D. Di Cara

Frequency response of Measurement Current Transformers

In this paper the frequency response of two CTs is experimentally evaluated in the range of 30-600 Hz. A theoretical analysis of CTs behavior has been developed by means of the equivalent circuit. It was shown, by an experimental test, that, for the frequency range analyzed, the transformer equivalent circuit is a valid tool for the evaluation of CT performances.

Characterization of Current Transformers in the Presence of Harmonic Distortion

The CTs performance under distorted conditions are usually characterized by means of the frequency response test. In this paper a new way to characterize CTs, closer to real operative conditions, is proposed. The harmonic phase angle and ratio errors are measured when the CTs are excited with a nonsinusoidal current composed of a fundamental and one harmonic, with adjustable phase shift. The errors measured using the new approach were found larger than the ones obtained with the frequency response. This suggests that frequency response is not a reliable method to evaluate the CT performance under distorted conditions.

Experimental evaluation of an hybrid communication system architecture for smart grid applications

In this paper a new communication system architecture is proposed for the development of a SCADA system which can remotely monitor and control intelligent electronic devices (IEDs) connected to the low voltage distribution networks, i.e low voltage smart meter (SM), interface protection devises (IPS). New distributed metering systems and interface devices, together with a proper communication infrastructure (HiperLAN and narrowband power line communication (NB-PLC) on low voltage network), have been developed to allow monitoring the whole power system and controlling the distributed generators of a Smart Grid also in the presence of harmonic distortions. In this way, the electrical energy distribution operator (DSO) would be able to monitor the distribution network and to take decisions to maintain the stability and the power quality of the electrical system. Experimental tests have been carried out in the pilot smart grid of the island of Favignana.

A set of indicators for arc faults detection based on low frequency harmonic analysis

In this paper a novel set of indicators is presented for arc faults detection in electrical circuits. The indicators are defined starting from an experimental characterization of the arc fault phenomenon and the study of the arcing current in several test conditions, which were chosen in accordance with the UL 1699 Standard requirements. The proposed parameters are measured by means of a high resolution low frequency spectral analysis of the arcing current, which allows to achieve a good spectral resolution even with short observation windows.

High frequency modeling technique for three phase power electronics module

Nowadays, the high integrated power electronics modules (PMs), characterized by high speed, low loss and hard ware miniaturization, represent a new technology that meets the emerging demands of many applications, such us vehicle and home appliance, renewable energy sources in smart grid. The integration process and the high switching speeds increase the PM electromagnetic emissions that can create electromagnetic interference (EMI) with electric/electronic devices near the PMs. For this reason, electromagnetic compatibility (EMC) have to be carefully considered, yet in the design phase, to guarantee the reliability of PM systems. In this paper a method to develop a high frequency (HF) model, useful to study EMI phenomena of a three-phase PM, is presented. The method is based on experimental measurements at the PM external pins and it allows to extract internal inductive and capacitive parasitic coupling with out the knowledge of structural and physics parameters of the device. The PM HF model, developed in the 150kHz-30MHz frequency range, has been implemented in MATLAB® environment. The method has been experimental validated comparing the frequency responses of the PM characteristics with that obtained by the model.

Electric and magnetic emission in near field region and thermal behaviour of power module for photovoltaic application

The new power module, characterized by high power density, miniaturization of packages and layout and high frequency switching, are increasingly used in the field of in automotive, aircraft industry and for Distributed Generation (DG) connected to smart grid. To guarantee the reliability and safety of these systems, the electromagnetic compatibility (EMC) and thermal behavior, have to be carefully considered for these appliances. This paper describes a measurement methodology to characterize the electromagnetic emissions in near field zone produced by a PM prototype and its thermal behavior. In particular, the electric and magnetic fields, in the near field region in the frequency range 9kHz-3GHz is evaluated and an analysis of the temperature values achieved by the module during its operation in different load conditions is presented. The proposed methodology involve the evaluation of the PM electromagnetic and thermal emissions in standalone configuration, i.e. without its control and supply boards, because the aim is to characterize behavior of only the PM and to identify the EMI source and thermal hot-spots inside the power section.

Measurements methodology for the reliability evaluation of intelligent power modules

The paper describes a measurement methodology for the reliability evaluation of new intelligent power electronics modules (IPMs). In particular, the evaluation of the IPMs immunity to radio frequency conducted disturbances has been performed, at different operating thermal conditions, designing a suitable measurement set up in a shielded room. Moreover, the thermal performances of the devices have been analyzed, setting up a proper experimental test bench. The measurements procedures are detailed described.