A generalized approach to partial discharge modeling
01 Aug 1995-IEEE Transactions on Dielectrics and Electrical Insulation (IEEE)-Vol. 2, Iss: 4, pp 510-528
TL;DR: In this paper, a generalized partial discharge (PD) model is proposed to derive approximate relations between defect characteristics, insulation design parameters and test conditions on one side, and measurable PD characteristics on the other.
Abstract: An important tool for improving the reliability of HV insulation systems are partial discharge (PD) measurements. The interpretation of such measurements aims at extracting from the measured data information about insulation defects which then are used for estimating the risk of insulation failure of the equipment. Because the physical understanding of PD has made substantial progress in the last decade, it can now be exploited to support interpretation. In this paper a concept is presented which merges the available physical knowledge about various PD types into a generalized model which can be applied to arbitrary insulation defects. This approach will be restricted to PD of the streamer type in gases and at gas-insulator interfaces which cover a large fraction of the cases encountered in technical insulation systems. The generalized model allows us to derive approximate relations between defect characteristics, insulation design parameters and test conditions on one side, and measurable PD characteristics on the other. The inversion of these relations yields rules for extracting defect information from the PD data. The application of the generalized model is illustrated by two simple examples, namely, spherical voids in an insulator and electrode protrusions in SF/sub 6/. >
Citations
More filters
TL;DR: Different partial discharge detection and measurement procedures suitable for use on cables, capacitors, transformers and rotating machines are examined and compared in this paper, with particular attention given in regard to their suitability to different types of electrical apparatus and cable specimens under test as well as their applicability to discharge site location and their capability to detect different forms of PD.
Abstract: Different partial discharge (PD) detection and measurement procedures suitable for use on cables, capacitors, transformers and rotating machines are examined and compared. Both narrow and wide bandwidth PD detectors are considered; particular attention is given in regard to their suitability to different types of electrical apparatus and cable specimens under test as well as their applicability to discharge site location and their capability to detect different forms of PD. A rather substantial portion of the discussion is devoted to the use of intelligent machines as applied to PD pattern recognition in terms of either PD pulse-height/discharge epoch (phase) distributions or discharge pulse shape attributes.
489 citations
TL;DR: A review of the existing literature on DBDs can be found in this article, where the main part is devoted to the progress on the investigation of different aspects of breakdown and plasma formation with the focus on single filaments or microdischarges.
Abstract: Dielectric Barrier Discharges (DBDs) are plasmas generated in configurations with an insulating (dielectric) material between the electrodes which is responsible for a self-pulsing operation. DBDs are a typical example of nonthermal atmospheric or normal pressure gas discharges. Initially used for the generation of ozone, they have opened up many other fields of application. Therefore DBDs are a relevant tool in current plasma technology as well as an object for fundamental studies. Another motivation for further research is the fact, that so-called partial discharges in insulated high voltage systems are special types of DBDs. The breakdown processes, the formation of structures, and the role of surface processes are currently under investigation. This review is intended to give an update to the already existing literature on DBDs considering the research and development within the last two decades. The main principles and different modes of discharge generation are summarized. A collection of known as well as special electrode configurations and reactor designs will be presented. This shall demonstrate the different and broad possibilities, but also the similarities and common aspects of devices for different fields of applications explored within the last years. The main part is devoted to the progress on the investigation of different aspects of breakdown and plasma formation with the focus on single filaments or microdischarges. This includes a summary of the current knowledge on the electrical characterization of filamentary DBDs. In particular, the recent new insights on the elementary volume and surface memory mechanisms in these discharges will be discussed. An outlook for the forthcoming challenges on research and development will be given. Page 1 of 47 AUTHOR SUBMITTED MANUSCRIPT PSST-101368.R1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 A cc ep e M nu sc rip t Progress on DBD Sources and Filaments 2
473 citations
TL;DR: In this paper, phase averaged plots of the charge distribution over the time (aging plots) and phase resolved histograms (PRPD patterns) at various aging states are presented in order to provide insight into the physical changes in the void during aging.
