1,721,106 research outputs found
Improved Fine Particles Monitoring in Smart Cities by Means of Advanced Data Concentrator
Full text linkTraffic reduction and air-quality improvement are among the main goals of several projects worldwide. This article presents a fine particle monitoring based on heterogeneous air quality mobile sensors and an advanced data concentrator (AdDC), so that the level of pollution in the urban area, where few accurate fixed measurement stations are present, can be assessed with better accuracy. Some urban buses are used to carry low-cost sensors, thus implementing a mobile sensor network and increasing the time and space resolution of air quality information. The data obtained by these low-cost sensors are significantly affected by uncertainties, also due to atmospheric factors, such as humidity. The proposed AdDC processes all the obtained measurements and exploits the information obtained by the accurate fixed stations to improve the accuracy of the low-cost mobile sensors. In particular, a new compensation methodology, specifically targeted to the fine particles monitoring, is proposed. The monitoring of relative humidity is added, with the relevant on-the-fly calibration, so that the measured values can be used to correct the effects of humidity on PM2.5 sensors. The validity of the proposed system is proven by means of simulations performed on an appropriate set up
A PMU-based Technique for the Simultaneous Estimation of Systematic Measurement Errors, Line Parameters and Tap Changer Ratio
No full textAccurate monitoring tools are fundamental for the proper operation of the transmission grids. In this context, an essential requirement for the transmission system operator is the availability of accurate knowledge on transmission line and transformer characteristics. Despite the high accuracy of the increasingly used Phasor Measurements Units (PMUs), there are still significant issues associated with the knowledge of the actual line parameters and on the actual tap changer ratio. In this regard, the paper proposes a method to estimate simultaneously the line parameters, the tap changer ratio, and the systematic measurement errors associated with the instrument transformers. With an appropriate model of the measurement chain, which includes the uncertainties associated with instrument transformers and PMUs, a linear formulation of the line and transformer constraint equations can be applied and accurate results can be obtained. The validity of the proposed method is confirmed by different types of tests performed on the IEEE 14-bus test system
Software defined networking applied to the heterogeneous infrastructure of Smart Grid
No full textThe increased need for power quality monitoring and active control of distribution grid necessitates the introduction of the Smart Grid (SG) approach, requiring an efficient ICT system for the monitoring and control of distribution grid state. The main obstacle to deployment of SG in real system is the lack of an efficient communication infrastructure. The use a heterogeneous network, which employs various technologies, appears to be the most promising solution. Nevertheless, the management of these communication systems has proven to be hard and error prone. In this paper, a Software Defined Networking (SDN) approach has been proposed to manage SG communication system applied to grid monitoring/supervision. The preliminary feasibility analysis is promising, although a more detailed modeling and analysis of the system is needed due to the extreme heterogeneity of the network
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Power Quality Meters Based on Digital Inputs: A Feasibility Study
No full textModern power systems are experiencing a rapid transition towards a fully digital monitoring and control paradigm. In compliance with the specifications of the IEC 61850 standards family, measurement data shall be output by non-conventional instrument transformers according to the Sampled Value (SV) communication protocol. It is thus reasonable to expect that also Power Quality (PQ) measurements shall rely on SV data streams. Furthermore, due to the limited sampling frequency values considered in the standard, it is essential to evaluate the impact of different samples per cycle or packet loss conditions while detecting a PQ event. This paper investigates the feasibility of a PQ meter specific for voltage dips detection based only on SVs. To this end, a prototype hardware and software architecture is presented and characterized in standard and real-world test conditions. An experimental validation against a commercial device confirms the potential of the proposed SV-based PQ meter and the performance dependence on SV data stream integrity
Accurate measurement system for power quality monitoring in a real grid context
No full textThis paper presents a complete measurement system for accurate and synchronized power quality monitoring in a real distribution grid context. The system has been designed to monitor both medium voltage and low voltage levels in industrial sites in the region of Sardinia, Italy. It is composed of two complete measurement chains including suitable transducers, permitting the monitoring of the quality of the power supply to be obtained, and synchronization capabilities. The system was designed to meet the needs of real industrial plants where distributed generators are installed as is now common in modern distribution grids. The validity of the system has been verified on the field in an industrial site close to the city of Cagliari, Italy
Caratterizzazione di selezioni di leccio (Quercus ilex L.) provenienti da popolazioni della Sardegna Centrale
No full textPMU-based estimation of systematic measurement errors, line parameters and tap changer ratios in three-phase power systems
Full text linkThe availability of accurate data is fundamental for several monitoring and control applications of modern power grids. Nevertheless, the knowledge of critical data such as transmission line and transformer parameters is often affected by uncertainty. This can lead to important problems in the correct management of the power systems. In spite of a monitoring infrastructure that is being renewed thanks to new generation devices providing synchronized measurements, the actual values of line parameters and tap changer ratios are still affected by uncertainty sources that need to be properly considered. The behaviour of all the elements involved in the measurement chain must be duly modelled. This paper proposes an improved method to carry out the simultaneous estimation of line parameters, tap changer ratios, and systematic measurement errors for a three-phase power system. The proposed method is based on the suitable modelling of the measurement chain and on three-phase constraint equations (voltage drop and current balance) of all the components involved. Its effectiveness is confirmed by tests performed on a IEEE 14 bus test system reproduced as a three-phase system under different operative conditions
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