Partial discharge simulations used for the design of a non-intrusive cable condition monitoring technique (original) (raw)
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Condition Monitoring of Medium Voltage Electrical Cables by Means of Partial Discharge Measurements
SAIEE Africa Research Journal, 2014
The purpose of this paper is to discuss condition monitoring (CM) of medium voltage electrical cables by means of partial discharge (PD) measurements. Electrical cables are exposed to a variety of operational and environmental stressors. The stressors will lead to the degradation of the cable's insulation material and ultimately to cable failure. The premature failure of cables can cause blackouts and will have a significant effect on the safety of such a network. It is therefore crucial to constantly monitor the condition of electrical cables. The first part of this paper is focussed on fundamental theory concepts regarding CM of electrical cables as well as PD. The derivation of mathematical models for the simulation of PD is also discussed. The simulation of discharge activity is due to a single void within the insulation material of medium voltage cross-linked polyethylene (XLPE) cables. The simulations were performed in the MATLAB ® Simulink ® environment, in order to investigate the effects of a variety of parameters on the characteristics of the PD signal. A nonintrusive CM technique was designed for the detection of PD activity within cables. The CM technique was used to measure and analyse practical PD data. Two MATLAB ® programs were designed to analyse the PD data in both the time-domain and frequency-domain.
European Transactions on Electrical Power, 2007
Based on experimental investigations a theoretical model of a sensor f o r partial discharge (P D) detection on high-voltage cross-linked polyethylene (XLPE)-insulated cables respectively joints has been developed. The model handles radial symmetric sensors and is based on the Finite-Difference Time-Domain (FDTD) method in which a cylindrical coordinate system is exploited. The calculation providesfield values at each node of the FDTD grid. The field pattern in the cable and sensor at different time steps is used to investigate the coupling mechanism of the sensor. It is also used f o r parametric studies of the sensoc e. g. the dependence of the sensitivity on geometrical characteristics of the senso< which is investigated theoretically as well as experimentally. Results of computer simulation are in a good agreement with experimental data derived f o r such sensors.
Solid Dielectrics (ICSD), 2013 IEEE International Conference on, 2013
In high voltage power cable, partial discharge (PD) phenomenon may occur within defects that exist in its insulation system. The insulation is normally made of a dielectric material, typically polymeric materials. Repetition of PD activity at the defect site may cause insulation breakdown when the defect grows until it bridges the electrodes between the insulation. Consequently, breakdown of the whole cable will occur. Thus, measurement of PD activity within cable insulation system has been extensively used to monitor the condition of power cables in service. A void cavity is one of the most common PD sources when a cable insulation is stressed under high electric field. In this work, measurements of PD activity within an artificial cylindrical void in the insulation layer of a 22 kV cross-linked polyethylene (XLPE) cable was performed. A two-dimensional model of a cable insulation geometry with a void was also developed using finite element analysis (FEA) software. The model was used to calculate the electric field magnitude in the void within the cable insulation under different conditions of voids and insulation. From this work, an understanding on PD phenomenon within a cylindrical void in a power cable insulation can be enhanced.
On-line Partial Discharge Detection in Cables - 1997
This paper describes a11 on-line partial discharge (PD) detection technique in power cables. The technique uses a digital spectrum anal?/zer with a high-frequency preampl(fier and several types of highfrequency inductive sensors. In extruded and inipregnated power cables, the PD detection IS nrade in the VHF range. The suitability and the sensitivity of the VfIF technique were checked agoinst two other conventionnl PD detecting methods (Pulse Phase Annlyzer and Fast Digital Scope) by performing PD n~ea.surenrents i n EPR-insulated cable under laboratory-coiitrollerl concli tioiis. The sui to b i li ty an cl semci tivi ty of the VHkmethod were as good CIS the two conventionnl PD de te cti 011 171 e th o CIS. The VHF method then wns u.secl to conduct on-.cite PD nrea.surenrent.s in se\)eral power cables. These nreasurements were conclucted while the cables were in .service. Special care wns given to distinguish between external electroningnetic noise and electronragnetic signals produced by the PD activities inside the cnhle insulation.
Partial Discharge Measurement and Monitoring on High Voltage XLPE Cables
To check production quality, partial discharge (PD) measurements are performed on underground cables or cable drums. PD impulses propagate through the cable and are reflected at the ends and on joints. By measuring the delay between the impulse which is directly coming into the PD instrument and the impulse which is reflected at the end, a location of the PD source can be done. Due to reflections, partial discharges generally occur as pulse groups, which can lead to superimposed oscillations of the PD filter which is required to determine the charge value as per IEC 60270. With a new approach of simultaneous measurement at different receiver frequencies the superposition effects can be eliminated. With PD monitoring the reliability and availability of the equipment will increase and the life time of the cable lines will be extended. Other important benefits of monitoring are higher safety for the personnel and reduced environmental risks. In the paper recommendations are given for t...