Abstract: Experimental data are presented of the development of PD activity in artificial air-filled spherical voids in epoxy resin over a period of /spl sim/6 months. The data are presented in the form of phase averaged plots of the charge distribution over the time (aging plots) and phase resolved histograms (PRPD patterns) at various aging states. They are interpreted by comparison to numerical simulations which are based on a physical discharge model. This provides insight into the physical changes in the void during aging. The simulation is the basis for a physically meaningful interpretation of the PD data. It provides rules for the identification of the defect type, the defect quantification, and an assessment of the aging stage. >
344 citations
TL;DR: The goal is to show how much space charge can contribute directly or indirectly, through local electric field magnification or alteration, to increase ageing rate or even trigger more energetic, thus faster, degradation processes in insulation design and electrical apparatus long-term performance/reliability.
Abstract: Considering the title of this paper, one might think that everything has been said, shown, proven and discussed already on ageing and failure of electrical insulating materials, based on at least half century of research work and field feedbacks. However, perhaps there is still room to collect ideas and speculate on apparently proven or brand new concepts, such as the interrelation between ageing mechanisms and physically measurable quantities such as space charge, partial discharges and conduction current. The latter is, indeed, the scope of this paper, which is taken from the Whitehead Memorial Lecture given at the 2010 IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP). On one hand we will revisit the concepts of space charge accumulation in insulating (polymeric) materials, considering also the latest achievements which deal with ultra-fast charge pulses (solitons), on the other hand we will discuss how space charge can contribute to ageing rate under dc, ac or impulsive voltage, directly through electric field alteration, or indirectly modifying a fundamental ageing factor such as partial discharges.The goal is, at the very end, to show how much such basic investigations can have a fundamental impact on insulation design and electrical apparatus long-term performance/ reliability.
234 citations
Cites background from "A generalized approach to partial d..."
...As mentioned above, Eq can modify significantly the field in the void and, consequently, τ affects the discharge activity and particularly the maximum PD amplitude and repetition rate [45]....
[...]
...less than one discharge per second), being determined by conduction charge mobility and charge detrapping at the dielectric-void interface, thus the time between subsequent discharges is long enough to allow a complete relaxation of the space charge by processes such as diffusion into the dielectric bulk, drift along the cavity walls and recombination which have typical time constant of some millisecond [45, 46]....
[...]
TL;DR: In this article, a simulation model for spherical cavities within a homogeneous dielectric material has been developed using finite element analysis (FEA) software in parallel with a mathematical package, which provides many advantages over previous PD models because discharge events can be simulated dynamically and the electric field in the cavity can be calculated numerically.
Abstract: Modeling of the partial discharge (PD) process allows a better understanding of the phenomena. In this paper, a simulation model for spherical cavities within a homogeneous dielectric material has been developed. The model is implemented using Finite Element Analysis (FEA) software in parallel with a mathematical package. This method provides many advantages over previous PD models because discharge events can be simulated dynamically and the electric field in the cavity can be calculated numerically. The model has been used to study the effect of different amplitudes and frequencies of the applied voltage and simulation results have been compared with experimental measurement results. It is found that certain model parameters are dependent on the applied stress and parameters that clearly affect PD activity can be readily identified, these parameters include; the electron detrapping time constant, the cavity surface conductivity, the initial electron generation rate and the extinction voltage. The influence of surface charge decay through conduction along the cavity wall on PD activity has also been studied.
149 citations
Cites background or methods from "A generalized approach to partial d..."
...A previous PD model describing, in detail, the initial electron generation equations, model of streamer process and the estimation of PD charges has been developed to simulate a discharge of streamer type [2]....
[...]
...The detrappable electron effective lifetime τtrap is associated with the surface charge decay rate through charge movement from shallow traps into deeper traps along the cavity surface [2-4]....
[...]
...Einc for streamer type PD depends on the cavity geometry and gas pressure, the dielectric permittivity and the characteristic ionization processes within the gas [2-4]....
[...]
...Charge decay has been considered in several PD models [2, 4]....
[...]
...Surface emission from the cavity wall is the main source of free electrons in a cavity with ongoing PD activity [2, 6]....
[...]
References
More filters
Book•
01 Jan 1992
TL;DR: In this paper, the physical and chemical structure of polymers and their breakdown are discussed, along with the stochastic nature of break-down from empirical and modelling viewpoints, and practical implications and strategies for engineers.
