Silvia Sangiovanni

Harmonics and PQ events monitoring in an electrified metro-transit system

The paper illustrates some results of a wide power quality (PQ) survey performed on the power supply installations of the metro-transit system serving the city of Rome, in Italy. The system currently includes two railway lines supplied at 1,500 V DC through several AC/DC 3.7 MW rated converters. The power supply of the system is provided at medium voltage (20 kV) from five different connections to the public grid. Fourteen electrical substations provide the total demand of about 20 MW of the system. The survey, currently still in progress, involves monitoring activities aimed at identifying possible PQ problems of various nature. Identification of typical daily patterns of harmonics distortion due to the system is even a task of the current survey.

Study and realization of an instrument FPGA based to implement curve-fitting algorithm (CFA)

An instrument based on FPGA technology able to determine in an only period and with a little number of samples the fundamental frequency of electrical net signal is been realized. The algorithm implemented on the instrument is a modified version of the well known Curve Fitting Algorithm (CFA) particularly suitable to determine Power Quality Parameters. A study of the uncertainty to evaluate the performances of the instruments is presented too.

A measurement campaign in a metro trains deposit/maintenance and repair site for PV production optimal sizing

The paper describes a measurement campaign conducted in a metro trains deposit/maintenance and repair site for the trains in operation on the metro line B of Rome. For the measurement campaign the network analyzer Chauvin Arnoux CA 8335 has been used. The measurements were conducted by performing a monitoring on general consumption and on relevant individual loads such as office building, lighting towers, lighting, lathe, etc. The knowledge of total energy consumption and of electrical loads allows the identification of possible different strategies for energy efficiency by using the PV production. Some evaluations are also conducted on the possible use of storage energy systems.

IVTs behavior in SF 6 switching transients: Fast front voltage impulse

Instrument Voltage Transformers (IVTs) introduce errors in power quality measure due to resonances effects at high frequency. The accuracy of IVTs, definite by standards, is only about nominal frequency and does not consider high frequency response. The paper reports the IVTs experimental analysis on resonances disturbances transferred to secondary side of Instrument Voltage Transformer. In particular the main results obtained from a laboratory survey on three currently marketed IVTs with same features but different manufacture are presented. IVTs are tested with very fast front voltage impulse whose waveform is similar to the characteristic one of SF6 switches operations.

Comparison among low-cost portable systems for thoracic impedance plethysmography

Impedance plethysmography is a technique which allows the monitoring of respiratory activity through the measurement of variations in the trans-thoracic impedance. Provided the measurement system has enough sensitivity, the same technique can also detect heartbeats, thus adding cardiac activity monitoring capabilities. In this paper, a comparison is performed between 2-electrode and 4-electrode systems, considering both volt-amperometric and AC-bridge solutions. Attention is focused on low-cost, easily portable, and reconfigurable measurement set-ups, whose performances are analyzed in terms of sensitivity and accuracy. To this end, LabVIEW virtual instruments based on a data acquisition card are employed. An experimental metrological assessment of the systems shows that their basic accuracy is definitely adequate for patient monitoring. However, based on a theoretical study on measurement resolution, only the volt-amperometric solution in 4-electrode configuration achieves enough sensitivity to correctly detect the cardiac activity. The above conclusion is verified by acquisitions made on several volunteers.

Perspectives of QoS Management Based on QoAS for 3G Communication Systems

The UMTS appear to be the communication system of the next future. In this system all the communication services will be included. This means that the Quality of Service (QoS) will have a great importance. So is envisaged that the management of the system will take in account the momentary system capabilities continually determined in real time. Until now, the quality of the links is determined by end-to-end in line procedures based on Bit Error Rate (BER) measurements. It is clear that an end-to-end procedure cannot detect the worse section of the link. To overcome this inconvenient the morerecent trend of QoS management is to realise a distributed monitoring of the whole system. Following this last trend this paper proposes a distributed off-line monitoring of the system based on the analysis of the Quality of Analog Signal (QoAS). This proposed analysis implies a high-speed analog to digital conversion of the Intermediate Frequency signal and a very complex processing. In this paper, the state-of-the-art researches performed in this perspective are described.