Partial discharge detection and localization along medium voltage cables

In the last years different partial discharge (PD) measuring techniques have been developed because PD diagnostic is the most widely tool to evaluate the insulation condition of a power cable. Recently non-conventional methods and sensors have been used in order to reach improved results in PD measurements. The purpose of this work is to perform measurements that allow to study the variation of pulses when they travel along a MV cable and to locate the pulse source through the time arrival difference of the pulses obtained from two sensors installed separately.

Partial Discharge on-line measures in cable's EPR insulation

In this paper, an experimental study, carried out on an operating MV cable, is presented. The aim is to identify, locate and characterize defects in the cable's EPR (ethylene-propylene copolymer rubber) insulation. Direct partial discharge measurements have been compared to those obtained by high frequency electromagnetic field measures. The latter have been carried out using a sensor which does not require any galvanic connection with the system under test and that performs an intrinsic localization of the defect. Moreover, an analysis of an MV cable junction has been carried out using the same tools.

A two-end traveling wave fault location system for MV cables based on LoRa technology

In this paper a new low cost device is proposed for fault location in power distribution system. The device is part of a system that should include several units installed in couples at the two ends of MV cable lines. Their low cost justifies a widespread installation of these devices, moreover other functionalities could be considered so as to enrich the potential of the system for MV cables monitoring and asset management. The system exploits a two-end traveling wave technique, low complexity and low cost solutions both for the analog front end as well as for the communication infrastructure. A LoRa network is indeed considered as wireless modulation technique perfectly suited when commun…

Tecniche di riconfigurazione di sistemi fotovoltaici parzialmente oscurati per la massimizzazione della produzione di energia elettrica

Modello per la simulazione di scariche parziali con approccio probabilistico

Un nuovo approccio per l’identificazione di segnali di scariche parziali multi sorgente attraverso decomposizione wavelet multirisoluzione

D2SI – Device for the Diagnosis of Insulation Systems

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

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 New Approach to Partial Discharge Detection Under DC Voltage: Application to Different Materials

Usability of a new Direct Current Periodic waveform for partial discharge qualification in HVDC systems is exemplified by tests performed on different materials.

Caratterizzazione di dielettrici solidi nanostrutturati mediante invecchiamento combinato in presenza di scariche parziali e temperatura

Optimization of photovoltaic energy production through an efficient switching matrix

This work presents a preliminary study on the implementation of a new system for power output maximization of photovoltaic generators under non-homogeneous conditions. The study evaluates the performance of an efficient switching matrix and the relevant automatic reconfiguration control algorithms. The switching matrix is installed between the PV generator and the inverter, allowing a large number of possible module configurations. PV generator, switching matrix and the intelligent controller have been simulated in Simulink. The proposed reconfiguration system improved the energy extracted by the PV generator under non-uniform solar irradiation conditions. Short calculation times of the pro…

Time Evolution of Partial Discharges in a Dielectric Subjected to the DC Periodic Voltage

Partial discharge (PD) detection can be considered one of the most useful tools for assessing the insulation conditions of the power apparatus in high-voltage systems. Under AC conditions, this analysis is widely employed in online and offline tests, such as type tests or commissioning, and can be carried out by applying the phase-resolved PD (PRPD) method, since the patterns can give information about the defect classification. Under DC voltages, the classic pattern recognition method cannot be performed, and the measurements show complexities related to the nature of the phenomena. For this reason, to date, a standard for PD measurements under DC does not exist. In previous papers, a new …

Dispositivo portatile per la rilevazione di scariche parziali

A Comparison of Special Bonding Techniques for Transmission and Distribution Cables under Normal and Fault Conditions

In this article, a review of the existing special bonding techniques for medium voltage and high-voltage cables is presented. Special bonding techniques have the purpose of reducing sheath currents, thereby limiting copper losses and the reduction of the ampacity of cables. The literature review shows various bonding techniques and how these have evolved over the years thanks to new technologies. Simulations of each technique are performed in MATLAB/Simulink, to compare their strengths and drawbacks both under normal conditions and in the presence of a single-line-to-ground fault.

