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In order to suppress random pulse interference in field detection of partial discharge in power equipments, pulse features is extracted using equivalent time-frequency analysis. Based on adaptive fuzzy clustering of the features, concentration degree of phases is used as the indicator to distinguish partial discharge signal from pulse interference. The results of field data analysis indicate that our method can effectively remove random pulse interference in partial discharge signal. This study provides good theoretical and practical basis for insulation state assessment in power equipments.

The detection and diagnosis of partial discharge (PD) has been accepted as one of the most valuable means for assessing the quality of high voltage (HV) power apparatuses and their operating status. However, the present partial discharge monitoring methods are mainly based on monitoring single equipment, which needs multi-process test equipment, high cost, and huge maintenance engineering. In this paper, a method using a four element antenna array to receive the ultra-high frequency (UHF) signal, which is used to define a 3-D coordinate system and locate the PD source in the field of substations, is proposed. Moreover, this paper discusses the principles of the location algorithm based on time difference, and analyzes the origin of its location error. Then the relationship between the location error and the placement of antenna array, as well as the relationship between the location error and the time difference of arrival signals are discussed theoretically. Finally, this paper provides an optimal placement to the radio frequency antenna array.

The selection of measuring points is an important problem for the vibration monitoring of transformers. The paper analyses the corresponding selecting principles. A series of experiments were conducted in one 220kV transformer with fixed-frequency variable current. The experimental results showed that the measuring points should be placed on the base of windings and the side wall of the tank. Another experiment was conducted with variable-frequency fixed-current. The results showed that different exciting frequency was important for choosing measuring points. Finally, three selecting principles were summarized.