Edoardo Fiorucci

Digital measurement station for power quality analysis in distributed environments

Today there is a wide application of different electronic apparatus that both produce electromagnetic disturbances on the supply power system and are sensitive to them. Power disturbances present on typical electric utility distribution systems degrade product quality, increase process downtime, and dissatisfy commercial customers. For these reasons, the monitoring of the quality of the supply networks has become an issue of international interest. To monitor power quality, in this paper, we propose a digital measurement station. Its main features are remote data transmission capability and reduced cost. It is a PC-based virtual instrument that offers the flexibility due to the high-level programming language, the familiar working environment of Windows, and the low cost of a widely used computer. The local area network or a modem card allows the measurement system to be controlled via a transmission control protocol/Internet protocol network, implementing in this way a distributed power quality evaluation system.

Survey on Voltage Dip Measurements in Standard Framework

This paper reports the results of the analyses on the accuracy of algorithms commonly adopted in instruments devoted to the detection and characterization of voltage dips (also called sags). This analysis is particularly interesting because the results of dip measurements are used for calculation of severity levels and site indexes that are important parameters in the assessment of quality level of power supply but also for selecting equipment with proper intrinsic immunity. Anyway, instruments for dip measurement still have unresolved technical and theoretical issues related to the characterization of their metrological performance, so it can be found that different instruments are significantly in disagreement in some actual measurements. This paper moves a step into the direction of deepening the knowledge about the measurement of voltage dips, pointing out the limits because of the adoption of the detection algorithms adopted in agreement with standard. It starts with a discussion about parameters that characterize voltage dips. Then, the analytical calculations of systematic deviations in the event characterization, introduced by the most diffused dip detection algorithms, in simplified measurement situations, are presented, underlining their remarkable impact with particular attention to short-dip event. The obtained relations are experimentally verified on a commercial power quality instrument. Brief remarks about the analysis of the main algorithms, alternative to that of the standard, for voltage dip detection are also reported.

Low cost smart power metering

Modern trends, including increased electricity requirements and improvements in grid management technologies, are causing the electric industry and regulators to review how the grid is achieved. With this aim, in this paper a low cost solution for the real-time energy management in a smart grid, is presented. It provides several smart meters, which act as slaves, that continuously monitor connected loads communicating with a data aggregator via CAN bus. Through the implemented web server the users can remotely control their consumption using a web browser. To prevent external attacks, a low computational cost protection software, based on Message Authentication Code (MAC), has been implemented. The paper illustrates the hardware architecture, discusses the adopted software solutions, and is completed with an example of energy monitoring for a generic household thanks the web server.

Embedded Power and Energy Measurement System Based on an Analog Multiplier

This paper deals with the development of an analog electronic wattmeter based on a high-accuracy electronic four-quadrant multiplier and appropriate amplifying and averaging circuits. The proposed instrument presents a simple design and is constructed using commercially available components. Its main advantage is that it can be integrated with the signal conditioning circuit, obtaining low cost, high resolution, and reduced dimensions. It can measure in circuits with very low power factors and nonsinusoidal waveforms. The implemented prototype is a portable laboratory instrument, integrated with a digital system capable of processing the signals, and displaying the main parameters of both electric power and energy. It has been designed to easily integrate the main blocks in that either industrial or civil equipment requiring the power measurement for monitoring or control purposes. A Fluke 6100A power standard is used to calibrate the wattmeter over a wide range of current magnitudes and widths and at power factors down to 0.02; several results are reported and discussed.

A Peer-to-Peer Distributed System for Multipoint Measurement Techniques

One of the main disadvantages of monitoring systems based on smart Web sensors is the difficulty to have a complete access to all data. In fact, nearly everyone of the actual available systems use proprietary embedded software to perform measurements, because only the manufacturer knows the internal hardware architecture and as servers exchange information. Moreover, those systems are not able to share information in a free way, because of using different implementations and protocols. The main goal of this paper is to present an implementation of a distributed measurement system, based on the web service approach. The proposed system is based on a freeware widely utilized technology, the Gnutella network, to route and share information adopting a low-cost hardware architecture. Gnutella, like most other peer-to-peer (P2P) applications, builds a virtual network with its own routing mechanisms at the application level. The implemented topology of this overlay network and the routing mechanisms have a significant influence on the application properties such as performance, reliability and scalability. The Gnutella architecture gives the possibility to create a monitoring network in which the clients are all connected without any user operation. In this paper, the authors describe the implemented Gnutella-based distributed measurement system and the architecture of the implemented prototype of low-cost smart web sensor.

A low-cost ultrasonic wind speed and direction measurement system

The paper deals with a low-cost transducer that implements an improved technique for wind speed measurement in open air. The instrument is a 2-axis ultrasonic anemometer, capable of monitoring both wind speed and direction. Its main advantage is that using the ultrasonic technique it has no moving parts, allowing for the utilization in a variety of applications requiring low maintenance and fast response to rapid wind gusts. Wind speed measurement for power turbine control can be considered as a reference application of it. The proposed instrument presents a simple design and is constructed using commercially available components, to reduce development costs. In the paper the proposed architecture is presented, discussing the algorithm applied to process the transduced ultrasonic signals. Some results obtained during the first tests are also presented and discussed, suggesting for successive improvements.

