The invention relates to the technical field of power
transformer state monitoring, and discloses a main
transformer winding temperature rise on-line monitoring method and
system, and the method comprises the steps: obtaining the calibration
flight time of ultrasonic
waves through an
acoustic sensor array disposed on the outer wall of an
oil tank in a quasi-isothermal state of a
transformer; calculating a structure additional time
delay which is caused by an internal fixed structure and does not change along with the temperature, and establishing an
acoustic fingerprint for the transformer; during on-line monitoring, oil way net
propagation time reflecting temperature change of the insulating oil is obtained from on-line
flight time measured in real time; and then, based on the net
propagation time of the oil way, an acoustic
tomography algorithm is adopted to reconstruct internal two-dimensional or three-dimensional temperature field distribution, and the winding hot-spot temperature is finally and accurately calculated in combination with the real-time load current. According to the invention, through the
acoustic fingerprint correction technology, the measurement interference of an internal fixed structure is eliminated, and non-intrusive, high-precision and visual online monitoring of the winding hot-spot temperature is realized.