Dario Petri
University of Trento, Industrial Engineering, Faculty Member
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This chapter analyzes one of the most common instruments in use in laboratories or fieldwork. It presents some history showing the characteristics of analog and digital oscilloscopes and how they have evolved through decades. The chapter... more
This chapter analyzes one of the most common instruments in use in laboratories or fieldwork. It presents some history showing the characteristics of analog and digital oscilloscopes and how they have evolved through decades. The chapter also presents a brief description of the different waveforms one may find in normal engineering work. It describes different waveform characteristics and how to measure them using oscilloscopes. By describing their building blocks it is easy to understand limitations of each type of oscilloscope. The chapter gives a general idea of how to use oscilloscopes by explaining each of the most common controls found in their front panels. It shows the performance characteristics of oscilloscopes and how they can affect the measurements performed with them. The chapter outlines different types of probes available and their characteristics to be able to use the correct one for each different application.
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Abstract A Renewable Energy Community (REC) is a legal entity aggregating different users sharing their own resources to reduce both electricity bills and CO 2 emissions. This paper presents and analyses the impact of a bi-objective... more
Abstract A Renewable Energy Community (REC) is a legal entity aggregating different users sharing their own resources to reduce both electricity bills and CO 2 emissions. This paper presents and analyses the impact of a bi-objective strategy to optimise the capacity of the Battery Energy Storage Systems (BESSs) of REC prosumers equipped with photovoltaic (PV) generators. The optimisation problem is solved through a custom implementation of the Non-dominated Sorting Genetic Algorithm-II (NSGA-II) and has two contrasting objectives: maximising the self-sufficiency of the REC from the main grid, while minimising the BESS capacity of all REC members. A key novelty of this study is the prosumer-driven perspective, which allows to exclude the REC members who do not want to install a BESS through a linear optimisation constraint. Moreover, the proposed approach ensures that probabilities of over- or under-voltages are compliant with the limits specified by Distribution System Operators (DSOs). Such probabilities, as well as the line and BESS losses, are estimated within the optimisation loop through grid-level simulations performed in OpenDSS. Both a standard peer-to-grid (P2G) and a more REC-oriented peer-to-peer (P2P) energy sharing policy are analysed and their performance is assessed in different seasons and considering both the current energy demand and a possible future scenario, in which electrical heat pumps are widely used. The results of a case study based on a modified version of the IEEE 906-bus European Low Voltage distribution grid show that a if the total BESS capacity assigned to all REC prosumers exceeds a given threshold value, the benefits for the REC become minor. Assuming to choose the optimal BESS capacity solutions corresponding to the threshold value in the summer season (i.e., when PV and BESSs are most exploited), the overall energy losses are reduced roughly by 20%–40% for both P2G and P2P battery controls. The CO 2 emissions instead, are reduced by 10% to 50% with the P2P policy having a slight edge over the P2G one. The P2P energy sharing policy spreads the economic benefits of energy savings more evenly among REC members, and the return on investment is generally higher if the electricity demand increases.
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ABSTRACT Next-generation phasor measurement units (PMUs) are expected to play a key role for monitoring the behavior of future smart grids. While most of the PMUs used nowadays in transmission networks rely on static phasor models, more... more
ABSTRACT Next-generation phasor measurement units (PMUs) are expected to play a key role for monitoring the behavior of future smart grids. While most of the PMUs used nowadays in transmission networks rely on static phasor models, more sophisticated representations and stricter accuracy requirements are needed to track amplitude, phase, and frequency changes of power waveforms in strongly dynamic scenarios as those expected in future distribution systems. In this paper, a discrete Fourier transform (DFT)-based algorithm based on a dynamic phasor model (referred to as interpolated dynamic DFT-based synchrophasor estimator) is used to estimate not only amplitude and phase of the collected waveforms, but also their frequency and rate of change of frequency. The performances of the proposed method are evaluated through multiple simulations in different steady-state and transient conditions described in the Standard IEEE C37.118.1-2011.
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Fine-grained state estimation is expected to play a key role in smart grid monitoring and control. The most common class of state estimators at both transmission and distribution level relies on the so-called Weighted Least Squares (WLS)... more
Fine-grained state estimation is expected to play a key role in smart grid monitoring and control. The most common class of state estimators at both transmission and distribution level relies on the so-called Weighted Least Squares (WLS) approach. While various, well-established implementations of WLS-based state estimators exist, all solutions typically exploit redundant data to assure full state observability and to build well conditioned matrices. At the moment, in the specific case of distribution networks just a few “true” measurement points are usually available. Therefore, the current distribution system state estimation (DSSE) techniques heavily rely on “pseudo” measurements based on historical load data. However, in future the traditional distinction between transmission and distribution systems is expected to blur and a larger number of heterogeneous instruments (e.g. the PMUs) could be deployed for real-time smart grid monitoring. In this respect, the purpose of this paper is twofold, i.e. i) to analyze in general how the uncertainty of different types of measurements may affect WLS-based state estimation accuracy when a minimum number of measurements is considered and ii) to identify a criterion for minimizing the sensitivity to measurement uncertainty. In the paper, the results of the theoretical analysis are validated through simulations in a case study.
