The design and field application of transformers on-line detection device based on the wide-band method

Comparing with the traditional IEC pulse current detection method, wide bandwidth pulse current method can reflect the impulse´s real features due to its very wide bandwidth and large amount of information. So a wideband transformer partial discharge (PD) online monitoring system is introduced in this paper, it consists of wideband current sensors, amplifiers, filters, a 50Hz phase generator, a digital oscilloscope and a computer. The wideband current sensors´ measuring bandwidth ranges from 20 kHz to more than 80 MHz; the computer controls the whole data collection process and the software platform was developed using the Labview. All the equipment in this system can be powered by batteries; the 50Hz phase generator can provide the references phase instead the 220V AC power source. The signals obtained by the current sensors are sent into the digital oscilloscope after being amplified and filtered as needed, then comprehensively adopt the Fourier series method and the equivalent time-frequency method to estimate the interference of the original data. This system has been tested both in the laboratory and on the real transformers without power cut and has been proven to work effectively.