Abstract: The book is in five parts: Part I introduces the physical and chemical structure of polymers and their breakdown; Part II reviews electrical degradation in polymers, and Part III reviews conduction and deterministic breakdown in solids. Part IV discusses the stochastic nature of break-down from empirical and modelling viewpoints, and Part V indicates practical implications and strategies for engineers. Much of the discussion applies to non-crystalline materials generally.
1,177 citations
"A generalized approach to partial d..." refers methods in this paper
...For the modeling of PD in insulating liquids and solids the reader is referred to recent reviews such as [22] and [ 23 ]....
[...]
TL;DR: In this article, the authors present the state of the art of the research on the physics of long sparks and present both the experimental results and the theoretical models which have been obtained for each single phase.
Abstract: The aim of this paper is to present the state of the art of the research on the physics of long sparks. The reference configuration is a non uniform long gap subjected to positive impulse voltages, which is the laboratory schematization of the most critical conditions occurring in the design of EHV apparatus. Under these conditions, the spark formation develops through different subsequent phases : the inception of the first ionization phenomena, the development of corona streamers, the formation of the corona stem and of the leader channel, the leader propagation, the time-evolution of the leader characteristics, the appearance of channel reilluminations, the final jump and the transition to the highly conductive spark channel. Each phase is governed by a complex interaction of electromagnetic, hydrodynamic and thermodynamic elementary processes. Each chapter of the paper presents both the experimental results and the theoretical models which have been obtained for each single phase. In recent years a number of sophisticated measuring systems have been used to study the local conditions of the different discharge phases (space charge distribution, electric field, electron energy, gas temperature and density, etc...) : the first part of each chapter presents a summary of these experimental results, in order to define the physical conditions under which the discharge develops, and to select the elementary phenomena which appear to be dominant. The second part of each chapter presents the different theoretical models, which have been obtained by simplifying the basic electromagnetic, hydrodynamic and thermodynamic equations, according to the dominant phenomena. The good agreement between computed and experimental results, over a large variety of test conditions, certify the large steps forward, which have been taken in the last years by the research on the physics of long sparks. The final objective, i.e. the formulation of a complete breakdown model, able to predict the discharge features in all the possible practical configurations, starting from the physics of the elementary phenomena, is not yet realized, but it appears as a realistic possibility of the further development of the research in this area.
398 citations
TL;DR: In this paper, the authors described the relationship between the induced charge induced on the terminal electrodes of the system and the properties which are usually measured by applying it to a spheroidal void located in a simple disk-type spacer.
Abstract: Transients associated with partial discharges in voids can be described in terms of the charges induced on the terminal electrodes of the system. The relationship between the induced charge and the properties which are usually measured is discussed. The method is illustrated by applying it to a spheroidal void located in a simple disk-type spacer. >
265 citations
"A generalized approach to partial d..." refers background or methods in this paper
...A plot of K(a/b) and a detailed discussion are given in [ 21 ]....
[...]
...The only defect type for which this problem has been treated hitherto are ellipsoidal voids in a dielectric having the axis of rotation parallel to the electric background field E, [ 21 ,33,40]....
[...]
...A further group of publications provided the basis for relating the physical processes to measurable PD signals [ 21 ]....
[...]
...According to Equation (19) in [ 21 ], the induced charge q’ associated with a field change AE in an ellipsoidal void is...
[...]
...As pointed out in detail in [ 21 ] the field A, is obtained by solving the Laplace equation for the defect free insulation system with the boundary conditions A, = 1 at the measuring electrode and A, = 0 at all other electrodes....
[...]
TL;DR: In this article, a survey of the current state of understanding of leader breakdown of electronegative gases in nonuniform field gaps and under fast-rising voltage waveforms is given.
Abstract: A survey is given of the present state of understanding of leader breakdown of electronegative gases in nonuniform field gaps and under fast-rising voltage waveforms. The basic physical processes involved are the formation of a pulsed streamer corona, the transformation of one of the streamers into a leader step, the temporal development of the leader channel, and the stepped propagation of the leader through the gap. The growth and structural characteristics of the corona are modeled and the results obtained are used to derive simple approximations for the spatial corona extension and the corona charge. Two leader inception mechanisms are discussed, namely, the stem and the precursor mechanisms. Inception criteria and characteristic time scales are derived for both of them in terms of the experimental parameters. A simplified model, which also predicts the random aspects of leader propagation through the gap, is presented. Some typical gas-insulation design problems are treated as examples. >
172 citations