A new approach to calibrate the thermal conditions in space charge measurements on HVDC mini-cables

The PEA method is currently widespread used for space charge measurements in mini-cables in order to qualify the behavior of semicon-dielectric-semicon compound under electric and thermal stress. The main goal of this research is to quantitatively evaluate the relationship between the thermal boundary conditions applied to cables or mini-cables and the maximum local electric field due to the accumulated space charge. Hitherto, several research groups have obtained thermal gradients over the dielectric's radius heating the conductor by Joule effect due to an induced current. In this paper, a numerical approach is offered to calibrate the heat exchange boundary conditions to apply to a sample…

Processo di denoising per l'acquisizione di segnali di scariche parziali mediante trasformata wavelet discreta (DWT)

Tecniche di ottimizzazione delle connessioni di pannelli solari

Applicazione della decomposizione wavelet multirisoluzione (MWD) per il riconoscimento di segnali di scariche parziali multisorgente

A Model for Assessing the Magnitude and Distribution of Sheath Currents in Medium and High-Voltage Cable Lines

In this article, the authors discuss a simulation model to study the effect of cross-bonding of metallic sheaths, and/or nonmagnetic armors, of single-core medium- and high-voltage cables in the same circuit. In single-core cables, the resistive losses due to the induced circulating currents in cable sheaths or armors cause an increase of the cable temperature, which therefore reduces its ampacity. This is a serious issue affecting the distribution and transmission lines. In addition, the risk of electric shock due to induced voltages may be present if a person is in contact with the armor/sheath at its unbounded end. For these reasons, special bonding techniques of metal sheaths are employ…

Electromagnetic radiated field measurements for partial discharge diagnostic

Recently, improvements have been made in the diagnostic of electrical insulation systems by means of electric Partial Discharge (PD) standard measurements through a stochastic approach in the treatment of the acquired data: in this way, the identification of the defects as well as the separation of multiple defects simultaneously active, have been successfully performed. However, the standard PD measurement process can be affected by the well-known parasitic effects due to conducted noise whose spectrum can have characteristics similar to those of the measured signal. Moreover, the classic PD measurement system have to be suitable assembled on the Device Under Test (DUT) so determining a co…

Un modello per l’analisi dei disturbi di modo comune indotti su azionamenti in presenza di fulminazione atmosferica

Polarity reversal in HVDC joints - The effect of the axial thermal conduction

It has been shown that the establishment of a thermal gradient over the radius of HVDC cables involves the accumulation of space charge within the dielectric layer. High thermal gradients over the insulation thickness of loaded cables can lead to the inversion of the radial electric field pattern. In this scenarios, transient overvoltages and polarity reversal can lead to local and transitory peaks of electric field. Since the temperature distribution plays an important role in reaching critical values of the electric field, it has been considered interesting to have a more in-depth view of the thermal behavior of HVDC systems close the discontinuities of the geometry along the cable axis. …

Diagnosi dell’affidabilità dei sistemi di isolamento mediante l’impiego di sonde di campo elettrico e magnetico per la misura di scariche parziali

Different Space Charge Behavior of Materials Used in AC and DC Systems

The aim of the present work is to evaluate the behavior, from the space charge accumulation phenomenon point of view, of three different XLPE specimens used as insulation materials in high voltage systems. Considering that under DC stress the charge accumulation is more relevant as compared to the AC case, in the specimens for DC applications additives are typically added. In this work, three different specimens are analyzed. One is a free additive sample used conventionally under AC stress and two others include different additives that are used under DC stress. In order to measure the space charge accumulation, the Pulsed Electro Acoustic (PEA) method has been employed. For each sample, t…

Investigation on partial discharges in HVDC cables after polarity reversal events

Due to the accumulation of space charge inside the insulating layer of HVDC cables, the electric field under load conditions may be altered compared to what is established in HVAC cables. For example, a high thermal gradient leads to the inversion of the electric field pattern until the maximum value is reached in proximity of the dielectric-semicon interfaces. These maximum values can be further increased due to transient overvoltages and polarity reversal events until reaching electric field values higher than the rated ones. The main goal of this research is to investigate the possibility that, during these transient phenomena, conditions are created that favor the occurrence of partial …

Diagnosi e valutazione dell'affidabilità di sistemi di isolamento di componenti di impianti attraverso l'applicazione di tecniche di intelligenza artificiale alla misura di scariche parziali

Partial Discharges analysis and parameters identification by continuous Ant Colony Optimization

