METHOD FOR DETERMINING TECHNICAL STATE OF A DIGITAL TRANSFORMER BASED ON PARAMETERS OF PARTIAL DISCHARGES IN INSULATION Russian patent published in 2019 - IPC G01R31/12 

FIELD: electrical engineering.

SUBSTANCE: invention relates to high-voltage engineering and can be used for diagnostics of technical state of digital transformers. Digital transformer is equipped with a resistive voltage divider and an inductive sensor placed inside the reference insulator. Inductive sensor is connected between electrostatic screen and earthed parts of transformer. Voltage of industrial frequency is recorded by resistive voltage divider. High-frequency voltage pulse from partial discharge current is detected by inductive sensor. Registered signals are filtered and digitized. Phase of high-frequency voltage pulse from partial discharge current is calculated relative to industrial frequency voltage, amplitude and polarity of high-frequency voltage pulse from partial discharge current, number of high-frequency voltage pulses from partial discharge currents during period of industrial frequency voltage change, apparent charge, maximum apparent charge value during observation, average value of apparent charge during observation, average current and power of partial discharges during period of voltage variation of industrial frequency, energy of partial discharge. Performing normalization and Fourier transformation and calculating effective time and frequency of high-frequency pulses. Time-frequency distribution of high-frequency voltage pulses from partial discharge currents is constructed. Amplitude-phase-frequency distribution of high-frequency voltage pulses from partial discharge currents and period of change of industrial frequency voltage are plotted on one graph, from which noise and other discharge processes are separated from internal partial discharges and ranges of phases of occurrence of partial discharges are determined. Dependences of the apparent charge amplitude and the actual value of the industrial frequency voltage on time are plotted, from which the value of the partial discharge ignition voltage and the apparent charge value are determined. Value of apparent charge during observation is compared with threshold value. Results of comparison are used to draw conclusions on possibility of further operation of transformer.

EFFECT: higher reliability of digital transformers.

1 cl, 4 dwg