3D Simulation of Partial Discharge in High Voltage Power Networks

Open accessPartial discharge (PD) events arise inside power cables due to defects of cable’s insulation material, characterized by a lower electrical breakdown strength than the surrounding dielectric material. These electrical discharges cause signals to propagate along the cable, manifesting as noise phenomena. More significantly, they contribute to insulation degradation and can produce a disruptive effect with a consequent interruption of power network operation. PD events are, therefore, one of the best ‘early warning’ indicators of insulation degradation and, for this reason, the modeling and studying of such phenomena, together with the development of on-line PDs location methods, are important topics for network integrity assessment, and to define methods to improve the power networks’ Electricity Security. This paper presents a 3D model of PD events inside a void in epoxy-resin insulation cables for High Voltage (HV) power networks. The 3D model has been developed using the High Frequency (HF) Solver of CST Studio Suite® software. PD events of a few µs duration have been modelled and analyzed. The PD behavior has been investigated using varying electrical stress. A first study of the PD signal propagation in a power network is described

A new method to localize partial discharges on power cables using time reversal and TLM numerical method – A review

The file attached to this record is the author's final peer reviewed version.Insulation deterioration is often caused by partial discharge (PD) events. The adoption of on-line PD location methods is one of the most suitable methods to perform the power networks condition monitoring to improve their resilience and to guarantee electricity supply security. This paper reviews the results obtained in the design process of a new on-line PD location method based on the use of the electromagnetic time reversal (EMTR) theory and the Transmission Line Matrix (TLM) numerical method. Building on the work previously presented at the IWCS, where the method had been presented using two observation points, this paper shows further progress in this research and as a proof of its effectiveness, shows its ability in locating PDs using only one observation point. The procedure of the method is briefly described and its performance that overcomes the shortcomings of the traditional PD location methods are summarized. Finally, future related activities are described

Time Reversal for Partial Discharge Localization on Power Lines with Different Termination Impedances

This paper describes a new method for the on-line location of partial discharges (PDs) in power transmission and distribution networks based on Electromagnetic Time Reversal (EMTR) theory and on the Transmission Line Matrix (TLM) method in order to describe the time reversed propagation. In particular, the paper shows the effectiveness of the method in localizing the PD source when the impedances at the terminations of the line are unknown and describes the procedure to be followed in this case. The analysis is performed in simulation, and a model of the PD signal propagation that is able to reproduce the distortion phenomenon that affect the PD signal propagation on power lines and thus the accuracy of the on-line PD location methods is also described

Electromagnetic Beam Position Monitoring Model for Particle Energy Linear Accelerator

Beam Position Monitoring (BPM) systems are crucial in particle acceleration facilities such as linear and circular accelerators. They are used to maintain a stable and precise beam position to achieve a high level of beam quality. BPMs are also essential for accelerator commissioning, performance optimisation, and fault analysis. Beam functional properties information, such as displacement from the desired axis, information about synchrotron oscillations and betatron movements can be derived from data gathered in BPM systems. Medical linear accelerators (linacs) also employ BPM measurements to ensure optimal generation of treatment radiation. The most common form of analysis is to use a multi-physics based approach and model the beam as a stream of electrons, often involving Monte Carlo implementation – an accurate but computationally expensive approach. This paper presents a simple, but robust and efficient, CST microwave model of the linear accelerator (linac) beam, generated using a simplified approach to beam modeling that uses a conducting filament in place of the particle. This approach is validated by comparison with published work. An approach to BPM using the method applied in this paper opens up opportunities to further analyze the overall design and that of components of particle accelerator systems using commonly available full-wave electromagnetic simulators without the need to include specific particle solutions

Application to Real Power Networks of a Method to Locate Partial Discharges Based on Electromagnetic Time Reversal

This work was supported by the European Union’s Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie Grant under Agreement 838681.The paper presents an experimental validation of a method to locate partial discharges (PDs) on power distribution and transmission networks. The method is based on electromagnetic time reversal (EMTR) theory, and it uses a Transmission Line Matrix (TLM) model to describe the propagation of the PD signals in the reversed time. Since PDs are regarded as a symptom of insulation degradation, on-line PD location is considered an important approach to monitoring the integrity of a power distribution network, with the aim of detecting and preventing faults and improving network reliability. In this paper, the EMTR-based method is described and its effectiveness in PD localization using only one measurement point is demonstrated in three real 33 kV power lines. Its effectiveness is proved with and without an on-line electromagnetically noisy environment, and its accuracy is evaluated with respect to different signal-to-noise ratio (SNR) levels of the networks. The validation shows that the method is able to locate PDs with an error of 0.14% with respect to the total length of the line in the absence of noise, and with an error that is always lower than 0.5% for an SNR down to -7 dB

Comparison of Data with Multiple Degrees of Freedom Utilizing the Feature Selective Validation (FSV) Method

This research is the product of a collaboration between: 1. Harbin Institute of Technology, China 2. De Montfort University, UK 3. University of L'Aquila, Italy “© 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksThe feature selective validation method has been shown to provide results that are in broad agreement with the visual assessment of a group of engineers for line, 1-D, data. An implementation using 2-D Fourier transforms and derivatives have been available for some years, but verification of the performance has been difficult to obtain. Further, that approach does not naturally scale well for 3-D and higher degrees of freedom, particularly if there are sizable differences in the number of points in the different directions. This paper describes an approach based on repeated 1-D FSV analyses that overcomes those challenges. The ability of the 2-D case to mirror user perceptions is demonstrated using the LIVE database. Its extension to n-dimensions is also described and includes a suggestion for weighting the algorithm based on the number of data points in a given “direction.

Down-sampled and Under-sampled Data sets in Feature Selective Validation (FSV)

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Feature Selective Validation (FSV) is a heuristic method for quantifying the (dis)similarity of two data sets. The computational burden of obtaining the FSV values might be unnecessarily high if data sets with large numbers of points are used. While this may not be an important issue per se it is an important issue for future developments in FSV such as real-time processing or where multi-dimensional FSV is needed. Coupled with the issue of data set size, is the issue of data sets having ‘missing’ values. This may come about because of a practical difficulty or because of noise or other confounding factors making some data points unreliable. These issues relate to the question “what is the effect on FSV quantification of reducing or removing data points from a comparison – i.e. down- or under-sampling data?” This paper uses three strategies to achieve this from known data sets. This paper demonstrates, through a representative sample of 16 pairs of data sets, that FSV is robust to changes providing a minimum data set size of approximately 200 points is maintained. It is robust also for up to approximately 10% ‘missing’ data, providing this does not result in a continuous region of missed data

Measuring the shielding properties of flexible or rigid enclosures for portable electronics

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Heaviside, in volume 1 of Electromagnetic theory, considered shielding of conducting materials in the form of attenuation. This treatment is still significant in the understanding of shielding effectiveness. He also considered propagation of electromagnetic waves in free-space. What Heaviside (1850–1925) could never have imagined is that 125 years later, there would be devices we know as mobile phones (or cell phones, handies, etc.) with capabilities beyond the dreams of the great science fiction writers of the day like H. G. Wells (1866–1949) or Jules Verne (1828–1905). More than this, that there would be a need for law enforcement agencies, among others, to use electromagnetically shielded enclosures to protect electronic equipment from communicating with the ‘outside world’. Nevertheless, Heaviside’s work is still fundamental to the developments discussed here. This paper provides a review of Heaviside’s view of shielding and propagation provided in volume 1 of Electromagnetic theory and develops that to the design of new experiments to test the shielding of these portable enclosures in a mode-stirred reverberation chamber, a test environment that relies entirely on reflections from conducting surfaces for its operation