The technique of ant colony optimization has been employed in this paper to efficiently deal with the problem of parameters identification in partial discharge, PD, analysis. The latter is a continuous optimization problem. From the technical point of view the identification of these parameters allows the modeling of the phenomenon of Partial Discharges in dielectrics. In this way it is possible the early diagnosis of defects in Medium Voltage cable lines and components and thus it is possible to prevent possible outages and service interruptions. Analytically, the problem consists of finding the Weibull parameters of the Pulse Amplitude Distribution (PAD) distributions allowing the identif…

Composite laminates buckling optimization through Levy based Ant Colony Optimization

In this paper, the authors propose the use of the Levy probability distribution as leading mechanism for solutions differentiation in an efficient and bio-inspired optimization algorithm, ant colony optimization in continuous domains, ACOR. In the classical ACOR, new solutions are constructed starting from one solution, selected from an archive, where Gaussian distribution is used for parameter diversification. In the proposed approach, the Levy probability distributions are properly introduced in the solution construction step, in order to couple the ACOR algorithm with the exploration properties of the Levy distribution. The proposed approach has been tested on mathematical test functions…

A portable instrument for the location and identification of defects generating PD

A portable instrument based on an antenna probe and suitable for partial discharge detection, have been characterized through both laboratory and on-site experiments carried out on coils and stator windings of ac rotating machines. The antenna probe allows the capture of electromagnetic waves in a bandwidth of 0.1–100 MHz. Pulse signals and ac supply voltage reference are obtained by means of high-pass and low-pass filters, respectively, so avoiding the need of a direct connection with the objects under test. By this way, real-time phase resolved partial discharge patterns can be derived. Results of a comparison of the diagnostic information provided by PD patterns due to conducted and irra…

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

Spettrometria dielettrica di materiali isolanti nanocompositi a base di polimero-silicato lamellare

Reconfiguration Techniques of Partial Shaded PV Systems for the Maximization of Electrical Energy Production

In this paper, the research of the optimal layout of photovoltaic (PV) modules in a PV array giving the maximum output power under different shaded working conditions is carried out. The particular condition of non uniform solar exposition of the modules is analyzed. The study of the different configurations has been carried out starting from a circuital model used for the design of PV cells and for the simulation of the working behavior of PV arrays. The attained results appear to be interesting although the complexity of the problem in mathematical terms is huge when the number of panels is high. Moreover, the results confirm that this approach often allows to attain a higher electrical e…

ALGORITMI DI OTTIMIZZAZIONE DELLE CONNESSIONI DI SISTEMI FOTOVOLTAICI

Partial Discharge defects Classification by Discrete Wavelet Transform

Remote voltage synchronization for wireless Partial Discharge diagnostics

The main objective of this paper is the assessment of the exact phase angle displacement of each Partial Discharge, PD, pulse with respect to the voltage reference waveform. Such problem also referred to as ‘synchronization’ is relevant when the cable is not accessible and the PD measure is carried out in wireless mode. It is well known, that the angle phase shift, due to the propagation phenomenon on the transmission line, can be calculated knowing the line type and length and typical operating conditions of the transmission line. The setup comprises a customized electronic device, the “Phase check”, a server to collect remote measurements and a Look up table to provide corrections to the …

Energy Storage by using HVDC Power Cables

The development of HVDC (high voltage direct current) systems closely follow the growth of global energy requirements. In particular, HVDC cables are conveniently used for the interconnection of geographical areas which need a low environmental impact and/or when submarines interconnections have to be built up. The paper investigates the stored energy value in an HVDC cable during its normal duty and if it is possible to take advantage of this energy when the cable is disconnected for some reason. In particular, the idea is to store the cable energy, which would be dissipated uselessly, by using a dedicated system and then reuse it when favorable conditions hold, e.g a convenient economic s…

A new technique for partial discharges measurement under DC periodic stress

The aim of the present work is to recognize the type of defect in insulating materials employed in DC electrical systems. This analysis, under AC stress, is carried out by using the Phase Resolved method (PRPD). While, under constant voltage stress this method cannot be performed and measurements show complexities. In order to overcome these problems, a new technique is proposed, based on the application of a periodic continuous waveform. Simulation results, carried out by using a model based on a time-variable conductance of an air void defect, showed the PRPD pattern that can be obtain. Furthermore, compared to the constant DC stress, the measurement duration became lower and the discharg…

The Partial Discharge Behavior of Different Materials under DC Periodic Stress

The aim of the present work is to evaluate the PDs behavior by stressing a specimen with a new type of waveform named DCP. This waveform was proposed by the authors in a previous work with the aim to overcome the main issues of PDs under DC stress. In the previous work PDs test on Kapton specimen was performed. In this paper, we propose a new DCP test on a different insulating material, such as the XLPE. The obtained patterns and the acquired data have been evaluated in order to validate the DCP approach as a new method for PDs measure under constant stress. The behavior of the XLPE material has been reported and compared with the former measures obtained for Kapton material.