Uncertainty Issues in Direct and Indirect Efficiency Determination for Three-Phase Induction Motors: Remarks About the IEC 60034-2-1 Standard

Electric motors and the systems they drive are the single largest electrical end-use; it is estimated that they consume between 43% and 46% of all global electricity consumption. Recent studies show that efficiency values of induction motors can be successfully increased, with improvements up to 20%-30%. In 2009, the European Commission published a new regulation (640/2009) concerning requirements for the eco-compatible design of electric motors. In such a scenario, the experimental determination of induction motor efficiency is getting more and more important, because of the need of placing these motors in the right energy efficiency levels defined by international regulations. The correct motor classification strictly depends on the uncertainty associated with the efficiency determination. According to the IEC 60034-2-1 standard, the efficiency of three-phase induction motors can be determined by applying the direct or indirect efficiency technique. The direct procedure is suggested for low uncertainty efficiency measurements of single-phase induction motors and three-phase motors with rated power ≤1 kW. In this paper, we propose a comparative analysis between direct and indirect efficiency determination for three-phase induction motors, according to the IEC 60034-2-1 standard. The contribution of this paper consists in the comparison between the uncertainty calculations in indirect and direct efficiency determination for induction motors, to investigate the advisability of adopting the direct efficiency determination as reference method, because it is easier to implement and it has a good accuracy. This task is carried out starting from the accuracy requirements for measurement equipment, as demanded by the Guide to the Expression of Uncertainty in Measurement GUM. Some experimental results obtained with the indirect and direct efficiency determinations on a 3-kW three-phase two-pole induction motor are presented and discussed. A final suggestion related to a future version of IEC 60034-2-1 is also reported.

Measuring System for Microelectric Power

In this paper, we are mostly concerned with the measurement of electric micropower and energy. This parameter is essential to evaluate the energy efficiency of low power devices, such as wireless operated monitoring and control systems. It is also important to measure the standby power consumed by appliances and equipment while switched off. The measurement of power generated by the harvesting systems is another field of application. Thus, it is important to implement the power meters to accurately measure power . The common commercially available wattmeters are inaccurate for these low-power measurements for two main reasons: a limitation on the instrument dynamic range and the intermittent operating mode of some devices. Particularly critical is the current measurement, for the high gains required in most applications. In this paper, a measuring system for microelectric power and energy is proposed. It operates for voltage up to 3 Vpp and current from 1 pA to 5 mA, corresponding to an electric power down to around a fraction of microwatt. In the following, the system architecture is described, also discussing some experimental results obtained during the characterization test.

Evaluation of autonomic nervous system in sleep apnea patients using pupillometry under occlusal stress: a pilot study

Abstract Aims: Recently, it has been proposed that obstructive sleep apnea syndrome (OSAS) is characterized by an imbalance in autonomic nervous tone. Pupil size has been considered a valid test for studying the autonomic nervous system (ANS). Pupillometry is a simple and non-invasive tool to assess the size and dynamics of the pupil. The purpose of this study was to evaluate, by pupillometry, the hypothesis that subjects with OSAS present ANS dysregulation. Methods: The study group included 10 males aged between 40 and 50 years with polysomnographic diagnoses of mild OSAS. The control group included 10 males with similar ages with an apnea–hypopnea index (AHI) of less than 5, after polysomnography. Pupillometry was performed by digital infrared pupillometer (25 frame/s). Recordings were processed to measure the area of the pupil frame by frame. The subjects underwent four subsequent recordings: infrared light at rest mandible position (RP); infrared light at forced habitual occlusion (FHO); yellow-green light at RP; and yellow-green light at FHO. According to literature, linear and non-linear information was extracted from the recordings. Results: As expected, the two groups did not differ statistically in age and body mass index (BMI), while there was a significant difference in the AHI. In the within-group comparison of pupil size, there were significant differences between RP and FHO under infrared conditions in the control group. There was a significant difference in the determinism percentage (Det%) in the RP infrared condition between the control and OSAS groups. Conclusions: The results of the current study confirm ANS dysregulation in OSAS patients and provide a new possible strategy for studying this pathology by using pupillometry through linear and non-linear mathematical models.

An automatic test system for the dynamic characterization of PEM fuel cells

The adoption of fuel cells for industrial applications, transportations and home power generation has widely increased in recent years. For both the monitoring and characterization of those systems, the implementation of a suitable test system is needed. In a fuel cell both chemical and electric sections can be founded, so to control its behavior the measurement of different parameters, as current, voltage, flow rate of the reactants and cell temperature is required. The performance evaluation of a fuel cell requires both static and dynamic characterization, especially for the automotive applications, in which there is a dynamic variation of electric load. In this paper we are mostly concerned with the implementation of an automatic test system for both static and dynamic characterization of PEM fuel cells. A complete testing procedure is proposed and the experimental results are shown.