Kazuo Tanabe

Development of Locating System of Pulsed Electromagnetic Interference Source Based on Advanced TDOA Estimation Method

A locating system based on an advanced time difference of arrival (TDOA) estimation method is developed to locate the position of a discharge source to avoid pulsed electromagnetic interference (PEMI) with the surrounding radio communication environment. In general, from the waveforms of PEMI waves received by an antenna array, the source position can be located or the direction of arrival (DOA) of the EM waves can be estimated by applying TDOA-based methods. However, owing to noises and multipath waves that occur at the metal surfaces of electric power equipment, the estimation accuracy of the TDOA may decrease, and the location accuracy will be degraded. To improve the accuracy of TDOA estimation, we propose a new TDOA estimation technique. In our developed locating system, PEMI waves are received by a four-antenna-square array and the DOA is estimated from the TDOA, which is estimated using the generalized cross-correlation phase transform method in combination with the proposed technique. A PEMI source is ultimately located by aiming a charge-coupled device camera, installed at the center of the antenna array, at the estimated DOA. The estimation accuracy of the locating system is evaluated through experimental measurements. The results show that the developed locating system can locate the position of a PEMI source existing within about 30 m from the system with high accuracy.

Experimental study on the prediction of hum noise from conductor bundles for UHV transmission lines

The audible noise produced by corona discharge from transmission line conductors comprises two major components, namely hum noise and random noise. Hum noise has a frequency that is twice the power line frequency and is generated primarily in rain, fog, and highly humid environments. It is one of the major factors affecting the design of conductor transmission lines for voltages above 500 kV, and it is very important to predict the level of hum noise near transmission lines. In this paper, using a comparison between measured values in the UHV Akagi test line and that using corona cage, an experimental prediction method of hum noise in rain condition is proposed.