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Transcript of PD Presentation
Q resolution = 100 2x2 3x3 4x4 20x20 Time = 6.6198 s Comparing Resolutions PD Definition A localized electrical discharge that only partially bridges the insulation between conductors and which may or may not occur adjacent to a conductor. Types of PD Reason for Identification φ-q-n Analysis Corona Surface Floating Void/Internal φ - Phase q - Charge magnitude n - number of pulses (resolution) Time = 12.9236 s Time = 7.1004 s Time = 52.1807 s Time = 96.3315 s Time = 23718 s = 6.59 hrs IEC 60270: φ-q-n Analysis Applicability:
PD Initiation and Breakdown
Deterioration due to old age
Premature aging due to thermal stressing
Poor design and manufacturing methods
Bad workmanship (Cable joints and termination which are made onsite) Bibliography Y. Tian et al "Comparison of On-line Partial Discharge Detection Methods for HV Cable Joints"
J. Hunter "Title"
D. J. Swaffield et al "Characterisation of surface partial discharge behaviour in liquid nitrogen"
R. Patsch and D. Benzerouk "Characterization of Partial Discharge Processes - what Parameters work best?"
G. Chen et al "Comparison between Optical and Electrical Methods for Partial Discharge Measurement"
L. Hao et al "Identification of Multiple Partial Discharge Sources"
D. J. Swaffield et al "Partial Discharge Characterization of Streamers in Liquid Nitrogen under Applied AC Voltages
Group Phases and Magnitudes Contents Any Questions? Thank you for watching L. Hao et al "Partial Discharge Source Characterization within a HV Cable Joint
L. Hao and P. L. Lewin "Partial Discharge Source Discrimination using a Support Vector Machine"
S. S. Kumar "PD data analysis and evaluation of partial discharge patterns for uniform characterisation"
S. Das and P. Purkait "Phi-q-n Pattern Analysis for Understanding Partial Discharge Phenomena in Narrow Voids" PD definition & types
PD Initiation and Breakdown
Identification methods & tools
MATLAB program explanation
Demonstration and Black
Box Test D. J. Swaffield et al "Characterisation of surface partial discharge behaviour in liquid nitrogen" Shape of plot not significantly effected by small frequency inaccuracies Local field only part determined by voltage so phase angle has only limited relevance - historically most frequently used parameter Just describe specific data set but do not reveal information about local physical processes Time = 22.7884 s Large Number of grouped pulses
Occurs in negative half cycle Source: F.H. Kreuger, "Recognition of Discharges" Partial Discharge (PD)
Identification Sam Boleat
Abdinuur Guushaa Detection Methods Radio Frequency Current Transducer
Acoustic Y. Tian et al "Comparison of On-line Partial Discharge Detection Methods for HV Cable Joints" Indentification
Tools φ-q-n Analysis Pulse Sequence Analysis (PSA) Support Vector Machines (SVM) PD propagates and develops into electric trees
Insulation fails completely
Breakdown to earth or between two phases
Some relatively benign (corona)
Others more dangerous (discharge within cable or accessories)
Assessment of service life
Assessment of design/ type testing
Discriminate PD sources
Overall: Reduce Outages, Schedule Maintenance and reduces cost of running network Simple to analyse if only one source of PD Easy to design and implement Quick Result Analysis Useful for human identification when only one PD source exists High Charge Magnitude
Occurs in 1st an 3rd quadrant of cycle More pulses at lower magnitude
Occurs in 1st and 3rd quadrant of cycle Find Max Peak Delete Peak and Find Next Max Add Q and Phi value to Matrix Original Data Modulated and Noise Removal Source: F.H. Kreuger, "Recognition of Discharges".
Source: Electra . Modulated Corona Surface Void IEC 60270 High-Voltage Test Techniques - Partial Discharge Measurements (Artificial PD Sources Diagrams) Bounded Void Defining Characteristics
Density Source: L. Hao et al "Identification of multiple Partial Discharge Sources" Source: L. Hao et al "Identification of multiple Partial Discharge Sources" Source: L. Hao & P. L. Lewin "Partial Discharge Source Discrimination using a Support Vector Machine" PD Identification UnBounded Void Corona Contact Floating Surface Discharge Pattern Comparison:
Method of Implementation: PSA can reveal information about the local processes PSA can detect changes in pulse width φ-q-n Analysis SVM is identifcation tool and not analysis SVM effectiveness determined by feature vectors Use computation tool to manipulate raw data to produce 3D graph