A Sensor System for Detecting and Localizing Partial Discharges in Power Transformers with Improved Immunity to Interferences

Abstract

The paper reports on the solution, principles, and application results related to a system for diagnosing main transformers in power plants via the radiofrequency method. The subject of the diagnostics is the occurrence of partial discharge activity in transformers. The technical solution of the system is characterized in the introductory section of the article. There then follows a description of the operating principle and the implemented novel advanced methods for signal detection and source localization. The results obtained from practical application of the system within the diagnostics of high-power transformers are presented as well. Because ambient electromagnetic disturbance was recognized as a major issue during the system development, novel detection methods were proposed, implemented, and verified. The principal approach utilizes an external radiofrequency sensor to detect outer impulse disturbance and to eliminate disturbance-triggered acquisitions, and it also ensures direct real-time visualization of the desired impulse signals. The ability of weak signal detection was verified via artificial impulse signal injection into the transformer. The developed detection methods were completed with localization techniques for signal source estimation. The desired impulse signal was detected and localized during full operation of the main transformer, despite the presence of strong electromagnetic interference.

Application of Prandtl’s Theory in the Design of an Experimental Chamber for Static Pressure Measurements

“…The DPS+ pressure sensor is characterized by excellent long-term stability, linearity and repeatability. Therefore, it is suitable for our experiment [ 32 , 33 ].…”

Modeling and Experimental Verification of Plasma Jet Electromagnetic Signals

“…To describe, evaluate, and analyze the conditions outside the plasma channel, we used a wave-theory-based numerical model formulated from the reduced Maxwell equations [12][13][14]. The model was conceived as a fully non-stationary problem defined on the basis of the telegrapher's equations [32,33]. The results obtained in the analyzed simple model are presented in Figure 2b,c, the monitored quantities being the volume loss P vol in the area of the channel and the intensity of the electric field E. In the model, the plasma channel was substituted with a "macroscopic" counterpart; the main benefit of this approach rests in capturing the overall interaction of the plasma and the external electromagnetic field.…”

Extraction of Partial Discharge Signal in Predominantly VHF Frequency Range in the Presence of Strong Noise in Power Transformer

“…In [7,24,25,31] the dominant noise was in the higher frequency range than PDs. In [32], the source of interference was located on one of the high-voltage bushings through which the transformer from the turbogenerator is fed. The artificial impulse simulated the EM radiation of PDs in view of its waveform, time duration, and spectral composition.…”