Predictability of PD inception in defects included in HVDC cables by conductivity models calibrated through experiments

To date, there are several methods for calculating the electric field distribution within a dielectric layer subjected to HVDC voltage. However, experimental techniques for evaluating the accuracy of models for calculating the electric field, such as space charge measurement, are often not precise enough to be used for this purpose. At the same time, the knowledge of Partial Discharge (PD) phenomenon occurring under HVDC stress is also not as developed as that of PD under HVAC voltage. The main goal of this research is to study the effectiveness of dielectric conductivity models to forecast the inception condition for PD under load and HVDC voltage stress. This study has been carried out by…

Studio di applicabilità e di fattibilità di tecniche diagnostiche CND basate su prove elettriche

Simplified Hybrid PD Model in Voids

In this paper a novel approach to model partial discharges (PD) activity taking place inside a spherical void in epoxy resin system has been traced. The approach is based on a time varying conductance of the inner void, subjected to multistress conditions: voltage, temperature and pressure. A simple lumped circuit macro-model simulates the global effects of PD activity: the different parameters influencing the discharge phenomenon in the void are taking into account by using a physical approach resulting in a time varying conductance inside the circuit. The evaluated PD activity has been compared with experimental and simulated one for the accessible and inaccessible part of the system. A d…

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

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. …

Detection of Radiated EM Transients by Exploiting Compact Spherical Antenna Features

In this paper, the features of a compact spherical antenna, already efficiently used for ultra wide band applications, are investigated by exploiting the possibility of detecting electromagnetic transients with frequency content up to the very high frequency range. Transient phenomena with the above mentioned frequency content are those encountered, for example, in partial discharge detection. The behaviour of the adopted compact spherical antenna enables to successfully detect the waveform of typical partial discharge transient radiated electromagnetic field, so preserving the information necessary for the subsequent pattern analysis, typically carried out by using classical conducted meas…

A Model for the Study of Sheath Currents in Medium Voltage Cables for Industrial Application

In this paper, the implementation of a simulation model for studying the effect of cross-bonding of metallic sheaths and/or non-magnetic armor of single-core medium voltage cables in the same circuit is discussed. With the use of single-core cables, the resistive losses due to the induced circulating currents in cable sheaths or armors causes an increase of cable temperature that reduces its ampacity. In addition, the risk of electric shock due to induced voltages may be present if a person is exposed to the armor/sheath at the unbounded end. For this reason, special bonding techniques are used to significantly reduce these currents. The authors have implemented a model that could be used t…

UN NUOVO APPROCCIO ALLA MODELIZZAZIONE DEGLI EFFETTI DELLE SCARICHE PARZIALI ATTRAVERSO LA MISURA DEL CAMPO ELETTROMAGNETICO

An improved MSD-based method for PD pattern recognition

In this paper a new method for multi source partial discharge (PD) pattern recognition by discrete wavelet transform, is presented. The proposed method is based on the application of multi-resolution signal decomposition (MSD) technique applied to a 3D PD pattern image. The multi-resolution technique has shown that some detail images (horizontal, vertical and diagonal) at different decomposition levels have frequencial characteristics typical of a single discharge phenomenon. By applying this method to a double-source PD pattern it is observed that one source prevails on the other. Taking advantage from the linearity of the biorthogonal wavelet functions by using a removal and reconstructio…

Overcoming synchronization issues in wireless technology Partial Discharge measurement