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In this paper, we discuss nonparametric estimation of the probability density function (PDF) of a univariate random variable. This problem has been the subject of a vast amount of scientific literature in many domains, while statisticians... more
In this paper, we discuss nonparametric estimation of the probability density function (PDF) of a univariate random variable. This problem has been the subject of a vast amount of scientific literature in many domains, while statisticians are mainly interested in the analysis of the properties of proposed estimators, and engineers treat the histogram as a ready-to-use tool for a data set analysis. By considering histogram data as a numerical sequence, a simple approach for PDF estimation is presented in this paper. It is based on basic notions related to the reconstruction of a continuous-time signal from a sequence of samples. When estimating continuous PDFs, it is shown that the proposed approach is as accurate as kernel-based estimators, widely adopted in the statistical literature. Conversely, it can provide better accuracy when the PDF to be estimated exhibits a discontinuous behavior. The main statistical properties of the proposed estimators are derived and then verified by simulations related to the common cases of normal and uniform density functions. The obtained results are also used to derive optimal, i.e., minimum integral of the mean square error, estimators.
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In this paper we present a novel technique based on a learning-from-examples approach for dynamic compensation of sensors. The context of application is the area of Wireless Sensor Networks, where simple but at the same time efficient... more
In this paper we present a novel technique based on a learning-from-examples approach for dynamic compensation of sensors. The context of application is the area of Wireless Sensor Networks, where simple but at the same time efficient signal processing methods have to be implemented on local 8-bits microcontrollers.
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Excessive or improper street lighting is currently responsible for a significant waste of electrical energy in many cities worldwide. In order to improve energy efficiency, the traditional light posts are expected to be gradually replaced... more
Excessive or improper street lighting is currently responsible for a significant waste of electrical energy in many cities worldwide. In order to improve energy efficiency, the traditional light posts are expected to be gradually replaced by smart systems able to adapt the features of the emitted light to different environmental, traffic, or crowdedness conditions. Power Line Communication (PLC) is the natural choice to support smart light control, since no additional communication infrastructure is needed. However, at the moment not so many simulation tools exist to guide the design and the deployment of smart lighting systems based on PLC. In this paper, we partially address this issue by presenting suitable circuit models that can be used to analyze (through simulations at the physical layer) the behavior of narrowband PLC (NB-PLC) signals transmitted over low-voltage (LV) lines for street light control. The proposed approach is quite simple from the computational point of view, and it is scalable enough to evaluate the quality of PLC signals in large networks with different topologies. The results of several simulations, with signals in the frequency range 95-148.5 kHz, have been compared with the outcomes of some laboratory experiments over a test line.
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Research Interests: Engineering, Electronic Engineering, Computer Science, Embedded Systems, Microcontrollers, and 15 moreDigital Signal Processors, Software, System on Chip, Microcontroller, Low Power, Theoretical Analysis, Measurement Problem, System on a Chip, Digital Signal Processor, Operant Conditioning, Embedded System, Electrical And Electronic Engineering, Multimeter, Measurement Uncertainty, and DIGITAL MULTIMETER
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Abstract The paper illustrates the development of low cost multichannel digital instrumentation for real-time control applications. The realization is based on the use of an advanced digital signal processing chip, providing the necessary... more
Abstract The paper illustrates the development of low cost multichannel digital instrumentation for real-time control applications. The realization is based on the use of an advanced digital signal processing chip, providing the necessary computing power and processing throughput. Algorithms perform Discrete Fourier Transform spectral analysis of the incoming signals and further process data to compensate for the effects of spectral leakage. A variety of parameters can be obtained with good accuracy from the knowledge of signal spectra simply by adopting different computing routines. The application of a two channel instrument in the monitoring of electrical power under nonsinusoidal conditions is considered, and results are given for the case of linear loads. Absolute measurement errors are of the order of 10-4-10-5, while a sampling rate in excess of 200kHz per channel is achieved. The structure of the instrument is very simple, and only standard devices are needed to realize it. As a result, it is well suited as a low cost and flexible measurement block in control systems.
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Electrical waveform phasor measurements are receiving an increasing interest due to their key role in high-performance monitoring of future smart grids. In particular, different estimation algorithms based on a dynamic phasor model have... more
Electrical waveform phasor measurements are receiving an increasing interest due to their key role in high-performance monitoring of future smart grids. In particular, different estimation algorithms based on a dynamic phasor model have been recently proposed in order to comply with the strict requirements needed to accurately track amplitude, phase, and frequency changes of power waveforms in distribution systems. In this paper, a Kalman smoother based on a dynamic phasor model is proposed to estimate amplitude, phase, frequency and rate of change of frequency of the collected waveforms. The accuracy of the proposed approach is evaluated through simulations in different conditions described in the Standard IEEE C37.118.1-2011 and a comparison with a state-of-the-art method is performed.
