scholarly journals New model of explanation for phase angle pattern of online partial discharge measurement in winding insulation of turbine generator

2021 ◽  
Vol 72 (1) ◽  
pp. 66-77
Author(s):  
Abdulrahman Baboraik ◽  
Alexander Usachev
Keyword(s):  
Computer Simulation ◽  
Phase Angle ◽  
Partial Discharge ◽  
Stator Winding ◽  
Monitoring Methods ◽  
Turbine Generator ◽  
Stator Core ◽  
Element Analysis ◽  
On Line ◽  
The Impact

Abstract On-line partial discharge (PD) measurement in electrical insulation of the turbine generator (TG) is an essential approach to control the quality of insulation and to avoid any undesired shutdowns of TG. Although in the last few decades the number of research in PD on-line monitoring methods in the stator winding of TG has increased significantly, it is still not clear yet why PD only appears at certain phase angles of the AC cycle in the phase resolved partial discharge (PRPD) pattern. Moreover, there is not yet any clarification on how the winding configuration of stator may affect PD phase angle pattern. For this reason, this work examines detailed study of the impact of the winding diagram on PD occurrence in the stator winding of real turbine generator class TVF-60-2 (60 MW, 10.5 KV). In addition, a computer simulation of various sizes of ellipsoidal cavities from 0.1 to 2.5 mm between conductor bar and stator core were carried out by using Laplaces equation in Finite Element Analysis (FEA) software ComSol to investigate the relation between the cavity size and coefficient of electric field. As a result of that, the phase angle of PD occurrence in the stator winding will highly depend on the configuration of bars connection, and the computer simulation has helped identifying the PD inception voltage and applied voltage of various ellipsoidal defects size. These two results have helped proposing an initial new theoretical model of explanation the relationship between voltage distributions and phase angle of PD occurrence to determine the degradation level of insulation caused by ellipsoidal defects in the insulation bars of the stator winding which can be used for stator windings of TG rated 6 kV and higher. This model is the initial step to develop a further comprehensive model of explanation for PRPD patterns which will consider all other types of defects as well as the space charge effects from the previous PD.

scholarly journals Novel Features and PRPD Image Denoising Method for Improved Single-Source Partial Discharges Classification in On-Line Hydro-Generators

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3267
Author(s):  
Ramon C. F. Araújo ◽  
Rodrigo M. S. de Oliveira ◽  
Fernando S. Brasil ◽  
Fabrício J. B. Barros
Keyword(s):  
Image Denoising ◽  
Recognition Performance ◽  
Partial Discharge ◽  
Classification Performance ◽  
Partial Discharges ◽  
Denoising Method ◽  
Internal Parameters ◽  
On Line ◽  
Automatic Removal ◽  
The Impact

In this paper, a novel image denoising algorithm and novel input features are proposed. The algorithm is applied to phase-resolved partial discharge (PRPD) diagrams with a single dominant partial discharge (PD) source, preparing them for automatic artificial-intelligence-based classification. It was designed to mitigate several sources of distortions often observed in PRPDs obtained from fully operational hydroelectric generators. The capabilities of the denoising algorithm are the automatic removal of sparse noise and the suppression of non-dominant discharges, including those due to crosstalk. The input features are functions of PD distributions along amplitude and phase, which are calculated in a novel way to mitigate random effects inherent to PD measurements. The impact of the proposed contributions was statistically evaluated and compared to classification performance obtained using formerly published approaches. Higher recognition rates and reduced variances were obtained using the proposed methods, statistically outperforming autonomous classification techniques seen in earlier works. The values of the algorithm’s internal parameters are also validated by comparing the recognition performance obtained with different parameter combinations. All typical PD sources described in hydro-generators PD standards are considered and can be automatically detected.

scholarly journals On-Line Partial discharge Detection of Turbine Generator using GHz-Band Spatial Phase Difference Method

1998 ◽  
Vol 118 (11) ◽  
pp. 1243-1248 ◽  
Author(s):  
Masatake Kawada ◽  
Zen-Ichiro Kawasaki ◽  
Kenji Matsu-ura ◽  
Satoru Kuroki ◽  
Teruya Osawa ◽  
...  
Keyword(s):  
Phase Difference ◽  
Difference Method ◽  
Partial Discharge ◽  
Turbine Generator ◽  
Spatial Phase ◽  
On Line ◽  
Discharge Detection