In this paper, several aspects of the fundamentals of wireless Partial Discharge (PD) measurements are first discussed. Then, the relevance of the problem of voltage synchronization in PD wireless diagnosis is outlined. When portable instruments are used for PD detection, the main issue is the voltage measurement at the site where the PD detection is carried out. When such analysis is carried out over shielded cables, the AC (50/60 Hz) voltage reference signal is not easily detectable, while one of the basic parameters for PD diagnosis, the displacement of the inception voltage of the PD as compared to the reference voltage, is not available. Even if highperformance sensors are readily avai…

A Two-End Traveling Wave Fault Location System for MV Cables

In this paper, a new low-cost device is proposed for fault location in power distribution system. The device is part of a system that should include several units installed in couples at the two ends of medium voltage (MV) cable lines. Their low cost justifies a widespread installation of these devices, moreover other functionalities could be considered so as to enrich the potential of the system for MV cables monitoring and asset management. The system exploits a two-end traveling wave technique, low complexity, and low-cost solutions both for the analog front end as well as for the communication infrastructure. A LoRa network is indeed considered as wireless modulation technique perfectly…

Pattern recognition di segnali di scariche parziali mediante l’applicazione della decomposizione wavelet multirisoluzione

A new approach to partial discharge detection under DC voltage

The continuing development of HVDC power transmission systems presents many problems related to evaluation of the reliability of power system assets [1]-[5]. In this context the identification of insulation defects plays a key role in preventing unexpected failures of electrical components. Partial discharge (PD) measurement is a useful approach to assessing the condition of HV power apparatus and cables. Such measurements are also widely employed for HVAC systems. The inception mechanisms of PD in AC systems are well-known, and measurements are usually performed following the IEC 60270 standard [6]. PD measurements under DC voltage present complexities related to the nature of the phenomen…

Space Charges and Partial Discharges Simultaneous Measurements under DC Stress

In the field of HVDC, the main causes of insulation aging are due to the space charge and PD phenomena. In particular, the purpose of the present work is to verify a possibility to measure simultaneously the space charge and the PDs under DC stress in order to evaluate the correlation between both phenomena. The space charge was measured by using a modified PEA cell and PDs were measured by using a novel wireless sensor system. The space charge profile and the PD pulses carried out simultaneously have been reported and discussed.

Partial discharge behavior under single phase half and full-bridge rectifier

The aim of the present work is to simulate partial discharges (PDs) phenomena under voltage stress close to the Direct Current (DC) waveform. The employed waveforms have been realized by using a full-wave and a half-wave rectifiers. After that, in order to generate a steadier voltage supply, a capacitive filter has been inserted in the output of the half-wave rectifier. Simulations have been carried out by modifying a previous software used in the case of Alternating Current (AC). Finally, experimental tests have been carried out in order to validate simulation results.

Space Charge Measurement under DC and DC Periodic Waveform

In High Voltage systems, Partial Discharges (PDs) monitoring are one of the main diagnostic instrument to evaluate the reliability of the apparatus. Under Alternating Current (AC) stress, PDs detection and recognition techniques are well consolidated. On the contrary, the monitoring of PDs under Direct Current (DC) stress is difficult due to complexities related to the nature of the phenomenon, which cause the beginning of PDs events in proximity of the dielectric breakdown. This problem has been partially overcome by using a continuous Periodic waveform (DCP) with positive average value, as described in a recent published work. Under DC stress, another degradation factor is the Space Charg…

Processo di denoising mediante wavelet di segnali dovuti alle scariche parziali

A Remuneration Model of Energy Community Members in Italy

The Directive (EU) 2018/2001 (RED II) requires Member States to authorize the constitution of consumers as self-consumers of renewable electricity by ensuring them non-discriminatory and disproportionate treatment. Member States must establish a favorable framework for promoting and facilitating the development of self-consumption, including in collective form (art. 21). According to the Directive, the granting of rights to renewable energy self-consumers who act collectively allows to increase the energy efficiency of households and helps to combat energy poverty by reducing consumption and supply tariffs. In Italy, the decree n. 162/2019 and then amended with Decree 199/2021 has partially…

A novel flexible approach for prediction and on line diagnostic of partial discharge

Partial discharges (PD), due to unavoidable local defects produced by the industrial manufacturing process, can determine local erosion of the material that may cause the electrical breakdown of the component in which the dielectric material represents the fundamental part. Recently, improved diagnostics of electrical insulation systems by means of electric PD measurements through a stochastic processing of the acquired data have been carried out. In this way, the identification of the defects as well, as the separation of multiple defects simultaneously active, have been performed. In this paper, a novel flexible approach for the on-line characterization of the defects in a dielectric mate…

A Comparison of Special Bonding Techniques for Transmission and Distribution Cables

In this paper, a review of the existing special bonding techniques for medium voltage (MV) and high-voltage (HV) cables is presented. Special bonding techniques have the purpose of reducing sheath currents, thereby limiting copper losses and the reduction of the ampacity of cables. The authors present a literature review to identify various bonding techniques and how these have evolved over the years thanks to new technologies. Simulations of the most used techniques have been performed in Matlab/Simulink, to compare their strengths and drawbacks.