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In this paper; the authors address the prob- lem of characterizing and analyzing power systems un- der non-sinusoidal conditions. A method is presented that allows the estimation of relevant parameters of the spectral components in which... more
In this paper; the authors address the prob- lem of characterizing and analyzing power systems un- der non-sinusoidal conditions. A method is presented that allows the estimation of relevant parameters of the spectral components in which the signals can be decomposed, via an FFT-based procedure. The results are compared with those provided by procedures pro- posed in the literature and information is given for al- lowing a straightforward application of the algorithm.
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Abstract The accuracy performance that an be achieved by post-processing the samples provided by a dithered quantizer is analysed in this paper for both stochastic and deterministic dithering. In the former case the quantization error... more
Abstract The accuracy performance that an be achieved by post-processing the samples provided by a dithered quantizer is analysed in this paper for both stochastic and deterministic dithering. In the former case the quantization error average and variance are considered and the number of effective bits of the system output is evaluated for uniformly and Gaussian distributed dither signals. Then the accuracy achieved by using a deterministic dithering is analysed and a new approach for optimizing the system performance is proposed. All the reported results have been validated by means of computer simulations.
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The paper presents a programming environment for robotics based on a threaded code architecture. The environment is supported by a multiprocessing operating system and in-cludes a programming language, an interactive interpreter, a... more
The paper presents a programming environment for robotics based on a threaded code architecture. The environment is supported by a multiprocessing operating system and in-cludes a programming language, an interactive interpreter, a debugger, and a multi-window manager. The paper illustrates how the threaded code organization on which the system is based has proved beneficial in obtaining a good integration of the programming tools.
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ABSTRACT This paper deals with a new design criterion aimed at keeping the decisional risks associated to conformance testing procedures below given target values. The proposed approach is based on two closed-form analytical expressions... more
ABSTRACT This paper deals with a new design criterion aimed at keeping the decisional risks associated to conformance testing procedures below given target values. The proposed approach is based on two closed-form analytical expressions describing the dependence of both the consumer's risk (CR) and the producer's risk (PR) on three essential parameters for conformance testing, i.e. the process capability index (CI), the test uncertainty ratio (TUR) and the gauging to tolerance interval ratio (GTR). Such approximate expressions are not only very accurate, but also much less computationally demanding than the implicit, integration-based expressions of CR and PR. This assures faster results and less numerical problems when the values of TUR and GTR meeting the wanted CR and PR requirements are determined.
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ABSTRACT In the near future, Phasor Meaurement Units (PMUs) are expected to play a key role not only in power transmission networks, but also to monitor power flows within distribution networks. Unfortunately, in order to face the... more
ABSTRACT In the near future, Phasor Meaurement Units (PMUs) are expected to play a key role not only in power transmission networks, but also to monitor power flows within distribution networks. Unfortunately, in order to face the challenges of next-generation smart grids, faster and more accurate techniques have to be developed for measuring waveform phasors, fundamental frequencies and rate of change of such frequencies (ROCOF). While the Standard IEEE C37.118.1-2011 defines clear accuracy and responsiveness boundaries for synchophasor estimation under the effect of different type of disturbances, the proposed limits have sometimes been considered as inadequate for distribution networks (either too strict or too loose). In this paper, after a brief overview of the general PMU architecture, the performance of two classes of phasor estimators (i.e. based on Discrete Fourier Transform and Least Squares optimization, respectively) are shortly, but effectively analyzed and compared both in steady-state and transient conditions.
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Currently, size of data is celebrated while only their usefulness in decision-making is actually important. Principles, methodologies and techniques of metrology are crucial to ensure proper and effective collection and use of data.... more
Currently, size of data is celebrated while only their usefulness in decision-making is actually important. Principles, methodologies and techniques of metrology are crucial to ensure proper and effective collection and use of data. Unfortunately, the fundamentals of metrology are seldom offered in educational degree programs, including those in scientific and technological subjects. Consequently, we should not be surprised if dataism (i.e., unconditioned belief in data) is spreading and a tsunami of improperly used data is submerging us. In the age in which measurements permeate all areas and every level of society with the expectation of promoting inconceivable socio-economic progress, underestimating the relevance of metrology is likely to lead to many serious potentially negative consequences.
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ABSTRACT The real-time, high-accuracy measurement of electrical waveform phasors is one of the many open challenges that need to be tackled in future smart grids. In this paper, the accuracy of three well-known synchrophasor estimators... more
ABSTRACT The real-time, high-accuracy measurement of electrical waveform phasors is one of the many open challenges that need to be tackled in future smart grids. In this paper, the accuracy of three well-known synchrophasor estimators based on the single-cycle Discrete Fourier Transform (DFT) is evaluated under the effect of static frequency offsets, amplitude modulation and phase modulation. Compared with other research works dealing with the same topic, in this paper phasor estimation accuracy is assessed exhaustively, by varying multiple model parameters at the same time in order to determine the maximum (and minimum) Total Error Vector (TVE) values. This approach leads to a fair performance comparison between the considered techniques.