turn insulation fault of dry-type air-core reactor based on this method is designed, including field monitoring device, the intelligent electronic device of the dry air-core reactor and expert software. The method and monitoring device proposed in this study enables the fault to be accurately monitored in the early stage, which is of great significance for the safe operation of the reactor.