Investigation of PD detection on XLPE cables
The insulation lifetime of XLPE power cables is determined by several factors. One of the most important of these is the occurrence of partial discharge (PD) in the dielectric. The ability to detect and locate the PD sources is limited by attenuation and distortion of the high frequency PD pulses as they propagate through the cable. This paper presents the results of measurements of PD pulses that are generated by an artificial PD defect with capacitance-coupled sensors used for the detection of PD, rather than a high frequency current transformer (HFCT). The results show that the external capacitance sensors have a number of advantages, such as better sensitivity, for the detection of PD pulses. PD pulse waveforms were evaluated by three different integral methods in order to estimate the best way to characterise the PD pulses. The PD pulse is severely attenuated and distorted with increasing length of the power cable and the frequency of the PD pulse and some means of characterising is necessary. Simulation results are compared with test measurement results and it has been found that the cable model developed and used was able to predict the measurement results accurately.
Development process and testing of partial discharge detection device on medium voltage XLPE cable
Indonesian Journal of Electrical Engineering and Computer Science
High voltage assets play a vital role in providing uninterrupted power to the consumers and any slight problems experienced by the assets may cause losses in millions of dollars to businesses. Therefore it is of utmost importance to monitor the health of high voltage assets. This research presents the development process of a Partial Discharge (PD) device that is able to detect PD acoustic waves for monitoring high voltage assets purposes. Medium voltage Cross-Linked Polyethylene (XLPE) cable was used which was introduced with spherical void defects at the joints of the cable that functioned to produce PD acoustic waves. Outcome of the development processes provides the finished design of the PD sensing device, known as Partial Discharge Detection (PDD) device. The functionality of the PDD device was also assessed through controlled experimentations, and they proved to be successful. Pure PD waveform captured by the ultrasonic sensor was similar when compared to a HFCT sensor’s pure...
Partial Discharges Classification Methods in XLPE Cable: A Review
IEEE Access
Partial discharge (PD) signal classification analysis on cross-linked polyethylene (XLPE) cables is complex, requiring a comprehensive understanding of the characteristics of PD patterns. In the realm of high-voltage electrical insulation, PD pattern characteristics, such as PD charge and inception voltage, are essential as assessment criteria in diagnostics systems using PD classifiers. This paper provides a review of various PD patterns and classifiers used by previous researchers, specifically for XLPE cables. In addition, the differences of the research on various sensor development based on PD detection in the past 27 years are also discussed. The repeatability, recognition accuracy, recognition speed, and effect of feature sizes on each PD classification method are reviewed and explained. The review indicates that the pattern recognition for PD signal using artificial neural network (ANN) exhibits better performance in terms of accuracy and repeatability than the other methods, and the reduction of feature size does not affect the accuracy of ANN. INDEX TERMS Partial discharge (PD), cross-linked polyethylene (XLPE) cable, solid insulator, pattern recognition, feature extraction, artificial neural network (ANN)
Time domain analysis of partial discharges envelope in medium voltage XLPE cables
Electric Power Systems Research, 2015
Partial discharge (PD) analysis has been widely used to detect premature degradation of power cables. Although there are recognized techniques for PD analysis, there is still lack of knowledge about measuring and modeling this phenomenon. This paper proposes a new model based on time domain parameters of the PD signal envelope. The proposed variables (time duration, and rising and falling slopes of the envelopes), together with conventional PD analyses focused on PD amplitude and phase resolved patterns, will provide a better understanding of this phenomenon. Based on this model, a new technique to reshape the PD signal envelope is also proposed that compensates the negative effect of dispersion in the location techniques that estimate the time of arrival (TOA). Experimental results were obtained in the lab, where a power cable has been artificially damaged in order to produce PD. To this end, a specific PD on-line acquisition system has been developed. In the first set of experiments, we illustrate how the cable attenuates and disperses the PD signal envelope. In the second one, we show how the proposed variables are useful to distinguish among different types of PD sources. Finally, an accurate estimation of the PD source location is achieved by measuring the time of arrival of the PD signal envelopes at both cable ends, and reshaping one of the signal captured. This technique improves the accuracy of the estimated location of the PD sources, both in simulation and in experimental results.
Partial discharge detection by using combined VHF and AE sensors in XLPE power cables
2019
The purpose of this article is to troubleshoot and detection a partial discharge in cross-linked polyethylene (XLPE) cable by combining two very-high-frequency (VHF) and acoustic emission (AE) sensors, which is a novel approach to troubleshooting. The small size of these signals is the main problem in partial discharge (PD) measurements, which might cause the signal mix completely with noise and make troubleshooting difficult. Hence, attention has been paid to high bandwidth to eliminate disturbing noise. In this paper, Rogowski's coil is designed as a kind of VHF sensor for troubleshooting purposes. Then, it simulates and examines the characteristics of the partial discharge in the power cables that have been occurred due to the existence of a cavity. In the end, in order to prove the efficiency of the intended method, the actual partial discharge test was performed using the VHF and AE sensors. The combination of two VHF and AE sensors is capable of eliminating electrical inte...