Search results for "Discharge"

Characteristics of partial discharges in an experimental setup reproducing HVDC cable insulation operating conditions

2021

The occurrence of Partial Discharge (PD) inside a cavity subjected to HVDC voltage can be considered as one of the most likely sources of insulation ageing and failure. In practical applications, the recognition of PD under HVDC is more difficult than under AC stress because of the lower repetition rates and the impossibility to obtain a PD pattern synchronized with the waveform of the applied voltage. In this paper, the relationship between conduction phenomena in dielectrics and the occurrence of PD is investigated by means of a novel experimental setup. A couple of dielectric cells connected in series is subjected to various HVDC stress levels. The applied voltage is divided between the …

Investigation of PCB-based Inductive Sensors Orientation for Corona Partial Discharge Detection

2022

This paper presents an experimental investigation of two different printed circuit board (PCB) inductive sensors, with meander and non-spiral shapes, to assess their capabilities and best orientation for corona partial discharge (PD) detection. First, simulations with the Ansys HFSS software are performed in order to evaluate the equivalent electrical circuit of the two sensors and their 2d radiation patterns. The meander sensors presented a resonant frequency of 600 MHz, while it was around 1.1 GHz for the non-spiral. The 2d radiation pattern showed that better sensitivity is achieved when the inductive sensor is oriented 90 degrees with respect to the PD source. Experimental tests showed …

CARATTERIZZAZIONE ELETTROMAGNETICA DI IGBT IN PRESENZA DI SCARICHE PARZIALI

2014

Use of Time-Frequency map combined with DBSCAN algorithm for separation of partial discharge pulses under DC voltage

2022

The Phase-Resolved-Partial-Discharge pattern (PRPD) is a conventional technique used for the evaluation of partial discharges (PD) phenomena in High-Voltage-Alternating-Current (HVAC) systems. This map is constructed by plotting the peak of each detected pulses as a function of the phase angle of the supply voltage. Therefore it is obvious that this technique cannot be used for the analysis of data from PD mesaurement under different supply voltage condition (DC). The aim of this paper is to evaluate the application of the Time-Frequency map (TF map) for the analysis of a dataset obtained from PD measurement under DC voltage. A density-based clustering algorithm was also used to gain more i…

On PD mechanisms at high temperature in voids included in an epoxy resin

2001

In this paper the effects of temperature on partial discharge (PD) activity taking place inside a spherical void in epoxy resin system are studied. Indeed, some experimental tests previously performed on specimens, having different void shapes, under multi-stress condition of temperature and voltage, have shown very different PD amplitude distributions at temperatures higher than ambient. However, this phenomenon cannot be explained only by taking into account the different thermobaric conditions of the enclosed gas. In consequence of the general physical inaccessibility of such voids, a study is here performed using a numerical model based on an evolutionary optimization algorithm. This is…

A combined CWT-DWT method using model-based design simulator for partial discharges online detection

2009

The suppression of noises is fundamental in onsite Partial Discharge (PD) measurements. For this purpose, the wavelet transform analysis method has been developed and it is a powerful tool for processing the transient and suddenly changing signals. As the wavelet transform possesses the properties of multi-scale analysis and time-frequency domain localization, it is also particularly suitable to process the suddenly changing signals of the partial discharge pulse (PD). In this paper, an improved Wavelet denoising method developed by a model-based design software is presented. Simulations are provided as well as some results obtained during laboratory experiment and on-line PD measurements. …

UN METODO COMBINATO CWT-DWT PER IL RICONOSCIMENTO DI SEGNALI DI SCARICHE PARZIALI

2010

DESIGN OF A FAULT AND PARTIAL DISCHARGES LOCATION DEVICE FOR CABLE POWER NETWORK

In this thesis, a digital device for fault and on line partial discharge location is presented. The device employs the traveling wave method for two or multiple ends. The designed prototype shows interesting features connected to the low cost and to the possibility to collect data from different locations thus providing additional functionalities deriving from pre-fault and data analysis, relating the existence of defects to the subsequent fault event. The device also enables the acquisition of the temperature on the cable section where the sensor is installed. Such installation can also support DSO and TSO for carrying out both on-event and condition based maintenance, discovering the caus…

WIRELESS DETECTION OF PD PATTERNS: APPLICATIONS IN SMART GRIDS AND MODERN POWER SYSTEMS

In this thesis, different challenges for various applications of a wireless PD detection instrument are discussed and relevant solutions are proposed. The main purpose is to assess the applicability of such technology both in current HV and MV power systems as well as in future applications for smart grids. The main challenges for these types of diagnostic systems are the following: • voltage synchronization of Phase Resolved PD pattern; • PD recognition under non-sinusoidal voltage waveforms; • PD recognition under sinusoidal voltage superimposed harmonics; • PD recognition in laboratory and in real world situations under noise and other source of disturbance. Thanks to the collaboration w…

Generalised stage-discharge relationship for rectangular weirs

2018

Rectangular weirs, which are very common hydraulic structures used in irrigation channels as water measuring devices, can be used for measuring very small discharges as well as high flow rates. From the practical point of view the availability of a unique stage-discharge formula that can be applied for the different types of the rectangular weirs would be of great practical importance. At first, in this paper the Buckingham’s Theorem of the dimensional analysis and the self-similarity theory are used to deduce the stage-discharge curve of different kinds of rectangular weirs such as slit and partially contracted ones. Then the proposed formula is calibrated using both the experimental data …