Study of the Influence of Winding and Sensor Design on Ultra-High Frequency Partial Discharge Signals in Power Transformers

Abstract

Ultra-high frequency (UHF) partial discharge (PD) measurements in power transformers are becoming popular because of the advantages of the method. Therefore, it is necessary to improve the basic understanding of the propagation of signals inside the transformer tank and the factors that influence the sensitivity of the measurement. Since the winding represents a major obstacle to the propagation of the UHF signals, it is necessary to study the effect of winding design on signal propagation. Previous research activities have studied these effects using simplified models, and it is essential to consider the complexity of propagation in a complete transformer tank. Additionally, the quality of UHF PD measurements depends, to a large extent, on the sensitivity of the UHF sensors. In this contribution, a simulation model consisting of a simple, grounded enclosure with multiple winding designs is used to study the propagation characteristics of UHF signals when an artificial PD source is placed inside the winding. After analysis of the results, the winding designs are incorporated in an existing and validated simulation model of a 420 kV power transformer and analyzed to observe the influence in a more complex structure. Two commonly used sensor designs are also used in the simulation model to receive the signals. In all cases, the propagation and signal characteristics are analyzed and compared to determine the influence of the winding and sensor design on the UHF signals. It is found that the level of detail of winding design has a significant impact on the propagation characteristics. However, the attenuation characteristics of the UHF signals received by the two sensor designs are similar, with the electric field distribution around the sensor being the key difference.

Research on On-Line Detection Method of Transformer Winding Deformation Based on VFTO

“…At present, there are many studies on the transient circuit model of transformer winding at high frequency, mainly including the multi-conductor transmission line model that takes each turn of transformer winding as a transmission line, the uniform transmission line model that combines single-conductor and multi-conductor transmission lines, and the mixed model of a multi-conductor transmission line and concentrated parameter [23][24][25][26]. However, the calculation of a multi-conductor transmission line model is large, and the error of the uniform transmission line model is large.…”

“…In Reference [25], the variation of the equivalent circuit parameters of the winding corresponding to the faults of the winding axis deviation, radial deformation, and the change of inter-cake spacing is simulated, as shown in Table 5. The fault diagram of winding axial offset, radial deformation, and disc spacing change is shown in Figure 9.…”

Non-Contact High Voltage Measurement in the Online Partial Discharge Monitoring System

“…For this reason, in the last dozen or so years, the intensity of work on the development of online partial discharge monitoring systems has been increased [9][10][11][12][13]. These systems most often use the acoustic emission (AE) method or electromagnetic methods for recording signals in the high frequency (HF), very high frequency (VHF), and ultrahigh frequency (UHF) radio frequency bands [14][15][16][17][18][19]. However, due to the high purchase and maintenance costs, monitoring systems are relatively rarely installed permanently.…”

Assessment of Rogowski Coils for Measurement of Full Discharges in Power Transformers

“…Therefore, several techniques were developed to perform discharge diagnoses such as the UHF approach [7], acoustic analysis [8], optic acoustics technology [9], etc. Among these previous methods, one of the most promising discharge detection technique is the analysis of the transformer's current signals [10], which can allow the identification of incipient discharges.…”