Development of a Turbine Generator Stator 3D Thermal Model Taking into Account Gas Dynamics

Vestnik MEI ◽  
2021 ◽  
pp. 75-82
Author(s):  
Vitaliy V. Ryzhov ◽  
◽  
Pavel A. Dergachev ◽  
Ekaterina P. Kurbatova ◽  
Oleg N. Molokanov ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Gas Dynamics ◽  
Thermal Model ◽  
Thermal Conductivity Coefficient ◽  
Stator Winding ◽  
Insulation System ◽  
Turbine Generator ◽  
Stator Core ◽  
Equivalent Thermal Conductivity ◽  
Generator Stator

The construction of a thermal model of a fully air cooled turbine generator stator with taking into account gas dynamics is considered. The complete mathematical model includes various physical subsystems with multiphysical relationships. The study is based on accurate 3D models with the use of the modern and proven COMSOL Multiphysics software, in which the finite element method is used for calculation. The equivalent thermal conductivity of the gap between the winding bar copper conductors and stator iron is studied. The gap in question consists of the winding bar main insulation and a gap filled with additional semiconducting gaskets or similar materials. The above-mentioned physical parameter has a strong influence on the temperature distribution, because the main part of the heat releasing in the bar is transferred to the stator core through these elements. The optimal minimum equivalent thermal conductivity coefficient is analyzed and selected. A model of a turbine generator stator symmetric element together with a turbulent cooling air flow is developed and analyzed. The development of such integrated models will make it possible not only to simplify the design process, but also to analyze various insulation systems. For example, air-cooled turbine generators initially use the Global VPI insulation system; however, after replacing---for economic reasons---the stator winding, another insulation system is used, namely, the Resin Rich system. For correctly making a transition to another insulation system, integrated calculations, including thermal ones, should be carried out. In practice, after changing the insulation system, which may entail certain thermal limitations, it may be necessary to decrease the turbine generator rated power output for its further operation without overheating the stator winding, which can be obtained on the basis of simulation. In this regard, the equivalent thermal conductivity coefficient also plays an important role; its value can be preliminarily analyzed to select the necessary materials in terms of their thermal properties, and their filling factor to retain the turbine generator nominal parameters after its rewinding.

Internal On-line Partial Discharge Analysis of 68.75 MVA Generator Stator Winding Insulation

2016 ◽  
Vol 6 (5) ◽  
pp. 2088 ◽  
Author(s):  
Waluyo Waluyo ◽  
Siti Saodah ◽  
Eltha Hidayatullah
Keyword(s):  
Electric Field ◽  
Partial Discharge ◽  
Surface Discharge ◽  
Damage Effect ◽  
Stator Winding ◽  
Measuring Point ◽  
Temperature Detector ◽  
On Line ◽  
Winding Insulation ◽  
Generator Stator

<p>Partial discharge is a phenomenon of electron ionization occurs due to concentrated electric field in a different edge plane. This phenomenon will be investigated by an electric field measurement in a measuring point. The internal partial discharge will give the insulation damage effect on a generator stator winding due to void existence. This manuscript presents the measurement results of the on-line internal partial discharge on the stator winding insulation of 68.75 MVA generator. It used the resistant temperature detector method and CM2000<sup>TM</sup>. The results were classified into three conditions based on the voids in the generator stator insulation, the internal delamination and the surface discharge.</p>

On-line partial discharge detection of turbine generator using gigahertz-band spatial phase difference method

2000 ◽  
Vol 131 (4) ◽  
pp. 38-43 ◽  
Author(s):  
Masatake Kawada ◽  
Zen-ichiro Kawasaki ◽  
Kenji Matsu-ura ◽  
Satoru Kuroki ◽  
Teruya Osawa ◽  
...  
Keyword(s):  
Phase Difference ◽  
Difference Method ◽  
Partial Discharge ◽  
Turbine Generator ◽  
Spatial Phase ◽  
On Line ◽  
Discharge Detection
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