Dr. Loredana Cristaldi

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Academic Career Length

33Years (1994-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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10 December 2002 in IEEE Transactions on Instrumentation and Measurement

Journal Article

A distributed system for electric power quality measurement

Loredana Cristaldi

Alessandro Ferrero

Simona Salicone

The problem of evaluating power-quality is becoming an impelling need due to the proliferation of disturbing loads in the electric power systems. Unfortunately, the identification of the sources disturbing the system cannot generally be achieved by means of measurements in a single metering section of the electric network. This paper proposes a distributed measuring system to monitor a number of power-quality indices on every load connected to the same point of common coupling, to transmit the measured values to a master device that processes them in order to locate the sources of unbalance and harmonic distortion and to quantify the effects of such disturbances on power quality. The results of some experimental work performed on a low-voltage network are also reported.

28 August 2013 in IEEE Transactions on Instrumentation and Measurement

Journal Article

An Improved Model-Based Maximum Power Point Tracker for Photovoltaic Panels

It is well known that in a photovoltaic (PV) plant, the modules are connected to switch-mode power converters to enhance the power output in every environmental condition. This task is performed by the maximum power point tracker (MPPT), which provides a current or voltage reference to the converter. Traditional perturb and observe or incremental conductance algorithms are not efficient in rapidly changing conditions, whereas a model-based (MB) MPPT offers a better dynamic performance. Because it is relatively easy to obtain an accurate model of a single PV panel, thus predicting the maximum power point voltage for given environmental conditions, MB MPPTs seemed to be attractive for employing in module integrated converters. Conventional MB MPPT algorithms, however, usually require an expensive pyranometer to properly operate. In this paper, starting from a new set of equations modeling a PV module, a novel MB MPPT technique, which does not require the direct measurement of the solar radiation, is proposed and experimentally validated.

1 June 1995 in IEEE Transactions on Instrumentation and Measurement

Journal Article

Harmonic power flow analysis for the measurement of the electric power quality

Loredana Cristaldi

Alessandro Ferrero

1 June 2012 in IEEE Transactions on Instrumentation and Measurement

Journal Article

A Simple Photovoltaic Panel Model: Characterization Procedure and Evaluation of the Role of Environmental Measurements

The growing number of installed photovoltaic (PV) plants is making the simulation of their behavior and their effects on the power network more and more relevant. In this context, an accurate yet simple model of the panels is beneficial for evaluating the power production as well as the system efficiency in off-line and on-line analysis. In the preliminary design stages of large plants, this kind of model can support design and decision making, allowing for the simulation of the entire plant and the testing of various power architectures. During the operation, such models may support monitoring, diagnostic, and control functions. In this paper, a model of PV panel, suitable for the aforementioned applications, is presented together with a simple procedure for the identification of its parameters. The critical issues related to the measurement and the estimation of the required environmental quantities are analyzed together with their main metrological requirements. Finally, the experimental validation of the proposed model and algorithms is presented using as a case study the estimation of the energy production of a domestic solar plant.

1 October 2001 in IEEE Transactions on Instrumentation and Measurement

Journal Article

A linearization method for commercial Hall-effect current transducers

The need for high-current transducers featuring wide-band and high-insulation levels is becoming a more and more impelling need in the electric power network, as the current distortion increases due to the proliferation of nonlinear, time-variant loads. The closed-loop Hall-effect current transducers show a good compromise between cost and metrological performance. On the other hand, they may introduce an unacceptable nonlinearity error when the dynamic range of the input current is a reduced portion of the dynamic range of the transducer and may show a large drift of their gain with temperature. The paper proposes a simple method for reduction of the nonlinearity error when the input signal is an unbiased sinewave and the automatic calibration of the gain. Experimental results are also reported, showing the method effectiveness.

24 May 2024 in Sensors

Journal Article

A Review of Degradation Models and Remaining Useful Life Prediction for Testing Design and Predictive Maintenance of Lithium-Ion Batteries

Nedka Dechkova Nikiforova

We present a novel decision-making framework for accelerated degradation tests and predictive maintenance that exploits prior knowledge and experimental data on the system’s state. As a framework for sequential decision making in these areas, dynamic programming and reinforcement learning are considered, along with data-driven degradation learning when necessary. Furthermore, we illustrate both stochastic and machine learning degradation models, which are integrated in the framework, using data-driven methods. These methods are presented as a valuable tool for designing life-testing experiments and for maintaining lithium-ion batteries.

About Me

Loredana Cristaldi (Senior Member, IEEE) received the M.Sc. degree in electrical engineering from the University of Catania, Catania, Italy, in 1992, and the Ph.D. degree in electrical engineering from the Politecnico di Milano, Milan, Italy, in 1996. From February 1997 to January 1999, she worked at Italtel in the Switching Business Unit Energy Systems section. From February 1999 to November 2005, she served as a researcher for the SSD ING-INF/07 at the Department of Electrical Engineering of Politecnico di Milano. From November 2005 to November 2022, she served as Associate Professor of Electrical and Electronic Measurements at Politecnico di Milano (DEIB Department, Dipartimento di Elettronica, Informazione e Bioingegneria). She is currently a Full Professor of electrical and electronic measurement in the same department. Her current research interests include the measurements of electric quantities under nonsinusoidal conditions, virtual instruments, and measurement methods for reliability, monitoring, and fault diagnosis. Prof. Cristaldi is a member of the PhD council in “Ingegneria Elettrica/Electric Engineering” of Politecnico di Milano. Prof. Cristaldi is a member of the TC 315 (WG6) and TC56 CEI. She is the chair of the TC06 (Emerging Technologies in Measurements) of IEEE Instrumentation and Measurement Society and is the Counselor of the IEEE Student Branch of the Politecnico di Milano.

Dr. Loredana Cristaldi

Dr. Loredana Cristaldi

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About Me