Lévy Flights for Ant Colony Optimization in Continuous Domains

In this paper, the authors propose the use of the Levy probability distribution as leading mechanism for solutions differentiation in an efficient and bio-inspired optimization algorithm, ant colony optimization in continuous domains, ACOR. In the classical ACOR, new solutions are constructed starting from one solution, selected from an archive, where Gaussian distribution is used for parameter diversification. In the proposed approach, the Levy probability distributions are properly introduced in the solution construction step, in order to couple the ACOR algorithm with the exploration properties of the Levy distribution.

A digital device for the diagnosis of insulation systems

A complete innovative measurement system (D2SI - device for the diagnosis of insulation systems) for both acquisition, analysis and processing of partial discharge signals generated in insulation systems under voltage stress (IEC standard), was designed and realized; several measurements on practical insulation systems demonstrated the full and correct equipment operation.

Interpretation of PEA Output Signal in a Multilayer Specimen

The aim of the present work is to evaluate the acoustic waves behavior within the Pulsed Electro-Acoustic (PEA) cell, in case of a multilayer specimen, in order to avoid misinterpretation of the output signal. Due to the reflection phenomenon of the acoustic waves travelling within the PEA cell, the output signal could be distorted. Because this aspect, for a given PEA cell with certain ground electrode and absorber thicknesses, depends on the sound velocity and thickness of the specimen under test, the latter must be carefully sized. For this aim, some useful relationships, that must be taken into account are given and described. In particular, a three layers sample simulating an air void …

An improved MSD-based method for PD defects classification

The new proposed method of pattern recognition is based on the application of Multi-resolution Signal Decomposition (MSD) technique of wavelet transform. This technique has showed off interesting properties in capturing the embedded horizontal, vertical and diagonal variations within an image obtained from the PD pattern in a separable form. This feature was exploited to identify in the PD pattern's MSD, relative at various family of partial discharge sources, some detail images typical of a single discharge phenomenon. The classification of a generic PD phenomenon is feasible through a comparison between its detail images and the detail images typical of a single discharge phenomenon. Test…

Apparato di commutazione

La presente invenzione si riferisce ad un apparato di commutazione per il controllo e l'impostazione della configurazione circuitale dei pannelli di un modulo fotovoltaico.

A Dynamic Electrical Scheme for the optimal reconfiguration of PV modules under non-homogeneous solar irradiation

This paper presents a strategy for the maximization of the output power of photovoltaic (PV) systems under non homogeneous solar irradiation by means of automatic reconfiguration of the PV arrays layout. The innovation of the proposed approach is the employment of a simple Dynamic Electrical Scheme (DES), allowing a large number of possible modules interconnection, to be installed between the PV generator and the inverter. The models of the PV generator and of the DES have been realized and simulated with Simulink (Dynamic System Simulation for MATLAB). The attained experimental results appear to be quite interesting in terms of the attainable benefit in power and thus energy terms. The lim…

Sensore di campo elettromagnetico per la misura di scariche parziali

Test procedures for use of wireless partial discharges instrumentation in HV networks

On-field diagnostic methods based on Partial Discharge (PD) measurements for asset assessment in High Voltage (HV) sectors are experiencing a constant growth in recent years. This rise of interest motivated the research toward faster, reliable and less expensive methods and technologies to perform PD measurements. Recently, a portable instrument based on a wideband antenna sensor, intended for accurate partial discharge measurements, has been developed by the authors. This sensor allows to capture electromagnetic waves in a bandwidth ranging from 0.1-100 MHz as well as the electric field of the AC supply voltage to be used as a phase reference. This approach completely avoid the need of a d…

DWT-based method for partial discharge (PD) defects classification